From patchwork Mon Jun 25 23:30:39 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bill Schmidt X-Patchwork-Id: 167266 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) by ozlabs.org (Postfix) with SMTP id 1DF41B6FB6 for ; Tue, 26 Jun 2012 09:32:48 +1000 (EST) Comment: DKIM? See http://www.dkim.org DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=gcc.gnu.org; s=default; x=1341271969; h=Comment: DomainKey-Signature:Received:Received:Received:Received:Received: Received:Received:Received:Received:Message-ID:Subject:From:To: Cc:Date:Content-Type:Content-Transfer-Encoding:Mime-Version: Mailing-List:Precedence:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:Sender:Delivered-To; bh=XdVmqQ7aU+IHPXz7WRoY oRTtBP0=; b=jxHm1kFpHCD7YrjRsjW8rT9e8JQ3qBF3CLCJrVYKUAJzGP1ueHjv shD5L81OC2zM7TKcrpOJjeyR20U+Cuq2k8aORlSmK6dlHwOPfC9sbJFDRDRIXQEY 5+uOQPpYExz2XWWwtZTiu8pdbVMHjye/7OTcM/zETIFHJNy5eU6Pp2Q= Comment: DomainKeys? See http://antispam.yahoo.com/domainkeys DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=default; d=gcc.gnu.org; h=Received:Received:X-SWARE-Spam-Status:X-Spam-Check-By:Received:Received:Received:Received:Received:Received:Received:Message-ID:Subject:From:To:Cc:Date:Content-Type:Content-Transfer-Encoding:Mime-Version:X-Content-Scanned:x-cbid:Mailing-List:Precedence:List-Id:List-Unsubscribe:List-Archive:List-Post:List-Help:Sender:Delivered-To; b=kKqndikcOJHt3yCqpCxUsOISyMAdT9FmnE8RBBAoscCfe8eEMatmUd8W+f7MO/ d4ePVuUxUeryMgtFVBMH0Tr6F5Ga45D8slVOKgpw7IVOxDS4P7t13inJovFxmbtH /eqFzqTwmWeGMojAmeCAuqRxR325k6aXWtf7AuHp9gLqg=; Received: (qmail 8701 invoked by alias); 25 Jun 2012 23:32:34 -0000 Received: (qmail 8093 invoked by uid 22791); 25 Jun 2012 23:32:21 -0000 X-SWARE-Spam-Status: No, hits=-5.2 required=5.0 tests=AWL, BAYES_50, KHOP_RCVD_UNTRUST, RCVD_IN_DNSWL_HI, RCVD_IN_HOSTKARMA_W, TW_CF, TW_TM, T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from e33.co.us.ibm.com (HELO e33.co.us.ibm.com) (32.97.110.151) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 25 Jun 2012 23:31:57 +0000 Received: from /spool/local by e33.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 25 Jun 2012 17:31:54 -0600 Received: from d03dlp03.boulder.ibm.com (9.17.202.179) by e33.co.us.ibm.com (192.168.1.133) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Mon, 25 Jun 2012 17:31:41 -0600 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 62F4019D804A for ; Mon, 25 Jun 2012 23:31:27 +0000 (WET) Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q5PNUwZP183914 for ; Mon, 25 Jun 2012 17:31:13 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q5PNUhWs021419 for ; Mon, 25 Jun 2012 17:30:43 -0600 Received: from [9.76.43.27] (sig-9-76-43-27.mts.ibm.com [9.76.43.27]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q5PNUeGf020541; Mon, 25 Jun 2012 17:30:41 -0600 Message-ID: <1340667039.2861.5.camel@gnopaine> Subject: [PATCH] Strength reduction From: "William J. Schmidt" To: gcc-patches@gcc.gnu.org Cc: rguenther@suse.de, bergner@vnet.ibm.com Date: Mon, 25 Jun 2012 18:30:39 -0500 Mime-Version: 1.0 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12062523-2398-0000-0000-000007E4AA56 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Delivered-To: mailing list gcc-patches@gcc.gnu.org Here's a new version of the main strength reduction patch, addressing previous comments. A couple of quick notes: * I opened PR53773 and PR53774 for the cases where commutative operations were encountered with a constant in rhs1. This version of the patch still has the gcc_asserts in place to catch those cases, but I'll plan to remove those once the patch is approved. * You previously asked: >> >> +static slsr_cand_t >> +base_cand_from_table (tree base_in) >> +{ >> + slsr_cand mapping_key; >> + >> + gimple def = SSA_NAME_DEF_STMT (base_in); >> + if (!def) >> + return (slsr_cand_t) NULL; >> + >> + mapping_key.cand_stmt = def; >> + return (slsr_cand_t) htab_find (stmt_cand_map, &mapping_key); >> >> isn't that reachable via the base-name -> chain mapping for base_in? I had to review this a bit, but the answer is no. If you look at one of the algebraic manipulations in create_mul_ssa_cand as an example, base_in corresponds to Y. base_cand_from_table is looking for a candidate that has Y for its LHS. The base-name -> chain mapping is used to find all candidates that have B as the base_name. * I added a detailed explanation of what's going on with legal_cast_p. Hopefully this will be easier to understand now. I've bootstrapped this on powerpc64-unknown-linux-gnu with three new regressions (for which I opened the two bug reports). Ok for trunk after removing the asserts? Thanks, Bill gcc: 2012-06-25 Bill Schmidt * tree-pass.h (pass_strength_reduction): New decl. * tree-ssa-loop-ivopts.c (initialize_costs): Make non-static. (finalize_costs): Likewise. * timevar.def (TV_TREE_SLSR): New timevar. * gimple-ssa-strength-reduction.c: New. * tree-flow.h (initialize_costs): New decl. (finalize_costs): Likewise. * Makefile.in (tree-ssa-strength-reduction.o): New dependencies. * passes.c (init_optimization_passes): Add pass_strength_reduction. gcc/testsuite: 2012-06-25 Bill Schmidt * gcc.dg/tree-ssa/slsr-1.c: New test. * gcc.dg/tree-ssa/slsr-2.c: Likewise. * gcc.dg/tree-ssa/slsr-3.c: Likewise. * gcc.dg/tree-ssa/slsr-4.c: Likewise. Index: gcc/tree-pass.h =================================================================== --- gcc/tree-pass.h (revision 188890) +++ gcc/tree-pass.h (working copy) @@ -452,6 +452,7 @@ extern struct gimple_opt_pass pass_tm_memopt; extern struct gimple_opt_pass pass_tm_edges; extern struct gimple_opt_pass pass_split_functions; extern struct gimple_opt_pass pass_feedback_split_functions; +extern struct gimple_opt_pass pass_strength_reduction; /* IPA Passes */ extern struct simple_ipa_opt_pass pass_ipa_lower_emutls; Index: gcc/testsuite/gcc.dg/tree-ssa/slsr-1.c =================================================================== --- gcc/testsuite/gcc.dg/tree-ssa/slsr-1.c (revision 0) +++ gcc/testsuite/gcc.dg/tree-ssa/slsr-1.c (revision 0) @@ -0,0 +1,20 @@ +/* { dg-do compile } */ +/* { dg-options "-O3 -fdump-tree-optimized" } */ + +extern void foo (int); + +void +f (int *p, unsigned int n) +{ + foo (*(p + n * 4)); + foo (*(p + 32 + n * 4)); + if (n > 3) + foo (*(p + 16 + n * 4)); + else + foo (*(p + 48 + n * 4)); +} + +/* { dg-final { scan-tree-dump-times "\\+ 128" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 64" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 192" 1 "optimized" } } */ +/* { dg-final { cleanup-tree-dump "optimized" } } */ Index: gcc/testsuite/gcc.dg/tree-ssa/slsr-2.c =================================================================== --- gcc/testsuite/gcc.dg/tree-ssa/slsr-2.c (revision 0) +++ gcc/testsuite/gcc.dg/tree-ssa/slsr-2.c (revision 0) @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* { dg-options "-O3 -fdump-tree-optimized" } */ + +extern void foo (int); + +void +f (int *p, int n) +{ + foo (*(p + n++ * 4)); + foo (*(p + 32 + n++ * 4)); + foo (*(p + 16 + n * 4)); +} + +/* { dg-final { scan-tree-dump-times "\\+ 144" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 96" 1 "optimized" } } */ +/* { dg-final { cleanup-tree-dump "optimized" } } */ Index: gcc/testsuite/gcc.dg/tree-ssa/slsr-3.c =================================================================== --- gcc/testsuite/gcc.dg/tree-ssa/slsr-3.c (revision 0) +++ gcc/testsuite/gcc.dg/tree-ssa/slsr-3.c (revision 0) @@ -0,0 +1,22 @@ +/* { dg-do compile } */ +/* { dg-options "-O3 -fdump-tree-optimized" } */ + +int +foo (int a[], int b[], int i) +{ + a[i] = b[i] + 2; + i++; + a[i] = b[i] + 2; + i++; + a[i] = b[i] + 2; + i++; + a[i] = b[i] + 2; + i++; + return i; +} + +/* { dg-final { scan-tree-dump-times "\\* 4" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 4" 2 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 8" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 12" 1 "optimized" } } */ +/* { dg-final { cleanup-tree-dump "optimized" } } */ Index: gcc/testsuite/gcc.dg/tree-ssa/slsr-4.c =================================================================== --- gcc/testsuite/gcc.dg/tree-ssa/slsr-4.c (revision 0) +++ gcc/testsuite/gcc.dg/tree-ssa/slsr-4.c (revision 0) @@ -0,0 +1,37 @@ +/* { dg-do compile } */ +/* { dg-options "-O3 -fdump-tree-slsr -fdump-tree-optimized" } */ + +void foo (int); + +int +f (int i) +{ + int x, y; + + x = i * 4; + y = x * 10; + foo (y); + + i = i + 5; + x = i * 4; + y = x * 10; + foo (y); + + i = i - 4; + x = i * 4; + y = x * 10; + foo (y); +} + +/* { dg-final { scan-tree-dump-times "\\* 4" 1 "slsr" } } */ +/* { dg-final { scan-tree-dump-times "\\* 10" 1 "slsr" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 20;" 1 "slsr" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 200" 1 "slsr" } } */ +/* { dg-final { scan-tree-dump-times "\\- 16;" 1 "slsr" } } */ +/* { dg-final { scan-tree-dump-times "\\- 160" 1 "slsr" } } */ +/* { dg-final { scan-tree-dump-times "\\* 4" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\* 10" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 200" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "\\+ 40" 1 "optimized" } } */ +/* { dg-final { cleanup-tree-dump "slsr" } } */ +/* { dg-final { cleanup-tree-dump "optimized" } } */ Index: gcc/tree-ssa-loop-ivopts.c =================================================================== --- gcc/tree-ssa-loop-ivopts.c (revision 188891) +++ gcc/tree-ssa-loop-ivopts.c (working copy) @@ -856,7 +856,7 @@ htab_inv_expr_hash (const void *ent) /* Allocate data structures for the cost model. */ -static void +void initialize_costs (void) { mult_costs[0] = htab_create (100, mbc_entry_hash, mbc_entry_eq, free); @@ -866,7 +866,7 @@ initialize_costs (void) /* Release data structures for the cost model. */ -static void +void finalize_costs (void) { cost_tables_exist = false; Index: gcc/timevar.def =================================================================== --- gcc/timevar.def (revision 188890) +++ gcc/timevar.def (working copy) @@ -257,6 +257,7 @@ DEFTIMEVAR (TV_TREE_IFCOMBINE , "tree if-co DEFTIMEVAR (TV_TREE_UNINIT , "uninit var analysis") DEFTIMEVAR (TV_PLUGIN_INIT , "plugin initialization") DEFTIMEVAR (TV_PLUGIN_RUN , "plugin execution") +DEFTIMEVAR (TV_GIMPLE_SLSR , "straight-line strength reduction") /* Everything else in rest_of_compilation not included above. */ DEFTIMEVAR (TV_EARLY_LOCAL , "early local passes") Index: gcc/gimple-ssa-strength-reduction.c =================================================================== --- gcc/gimple-ssa-strength-reduction.c (revision 0) +++ gcc/gimple-ssa-strength-reduction.c (revision 0) @@ -0,0 +1,1523 @@ +/* Straight-line strength reduction. + Copyright (C) 2012 Free Software Foundation, Inc. + Contributed by Bill Schmidt, IBM + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation; either version 3, or (at your option) any later +version. + +GCC is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING3. If not see +. */ + +/* There are many algorithms for performing strength reduction on + loops. This is not one of them. IVOPTS handles strength reduction + of induction variables just fine. This pass is intended to pick + up the crumbs it leaves behind, by considering opportunities for + strength reduction along dominator paths. + + Strength reduction will be implemented in four stages, gradually + adding more complex candidates: + + 1) Explicit multiplies, known constant multipliers, no + conditional increments. (complete) + 2) Explicit multiplies, unknown constant multipliers, + no conditional increments. (data gathering complete, + replacements pending) + 3) Implicit multiplies in addressing expressions. (pending) + 4) Explicit multiplies, conditional increments. (pending) + + It would also be possible to apply strength reduction to divisions + and modulos, but such opportunities are relatively uncommon. + + Strength reduction is also currently restricted to integer operations. + If desired, it could be extended to floating-point operations under + control of something like -funsafe-math-optimizations. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tree.h" +#include "gimple.h" +#include "basic-block.h" +#include "tree-pass.h" +#include "timevar.h" +#include "cfgloop.h" +#include "tree-pretty-print.h" +#include "gimple-pretty-print.h" +#include "tree-flow.h" +#include "domwalk.h" +#include "pointer-set.h" + +/* Information about a strength reduction candidate. Each statement + in the candidate table represents an expression of one of the + following forms (the special case of CAND_REF will be described + later): + + (CAND_MULT) S1: X = (B + i) * S + (CAND_ADD) S1: X = B + (i * S) + + Here X and B are SSA names, i is an integer constant, and S is + either an SSA name or a constant. We call B the "base," i the + "index", and S the "stride." + + Any statement S0 that dominates S1 and is of the form: + + (CAND_MULT) S0: Y = (B + i') * S + (CAND_ADD) S0: Y = B + (i' * S) + + is called a "basis" for S1. In both cases, S1 may be replaced by + + S1': X = Y + (i - i') * S, + + where (i - i') * S is folded to the extent possible. + + All gimple statements are visited in dominator order, and each + statement that may contribute to one of the forms of S1 above is + given at least one entry in the candidate table. Such statements + include addition, pointer addition, subtraction, multiplication, + negation, copies, and nontrivial type casts. If a statement may + represent more than one expression of the forms of S1 above, + multiple "interpretations" are stored in the table and chained + together. Examples: + + * An add of two SSA names may treat either operand as the base. + * A multiply of two SSA names, likewise. + * A copy or cast may be thought of as either a CAND_MULT with + i = 0 and S = 1, or as a CAND_ADD with i = 0 or S = 0. + + Candidate records are allocated from an obstack. They are addressed + both from a hash table keyed on S1, and from a vector of candidate + pointers arranged in predominator order. + + Opportunity note + ---------------- + Currently we don't recognize: + + S0: Y = (S * i') - B + S1: X = (S * i) - B + + as a strength reduction opportunity, even though this S1 would + also be replaceable by the S1' above. This can be added if it + comes up in practice. */ + + +/* Index into the candidate vector, offset by 1. VECs are zero-based, + while cand_idx's are one-based, with zero indicating null. */ +typedef unsigned cand_idx; + +/* The kind of candidate. */ +enum cand_kind +{ + CAND_MULT, + CAND_ADD +}; + +struct slsr_cand_d +{ + /* The candidate statement S1. */ + gimple cand_stmt; + + /* The base SSA name B. */ + tree base_name; + + /* The stride S. */ + tree stride; + + /* The index constant i. */ + double_int index; + + /* The type of the candidate. This is normally the type of base_name, + but casts may have occurred when combining feeding instructions. + A candidate can only be a basis for candidates of the same final type. */ + tree cand_type; + + /* The kind of candidate (CAND_MULT, etc.). */ + enum cand_kind kind; + + /* Index of this candidate in the candidate vector. */ + cand_idx cand_num; + + /* Index of the next candidate record for the same statement. + A statement may be useful in more than one way (e.g., due to + commutativity). So we can have multiple "interpretations" + of a statement. */ + cand_idx next_interp; + + /* Index of the basis statement S0, if any, in the candidate vector. */ + cand_idx basis; + + /* First candidate for which this candidate is a basis, if one exists. */ + cand_idx dependent; + + /* Next candidate having the same basis as this one. */ + cand_idx sibling; + + /* If this is a conditional candidate, the defining PHI statement + for the base SSA name B. For future use; always NULL for now. */ + gimple def_phi; + + /* Savings that can be expected from eliminating dead code if this + candidate is replaced. */ + int dead_savings; +}; + +typedef struct slsr_cand_d slsr_cand, *slsr_cand_t; +typedef const struct slsr_cand_d *const_slsr_cand_t; + +/* Pointers to candidates are chained together as part of a mapping + from SSA names to the candidates that use them as a base name. */ + +struct cand_chain_d +{ + /* SSA name that serves as a base name for the chain of candidates. */ + tree base_name; + + /* Pointer to a candidate. */ + slsr_cand_t cand; + + /* Chain pointer. */ + struct cand_chain_d *next; + +}; + +typedef struct cand_chain_d cand_chain, *cand_chain_t; +typedef const struct cand_chain_d *const_cand_chain_t; + +/* Candidates are maintained in a vector. If candidate X dominates + candidate Y, then X appears before Y in the vector; but the + converse does not necessarily hold. */ +DEF_VEC_P (slsr_cand_t); +DEF_VEC_ALLOC_P (slsr_cand_t, heap); +static VEC (slsr_cand_t, heap) *cand_vec; + +enum cost_consts +{ + COST_NEUTRAL = 0, + COST_INFINITE = 1000 +}; + +/* Pointer map embodying a mapping from statements to candidates. */ +static struct pointer_map_t *stmt_cand_map; + +/* Obstack for candidates. */ +static struct obstack cand_obstack; + +/* Array mapping from base SSA names to chains of candidates. */ +static cand_chain_t *base_cand_map; + +/* Obstack for candidate chains. */ +static struct obstack chain_obstack; + +/* Produce a pointer to the IDX'th candidate in the candidate vector. */ + +static slsr_cand_t +lookup_cand (cand_idx idx) +{ + return VEC_index (slsr_cand_t, cand_vec, idx - 1); +} + +/* Use the base name from candidate C to look for possible candidates + that can serve as a basis for C. Each potential basis must also + appear in a block that dominates the candidate statement and have + the same stride and type. If more than one possible basis exists, + the one with highest index in the vector is chosen; this will be + the most immediately dominating basis. */ + +static int +find_basis_for_candidate (slsr_cand_t c) +{ + cand_chain_t chain; + slsr_cand_t basis = NULL; + + gcc_assert (TREE_CODE (c->base_name) == SSA_NAME); + chain = base_cand_map[SSA_NAME_VERSION (c->base_name)]; + + for (; chain; chain = chain->next) + { + slsr_cand_t one_basis = chain->cand; + + if (one_basis->kind != c->kind + || !operand_equal_p (one_basis->stride, c->stride, 0) + || !types_compatible_p (one_basis->cand_type, c->cand_type) + || !dominated_by_p (CDI_DOMINATORS, + gimple_bb (c->cand_stmt), + gimple_bb (one_basis->cand_stmt))) + continue; + + if (!basis || basis->cand_num < one_basis->cand_num) + basis = one_basis; + } + + if (basis) + { + c->sibling = basis->dependent; + basis->dependent = c->cand_num; + return basis->cand_num; + } + + return 0; +} + +/* Record a mapping from the base name of C to C itself, indicating that + C may potentially serve as a basis using that base name. */ + +static void +record_potential_basis (slsr_cand_t c) +{ + cand_chain_t node, head; + int index; + + node = (cand_chain_t) obstack_alloc (&chain_obstack, sizeof (cand_chain)); + node->base_name = c->base_name; + node->cand = c; + node->next = NULL; + index = SSA_NAME_VERSION (c->base_name); + head = base_cand_map[index]; + + if (head) + { + node->next = head->next; + head->next = node; + } + else + base_cand_map[index] = node; +} + +/* Allocate storage for a new candidate and initialize its fields. + Attempt to find a basis for the candidate. */ + +static slsr_cand_t +alloc_cand_and_find_basis (enum cand_kind kind, gimple gs, tree base, + double_int index, tree stride, tree ctype, + unsigned savings) +{ + slsr_cand_t c = (slsr_cand_t) obstack_alloc (&cand_obstack, + sizeof (slsr_cand)); + c->cand_stmt = gs; + c->base_name = base; + c->stride = stride; + c->index = index; + c->cand_type = ctype; + c->kind = kind; + c->cand_num = VEC_length (slsr_cand_t, cand_vec) + 1; + c->next_interp = 0; + c->dependent = 0; + c->sibling = 0; + c->def_phi = NULL; + c->dead_savings = savings; + + VEC_safe_push (slsr_cand_t, heap, cand_vec, c); + c->basis = find_basis_for_candidate (c); + record_potential_basis (c); + + return c; +} + +/* Determine the target cost of statement GS when compiling according + to SPEED. */ + +static int +stmt_cost (gimple gs, bool speed) +{ + tree lhs, rhs1, rhs2; + enum machine_mode lhs_mode; + + gcc_assert (is_gimple_assign (gs)); + lhs = gimple_assign_lhs (gs); + rhs1 = gimple_assign_rhs1 (gs); + lhs_mode = TYPE_MODE (TREE_TYPE (lhs)); + + switch (gimple_assign_rhs_code (gs)) + { + case MULT_EXPR: + rhs2 = gimple_assign_rhs2 (gs); + + if (host_integerp (rhs2, 0)) + return multiply_by_const_cost (TREE_INT_CST_LOW (rhs2), lhs_mode, + speed); + + gcc_assert (TREE_CODE (rhs1) != INTEGER_CST); + return multiply_regs_cost (TYPE_MODE (TREE_TYPE (lhs)), speed); + + case PLUS_EXPR: + case POINTER_PLUS_EXPR: + case MINUS_EXPR: + rhs2 = gimple_assign_rhs2 (gs); + + if (host_integerp (rhs2, 0)) + return add_const_cost (TYPE_MODE (TREE_TYPE (rhs1)), speed); + + gcc_assert (TREE_CODE (rhs1) != INTEGER_CST); + return add_regs_cost (lhs_mode, speed); + + case NEGATE_EXPR: + return negate_reg_cost (lhs_mode, speed); + + case NOP_EXPR: + return extend_or_trunc_reg_cost (TREE_TYPE (lhs), TREE_TYPE (rhs1), + speed); + + /* Note that we don't assign costs to copies that in most cases + will go away. */ + default: + ; + } + + gcc_unreachable (); + return 0; +} + +/* Look up the defining statement for BASE_IN and return a pointer + to its candidate in the candidate table, if any; otherwise NULL. + Only CAND_ADD and CAND_MULT candidates are returned. */ + +static slsr_cand_t +base_cand_from_table (tree base_in) +{ + slsr_cand_t *result; + + gimple def = SSA_NAME_DEF_STMT (base_in); + if (!def) + return (slsr_cand_t) NULL; + + result = (slsr_cand_t *) pointer_map_contains (stmt_cand_map, def); + if (!result) + return (slsr_cand_t) NULL; + + return *result; +} + +/* Add an entry to the statement-to-candidate mapping. */ + +static void +add_cand_for_stmt (gimple gs, slsr_cand_t c) +{ + void **slot = pointer_map_insert (stmt_cand_map, gs); + gcc_assert (!*slot); + *slot = c; +} + +/* Create a candidate entry for a statement GS, where GS multiplies + two SSA names BASE_IN and STRIDE_IN. Propagate any known information + about the two SSA names into the new candidate. Return the new + candidate. */ + +static slsr_cand_t +create_mul_ssa_cand (gimple gs, tree base_in, tree stride_in, bool speed) +{ + tree base = NULL_TREE, stride = NULL_TREE, ctype = NULL_TREE; + double_int index; + unsigned savings = 0; + slsr_cand_t c; + slsr_cand_t base_cand = base_cand_from_table (base_in); + + /* Look at all interpretations of the base candidate, if necessary, + to find information to propagate into this candidate. */ + while (base_cand && !base) + { + + if (base_cand->kind == CAND_MULT + && operand_equal_p (base_cand->stride, integer_one_node, 0)) + { + /* Y = (B + i') * 1 + X = Y * Z + ================ + X = (B + i') * Z */ + base = base_cand->base_name; + index = base_cand->index; + stride = stride_in; + ctype = base_cand->cand_type; + if (has_single_use (base_in)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + } + else if (base_cand->kind == CAND_ADD + && TREE_CODE (base_cand->stride) == INTEGER_CST) + { + /* Y = B + (i' * S), S constant + X = Y * Z + ============================ + X = B + ((i' * S) * Z) */ + base = base_cand->base_name; + index = double_int_mul (base_cand->index, + tree_to_double_int (base_cand->stride)); + stride = stride_in; + ctype = base_cand->cand_type; + if (has_single_use (base_in)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + } + + if (base_cand->next_interp) + base_cand = lookup_cand (base_cand->next_interp); + else + base_cand = NULL; + } + + if (!base) + { + /* No interpretations had anything useful to propagate, so + produce X = (Y + 0) * Z. */ + base = base_in; + index = double_int_zero; + stride = stride_in; + ctype = TREE_TYPE (SSA_NAME_VAR (base_in)); + } + + c = alloc_cand_and_find_basis (CAND_MULT, gs, base, index, stride, + ctype, savings); + return c; +} + +/* Create a candidate entry for a statement GS, where GS multiplies + SSA name BASE_IN by constant STRIDE_IN. Propagate any known + information about BASE_IN into the new candidate. Return the new + candidate. */ + +static slsr_cand_t +create_mul_imm_cand (gimple gs, tree base_in, tree stride_in, bool speed) +{ + tree base = NULL_TREE, stride = NULL_TREE, ctype = NULL_TREE; + double_int index, temp; + unsigned savings = 0; + slsr_cand_t c; + slsr_cand_t base_cand = base_cand_from_table (base_in); + + /* Look at all interpretations of the base candidate, if necessary, + to find information to propagate into this candidate. */ + while (base_cand && !base) + { + if (base_cand->kind == CAND_MULT + && TREE_CODE (base_cand->stride) == INTEGER_CST) + { + /* Y = (B + i') * S, S constant + X = Y * c + ============================ + X = (B + i') * (S * c) */ + base = base_cand->base_name; + index = base_cand->index; + temp = double_int_mul (tree_to_double_int (base_cand->stride), + tree_to_double_int (stride_in)); + stride = double_int_to_tree (TREE_TYPE (stride_in), temp); + ctype = base_cand->cand_type; + if (has_single_use (base_in)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + } + else if (base_cand->kind == CAND_ADD + && operand_equal_p (base_cand->stride, integer_one_node, 0)) + { + /* Y = B + (i' * 1) + X = Y * c + =========================== + X = (B + i') * c */ + base = base_cand->base_name; + index = base_cand->index; + stride = stride_in; + ctype = base_cand->cand_type; + if (has_single_use (base_in)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + } + else if (base_cand->kind == CAND_ADD + && double_int_one_p (base_cand->index) + && TREE_CODE (base_cand->stride) == INTEGER_CST) + { + /* Y = B + (1 * S), S constant + X = Y * c + =========================== + X = (B + S) * c */ + base = base_cand->base_name; + index = tree_to_double_int (base_cand->stride); + stride = stride_in; + ctype = base_cand->cand_type; + if (has_single_use (base_in)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + } + + if (base_cand->next_interp) + base_cand = lookup_cand (base_cand->next_interp); + else + base_cand = NULL; + } + + if (!base) + { + /* No interpretations had anything useful to propagate, so + produce X = (Y + 0) * c. */ + base = base_in; + index = double_int_zero; + stride = stride_in; + ctype = TREE_TYPE (SSA_NAME_VAR (base_in)); + } + + c = alloc_cand_and_find_basis (CAND_MULT, gs, base, index, stride, + ctype, savings); + return c; +} + +/* Given GS which is a multiply of scalar integers, make an appropriate + entry in the candidate table. If this is a multiply of two SSA names, + create two CAND_MULT interpretations and attempt to find a basis for + each of them. Otherwise, create a single CAND_MULT and attempt to + find a basis. */ + +static void +slsr_process_mul (gimple gs, tree rhs1, tree rhs2, bool speed) +{ + slsr_cand_t c, c2; + + /* If this is a multiply of an SSA name with itself, it is highly + unlikely that we will get a strength reduction opportunity, so + don't record it as a candidate. This simplifies the logic for + finding a basis, so if this is removed that must be considered. */ + if (rhs1 == rhs2) + return; + + if (TREE_CODE (rhs2) == SSA_NAME) + { + /* Record an interpretation of this statement in the candidate table + assuming RHS1 is the base name and RHS2 is the stride. */ + c = create_mul_ssa_cand (gs, rhs1, rhs2, speed); + + /* Add the first interpretation to the statement-candidate mapping. */ + add_cand_for_stmt (gs, c); + + /* Record another interpretation of this statement assuming RHS1 + is the stride and RHS2 is the base name. */ + c2 = create_mul_ssa_cand (gs, rhs2, rhs1, speed); + c->next_interp = c2->cand_num; + } + else + { + /* Record an interpretation for the multiply-immediate. */ + c = create_mul_imm_cand (gs, rhs1, rhs2, speed); + + /* Add the interpretation to the statement-candidate mapping. */ + add_cand_for_stmt (gs, c); + } +} + +/* Create a candidate entry for a statement GS, where GS adds two + SSA names BASE_IN and ADDEND_IN if SUBTRACT_P is false, and + subtracts ADDEND_IN from BASE_IN otherwise. Propagate any known + information about the two SSA names into the new candidate. + Return the new candidate. */ + +static slsr_cand_t +create_add_ssa_cand (gimple gs, tree base_in, tree addend_in, + bool subtract_p, bool speed) +{ + tree base = NULL_TREE, stride = NULL_TREE, ctype = NULL; + double_int index; + unsigned savings = 0; + slsr_cand_t c; + slsr_cand_t base_cand = base_cand_from_table (base_in); + slsr_cand_t addend_cand = base_cand_from_table (addend_in); + + /* The most useful transformation is a multiply-immediate feeding + an add or subtract. Look for that first. */ + while (addend_cand && !base) + { + if (addend_cand->kind == CAND_MULT + && double_int_zero_p (addend_cand->index) + && TREE_CODE (addend_cand->stride) == INTEGER_CST) + { + /* Z = (B + 0) * S, S constant + X = Y +/- Z + =========================== + X = Y + ((+/-1 * S) * B) */ + base = base_in; + index = tree_to_double_int (addend_cand->stride); + if (subtract_p) + index = double_int_neg (index); + stride = addend_cand->base_name; + ctype = TREE_TYPE (SSA_NAME_VAR (base_in)); + if (has_single_use (addend_in)) + savings = (addend_cand->dead_savings + + stmt_cost (addend_cand->cand_stmt, speed)); + } + + if (addend_cand->next_interp) + addend_cand = lookup_cand (addend_cand->next_interp); + else + addend_cand = NULL; + } + + while (base_cand && !base) + { + if (base_cand->kind == CAND_ADD + && (double_int_zero_p (base_cand->index) + || operand_equal_p (base_cand->stride, + integer_zero_node, 0))) + { + /* Y = B + (i' * S), i' * S = 0 + X = Y +/- Z + ============================ + X = B + (+/-1 * Z) */ + base = base_cand->base_name; + index = subtract_p ? double_int_minus_one : double_int_one; + stride = addend_in; + ctype = base_cand->cand_type; + if (has_single_use (base_in)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + } + else if (subtract_p) + { + slsr_cand_t subtrahend_cand = base_cand_from_table (addend_in); + + while (subtrahend_cand && !base) + { + if (subtrahend_cand->kind == CAND_MULT + && double_int_zero_p (subtrahend_cand->index) + && TREE_CODE (subtrahend_cand->stride) == INTEGER_CST) + { + /* Z = (B + 0) * S, S constant + X = Y - Z + =========================== + Value: X = Y + ((-1 * S) * B) */ + base = base_in; + index = tree_to_double_int (subtrahend_cand->stride); + index = double_int_neg (index); + stride = subtrahend_cand->base_name; + ctype = TREE_TYPE (SSA_NAME_VAR (base_in)); + if (has_single_use (addend_in)) + savings = (subtrahend_cand->dead_savings + + stmt_cost (subtrahend_cand->cand_stmt, speed)); + } + + if (subtrahend_cand->next_interp) + subtrahend_cand = lookup_cand (subtrahend_cand->next_interp); + else + subtrahend_cand = NULL; + } + } + + if (base_cand->next_interp) + base_cand = lookup_cand (base_cand->next_interp); + else + base_cand = NULL; + } + + if (!base) + { + /* No interpretations had anything useful to propagate, so + produce X = Y + (1 * Z). */ + base = base_in; + index = subtract_p ? double_int_minus_one : double_int_one; + stride = addend_in; + ctype = TREE_TYPE (SSA_NAME_VAR (base_in)); + } + + c = alloc_cand_and_find_basis (CAND_ADD, gs, base, index, stride, + ctype, savings); + return c; +} + +/* Create a candidate entry for a statement GS, where GS adds SSA + name BASE_IN to constant INDEX_IN. Propagate any known information + about BASE_IN into the new candidate. Return the new candidate. */ + +static slsr_cand_t +create_add_imm_cand (gimple gs, tree base_in, double_int index_in, bool speed) +{ + enum cand_kind kind = CAND_ADD; + tree base = NULL_TREE, stride = NULL_TREE, ctype = NULL_TREE; + double_int index, multiple; + unsigned savings = 0; + slsr_cand_t c; + slsr_cand_t base_cand = base_cand_from_table (base_in); + + while (base_cand && !base) + { + bool unsigned_p = TYPE_UNSIGNED (TREE_TYPE (base_cand->stride)); + + if (TREE_CODE (base_cand->stride) == INTEGER_CST + && double_int_multiple_of (index_in, + tree_to_double_int (base_cand->stride), + unsigned_p, + &multiple)) + { + /* Y = (B + i') * S, S constant, c = kS for some integer k + X = Y + c + ============================ + X = (B + (i'+ k)) * S + OR + Y = B + (i' * S), S constant, c = kS for some integer k + X = Y + c + ============================ + X = (B + (i'+ k)) * S */ + kind = base_cand->kind; + base = base_cand->base_name; + index = double_int_add (base_cand->index, multiple); + stride = base_cand->stride; + ctype = base_cand->cand_type; + if (has_single_use (base_in)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + } + + if (base_cand->next_interp) + base_cand = lookup_cand (base_cand->next_interp); + else + base_cand = NULL; + } + + if (!base) + { + /* No interpretations had anything useful to propagate, so + produce X = Y + (c * 1). */ + kind = CAND_ADD; + base = base_in; + index = index_in; + stride = integer_one_node; + ctype = TREE_TYPE (SSA_NAME_VAR (base_in)); + } + + c = alloc_cand_and_find_basis (kind, gs, base, index, stride, + ctype, savings); + return c; +} + +/* Given GS which is an add or subtract of scalar integers or pointers, + make at least one appropriate entry in the candidate table. */ + +static void +slsr_process_add (gimple gs, tree rhs1, tree rhs2, bool speed) +{ + bool subtract_p = gimple_assign_rhs_code (gs) == MINUS_EXPR; + slsr_cand_t c = NULL, c2; + + if (TREE_CODE (rhs2) == SSA_NAME) + { + /* First record an interpretation assuming RHS1 is the base name + and RHS2 is the stride. But it doesn't make sense for the + stride to be a pointer, so don't record a candidate in that case. */ + if (!POINTER_TYPE_P (TREE_TYPE (SSA_NAME_VAR (rhs2)))) + { + c = create_add_ssa_cand (gs, rhs1, rhs2, subtract_p, speed); + + /* Add the first interpretation to the statement-candidate + mapping. */ + add_cand_for_stmt (gs, c); + } + + /* If the two RHS operands are identical, or this is a subtract, + we're done. */ + if (operand_equal_p (rhs1, rhs2, 0) || subtract_p) + return; + + /* Otherwise, record another interpretation assuming RHS2 is the + base name and RHS1 is the stride, again provided that the + stride is not a pointer. */ + if (!POINTER_TYPE_P (TREE_TYPE (SSA_NAME_VAR (rhs1)))) + { + c2 = create_add_ssa_cand (gs, rhs2, rhs1, false, speed); + if (c) + c->next_interp = c2->cand_num; + else + add_cand_for_stmt (gs, c2); + } + } + else + { + double_int index; + + /* Record an interpretation for the add-immediate. */ + index = tree_to_double_int (rhs2); + if (subtract_p) + index = double_int_neg (index); + + c = create_add_imm_cand (gs, rhs1, index, speed); + + /* Add the interpretation to the statement-candidate mapping. */ + add_cand_for_stmt (gs, c); + } +} + +/* Given GS which is a negate of a scalar integer, make an appropriate + entry in the candidate table. A negate is equivalent to a multiply + by -1. */ + +static void +slsr_process_neg (gimple gs, tree rhs1, bool speed) +{ + /* Record a CAND_MULT interpretation for the multiply by -1. */ + slsr_cand_t c = create_mul_imm_cand (gs, rhs1, integer_minus_one_node, speed); + + /* Add the interpretation to the statement-candidate mapping. */ + add_cand_for_stmt (gs, c); +} + +/* Return TRUE if GS is a statement that defines an SSA name from + a conversion and is legal for us to combine with an add and multiply + in the candidate table. For example, suppose we have: + + A = B + i; + C = (type) A; + D = C * S; + + Without the type-cast, we would create a CAND_MULT for D with base B, + index i, and stride S. We want to record this candidate only if it + is equivalent to apply the type cast following the multiply: + + A = B + i; + E = A * S; + D = (type) E; + + We will record the type with the candidate for D. This allows us + to use a similar previous candidate as a basis. If we have earlier seen + + A' = B + i'; + C' = (type) A'; + D' = C' * S; + + we can replace D with + + D = D' + (i - i') * S; + + But if moving the type-cast would change semantics, we mustn't do this. + + This is legitimate for casts from a non-wrapping integral type to + any integral type of the same or larger size. It is not legitimate + to convert a wrapping type to a non-wrapping type, or to a wrapping + type of a different size. I.e., with a wrapping type, we must + assume that the addition B + i could wrap, in which case performing + the multiply before or after one of the "illegal" type casts will + have different semantics. */ + +static bool +legal_cast_p (gimple gs, tree rhs) +{ + tree lhs, lhs_type, rhs_type; + unsigned lhs_size, rhs_size; + bool lhs_wraps, rhs_wraps; + + if (!is_gimple_assign (gs) + || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (gs))) + return false; + + lhs = gimple_assign_lhs (gs); + lhs_type = TREE_TYPE (lhs); + rhs_type = TREE_TYPE (rhs); + lhs_size = TYPE_PRECISION (lhs_type); + rhs_size = TYPE_PRECISION (rhs_type); + lhs_wraps = TYPE_OVERFLOW_WRAPS (lhs_type); + rhs_wraps = TYPE_OVERFLOW_WRAPS (rhs_type); + + if (lhs_size < rhs_size + || (rhs_wraps && !lhs_wraps) + || (rhs_wraps && lhs_wraps && rhs_size != lhs_size)) + return false; + + return true; +} + +/* Given GS which is a cast to a scalar integer type, determine whether + the cast is legal for strength reduction. If so, make at least one + appropriate entry in the candidate table. */ + +static void +slsr_process_cast (gimple gs, tree rhs1, bool speed) +{ + tree lhs, ctype; + slsr_cand_t base_cand, c, c2; + unsigned savings = 0; + + if (!legal_cast_p (gs, rhs1)) + return; + + lhs = gimple_assign_lhs (gs); + base_cand = base_cand_from_table (rhs1); + ctype = TREE_TYPE (lhs); + + if (base_cand) + { + while (base_cand) + { + /* Propagate all data from the base candidate except the type, + which comes from the cast, and the base candidate's cast, + which is no longer applicable. */ + if (has_single_use (rhs1)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + + c = alloc_cand_and_find_basis (base_cand->kind, gs, + base_cand->base_name, + base_cand->index, base_cand->stride, + ctype, savings); + if (base_cand->next_interp) + base_cand = lookup_cand (base_cand->next_interp); + else + base_cand = NULL; + } + } + else + { + /* If nothing is known about the RHS, create fresh CAND_ADD and + CAND_MULT interpretations: + + X = Y + (0 * 1) + X = (Y + 0) * 1 + + The first of these is somewhat arbitrary, but the choice of + 1 for the stride simplifies the logic for propagating casts + into their uses. */ + c = alloc_cand_and_find_basis (CAND_ADD, gs, rhs1, double_int_zero, + integer_one_node, ctype, 0); + c2 = alloc_cand_and_find_basis (CAND_MULT, gs, rhs1, double_int_zero, + integer_one_node, ctype, 0); + c->next_interp = c2->cand_num; + } + + /* Add the first (or only) interpretation to the statement-candidate + mapping. */ + add_cand_for_stmt (gs, c); +} + +/* Given GS which is a copy of a scalar integer type, make at least one + appropriate entry in the candidate table. + + This interface is included for completeness, but is unnecessary + if this pass immediately follows a pass that performs copy + propagation, such as DOM. */ + +static void +slsr_process_copy (gimple gs, tree rhs1, bool speed) +{ + slsr_cand_t base_cand, c, c2; + unsigned savings = 0; + + base_cand = base_cand_from_table (rhs1); + + if (base_cand) + { + while (base_cand) + { + /* Propagate all data from the base candidate. */ + if (has_single_use (rhs1)) + savings = (base_cand->dead_savings + + stmt_cost (base_cand->cand_stmt, speed)); + + c = alloc_cand_and_find_basis (base_cand->kind, gs, + base_cand->base_name, + base_cand->index, base_cand->stride, + base_cand->cand_type, savings); + if (base_cand->next_interp) + base_cand = lookup_cand (base_cand->next_interp); + else + base_cand = NULL; + } + } + else + { + /* If nothing is known about the RHS, create fresh CAND_ADD and + CAND_MULT interpretations: + + X = Y + (0 * 1) + X = (Y + 0) * 1 + + The first of these is somewhat arbitrary, but the choice of + 1 for the stride simplifies the logic for propagating casts + into their uses. */ + c = alloc_cand_and_find_basis (CAND_ADD, gs, rhs1, double_int_zero, + integer_one_node, TREE_TYPE (rhs1), 0); + c2 = alloc_cand_and_find_basis (CAND_MULT, gs, rhs1, double_int_zero, + integer_one_node, TREE_TYPE (rhs1), 0); + c->next_interp = c2->cand_num; + } + + /* Add the first (or only) interpretation to the statement-candidate + mapping. */ + add_cand_for_stmt (gs, c); +} + +/* Find strength-reduction candidates in block BB. */ + +static void +find_candidates_in_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, + basic_block bb) +{ + bool speed = optimize_bb_for_speed_p (bb); + gimple_stmt_iterator gsi; + + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple gs = gsi_stmt (gsi); + + if (is_gimple_assign (gs) + && SCALAR_INT_MODE_P (TYPE_MODE (TREE_TYPE (gimple_assign_lhs (gs))))) + { + tree rhs1 = NULL_TREE, rhs2 = NULL_TREE; + + switch (gimple_assign_rhs_code (gs)) + { + case MULT_EXPR: + case PLUS_EXPR: + rhs1 = gimple_assign_rhs1 (gs); + rhs2 = gimple_assign_rhs2 (gs); + gcc_assert (TREE_CODE (rhs1) == SSA_NAME); + break; + + /* Possible future opportunity: rhs1 of a ptr+ can be + an ADDR_EXPR. */ + case POINTER_PLUS_EXPR: + case MINUS_EXPR: + rhs2 = gimple_assign_rhs2 (gs); + /* Fall-through. */ + + case NOP_EXPR: + case MODIFY_EXPR: + case NEGATE_EXPR: + rhs1 = gimple_assign_rhs1 (gs); + if (TREE_CODE (rhs1) != SSA_NAME) + continue; + break; + + default: + ; + } + + switch (gimple_assign_rhs_code (gs)) + { + case MULT_EXPR: + slsr_process_mul (gs, rhs1, rhs2, speed); + break; + + case PLUS_EXPR: + case POINTER_PLUS_EXPR: + case MINUS_EXPR: + slsr_process_add (gs, rhs1, rhs2, speed); + break; + + case NEGATE_EXPR: + slsr_process_neg (gs, rhs1, speed); + break; + + case NOP_EXPR: + slsr_process_cast (gs, rhs1, speed); + break; + + case MODIFY_EXPR: + slsr_process_copy (gs, rhs1, speed); + break; + + default: + ; + } + } + } +} + +/* Dump a candidate for debug. */ + +static void +dump_candidate (slsr_cand_t c) +{ + fprintf (dump_file, "%3d [%d] ", c->cand_num, + gimple_bb (c->cand_stmt)->index); + print_gimple_stmt (dump_file, c->cand_stmt, 0, 0); + switch (c->kind) + { + case CAND_MULT: + fputs (" MULT : (", dump_file); + print_generic_expr (dump_file, c->base_name, 0); + fputs (" + ", dump_file); + dump_double_int (dump_file, c->index, false); + fputs (") * ", dump_file); + print_generic_expr (dump_file, c->stride, 0); + fputs (" : ", dump_file); + break; + case CAND_ADD: + fputs (" ADD : ", dump_file); + print_generic_expr (dump_file, c->base_name, 0); + fputs (" + (", dump_file); + dump_double_int (dump_file, c->index, false); + fputs (" * ", dump_file); + print_generic_expr (dump_file, c->stride, 0); + fputs (") : ", dump_file); + break; + default: + gcc_unreachable (); + } + print_generic_expr (dump_file, c->cand_type, 0); + fprintf (dump_file, "\n basis: %d dependent: %d sibling: %d\n", + c->basis, c->dependent, c->sibling); + fprintf (dump_file, " next-interp: %d dead-savings: %d\n", + c->next_interp, c->dead_savings); + if (c->def_phi) + { + fputs (" phi: ", dump_file); + print_gimple_stmt (dump_file, c->def_phi, 0, 0); + } + fputs ("\n", dump_file); +} + +/* Dump the candidate vector for debug. */ + +static void +dump_cand_vec (void) +{ + unsigned i; + slsr_cand_t c; + + fprintf (dump_file, "\nStrength reduction candidate vector:\n\n"); + + FOR_EACH_VEC_ELT (slsr_cand_t, cand_vec, i, c) + dump_candidate (c); +} + +/* Dump the candidate chains. */ + +static void +dump_cand_chains (void) +{ + unsigned i; + + fprintf (dump_file, "\nStrength reduction candidate chains:\n\n"); + + for (i = 0; i < num_ssa_names; i++) + { + const_cand_chain_t chain = base_cand_map[i]; + + if (chain) + { + cand_chain_t p; + + print_generic_expr (dump_file, chain->base_name, 0); + fprintf (dump_file, " -> %d", chain->cand->cand_num); + + for (p = chain->next; p; p = p->next) + fprintf (dump_file, " -> %d", p->cand->cand_num); + + fputs ("\n", dump_file); + } + } + + fputs ("\n", dump_file); +} + + +/* Recursive helper for unconditional_cands_with_known_stride_p. + Returns TRUE iff C, its siblings, and its dependents are all + unconditional candidates. */ + +static bool +unconditional_cands (slsr_cand_t c) +{ + if (c->def_phi) + return false; + + if (c->sibling && !unconditional_cands (lookup_cand (c->sibling))) + return false; + + if (c->dependent && !unconditional_cands (lookup_cand (c->dependent))) + return false; + + return true; +} + +/* Determine whether or not the tree of candidates rooted at + ROOT consists entirely of unconditional increments with + an INTEGER_CST stride. */ + +static bool +unconditional_cands_with_known_stride_p (slsr_cand_t root) +{ + /* The stride is identical for all related candidates, so + check it once. */ + if (TREE_CODE (root->stride) != INTEGER_CST) + return false; + + return unconditional_cands (lookup_cand (root->dependent)); +} + +/* Calculate the increment required for candidate C relative to + its basis. */ + +static double_int +cand_increment (slsr_cand_t c) +{ + slsr_cand_t basis; + + /* If the candidate doesn't have a basis, just return its own + index. This is useful in record_increments to help us find + an existing initializer. */ + if (!c->basis) + return c->index; + + basis = lookup_cand (c->basis); + gcc_assert (operand_equal_p (c->base_name, basis->base_name, 0)); + return double_int_sub (c->index, basis->index); +} + +/* Return TRUE iff candidate C has already been replaced under + another interpretation. */ + +static inline bool +cand_already_replaced (slsr_cand_t c) +{ + return (gimple_bb (c->cand_stmt) == 0); +} + +/* Helper routine for replace_dependents, doing the work for a + single candidate C. */ + +static void +replace_dependent (slsr_cand_t c, enum tree_code cand_code) +{ + double_int stride = tree_to_double_int (c->stride); + double_int bump = double_int_mul (cand_increment (c), stride); + gimple stmt_to_print = NULL; + slsr_cand_t basis; + tree basis_name, incr_type, bump_tree; + enum tree_code code; + + /* It is highly unlikely, but possible, that the resulting + bump doesn't fit in a HWI. Abandon the replacement + in this case. Restriction to signed HWI is conservative + for unsigned types but allows for safe negation without + twisted logic. */ + if (!double_int_fits_in_shwi_p (bump)) + return; + + basis = lookup_cand (c->basis); + basis_name = gimple_assign_lhs (basis->cand_stmt); + incr_type = TREE_TYPE (gimple_assign_rhs1 (c->cand_stmt)); + code = PLUS_EXPR; + + if (double_int_negative_p (bump)) + { + code = MINUS_EXPR; + bump = double_int_neg (bump); + } + + bump_tree = double_int_to_tree (incr_type, bump); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fputs ("Replacing: ", dump_file); + print_gimple_stmt (dump_file, c->cand_stmt, 0, 0); + } + + if (double_int_zero_p (bump)) + { + tree lhs = gimple_assign_lhs (c->cand_stmt); + gimple copy_stmt = gimple_build_assign (lhs, basis_name); + gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt); + gimple_set_location (copy_stmt, gimple_location (c->cand_stmt)); + gsi_replace (&gsi, copy_stmt, false); + if (dump_file && (dump_flags & TDF_DETAILS)) + stmt_to_print = copy_stmt; + } + else + { + tree rhs1 = gimple_assign_rhs1 (c->cand_stmt); + tree rhs2 = gimple_assign_rhs2 (c->cand_stmt); + if (cand_code != NEGATE_EXPR + && ((operand_equal_p (rhs1, basis_name, 0) + && operand_equal_p (rhs2, bump_tree, 0)) + || (operand_equal_p (rhs1, bump_tree, 0) + && operand_equal_p (rhs2, basis_name, 0)))) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fputs ("(duplicate, not actually replacing)", dump_file); + stmt_to_print = c->cand_stmt; + } + } + else + { + gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt); + gimple_assign_set_rhs_with_ops (&gsi, code, basis_name, bump_tree); + update_stmt (gsi_stmt (gsi)); + if (dump_file && (dump_flags & TDF_DETAILS)) + stmt_to_print = gsi_stmt (gsi); + } + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fputs ("With: ", dump_file); + print_gimple_stmt (dump_file, stmt_to_print, 0, 0); + fputs ("\n", dump_file); + } +} + +/* Replace candidate C, each sibling of candidate C, and each + dependent of candidate C with an add or subtract. Note that we + only operate on CAND_MULTs with known strides, so we will never + generate a POINTER_PLUS_EXPR. Each candidate X = (B + i) * S is + replaced by X = Y + ((i - i') * S), as described in the module + commentary. The folded value ((i - i') * S) is referred to here + as the "bump." */ + +static void +replace_dependents (slsr_cand_t c) +{ + enum tree_code cand_code = gimple_assign_rhs_code (c->cand_stmt); + + /* It is not useful to replace casts, copies, or adds of an SSA name + and a constant. Also skip candidates that have already been + replaced under another interpretation. */ + if (cand_code != MODIFY_EXPR + && cand_code != NOP_EXPR + && c->kind == CAND_MULT + && !cand_already_replaced (c)) + replace_dependent (c, cand_code); + + if (c->sibling) + replace_dependents (lookup_cand (c->sibling)); + + if (c->dependent) + replace_dependents (lookup_cand (c->dependent)); +} + +/* Analyze costs of related candidates in the candidate vector, + and make beneficial replacements. */ + +static void +analyze_candidates_and_replace (void) +{ + unsigned i; + slsr_cand_t c; + + /* Each candidate that has a null basis and a non-null + dependent is the root of a tree of related statements. + Analyze each tree to determine a subset of those + statements that can be replaced with maximum benefit. */ + FOR_EACH_VEC_ELT (slsr_cand_t, cand_vec, i, c) + { + slsr_cand_t first_dep; + + if (c->basis != 0 || c->dependent == 0) + continue; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "\nProcessing dependency tree rooted at %d.\n", + c->cand_num); + + first_dep = lookup_cand (c->dependent); + + /* If the common stride of all related candidates is a + known constant, and none of these has a phi-dependence, + then all replacements are considered profitable. + Each replaces a multiply by a single add, with the + possibility that a feeding add also goes dead as a + result. */ + if (unconditional_cands_with_known_stride_p (c)) + replace_dependents (first_dep); + + /* TODO: When the stride is an SSA name, it may still be + profitable to replace some or all of the dependent + candidates, depending on whether the introduced increments + can be reused, or are less expensive to calculate than + the replaced statements. */ + + /* TODO: Strength-reduce data references with implicit + multiplication in their addressing expressions. */ + + /* TODO: When conditional increments occur so that a + candidate is dependent upon a phi-basis, the cost of + introducing a temporary must be accounted for. */ + } +} + +static unsigned +execute_strength_reduction (void) +{ + struct dom_walk_data walk_data; + + /* Create the obstack where candidates will reside. */ + gcc_obstack_init (&cand_obstack); + + /* Allocate the candidate vector. */ + cand_vec = VEC_alloc (slsr_cand_t, heap, 128); + + /* Allocate the mapping from statements to candidate indices. */ + stmt_cand_map = pointer_map_create (); + + /* Create the obstack where candidate chains will reside. */ + gcc_obstack_init (&chain_obstack); + + /* Allocate the mapping from base names to candidate chains. */ + base_cand_map = XNEWVEC (cand_chain_t, num_ssa_names); + memset (base_cand_map, 0, num_ssa_names * sizeof (cand_chain_t)); + + /* Initialize the loop optimizer. We need to detect flow across + back edges, and this gives us dominator information as well. */ + loop_optimizer_init (AVOID_CFG_MODIFICATIONS); + + /* Initialize costs tables in IVOPTS. */ + initialize_costs (); + + /* Set up callbacks for the generic dominator tree walker. */ + walk_data.dom_direction = CDI_DOMINATORS; + walk_data.initialize_block_local_data = NULL; + walk_data.before_dom_children = find_candidates_in_block; + walk_data.after_dom_children = NULL; + walk_data.global_data = NULL; + walk_data.block_local_data_size = 0; + init_walk_dominator_tree (&walk_data); + + /* Walk the CFG in predominator order looking for strength reduction + candidates. */ + walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + dump_cand_vec (); + dump_cand_chains (); + } + + /* Analyze costs and make appropriate replacements. */ + analyze_candidates_and_replace (); + + /* Free resources. */ + fini_walk_dominator_tree (&walk_data); + loop_optimizer_finalize (); + free (base_cand_map); + obstack_free (&chain_obstack, NULL); + pointer_map_destroy (stmt_cand_map); + VEC_free (slsr_cand_t, heap, cand_vec); + obstack_free (&cand_obstack, NULL); + finalize_costs (); + + return 0; +} + +static bool +gate_strength_reduction (void) +{ + return optimize > 0; +} + +struct gimple_opt_pass pass_strength_reduction = +{ + { + GIMPLE_PASS, + "slsr", /* name */ + gate_strength_reduction, /* gate */ + execute_strength_reduction, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_GIMPLE_SLSR, /* tv_id */ + PROP_cfg | PROP_ssa, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_verify_ssa /* todo_flags_finish */ + } +}; Index: gcc/tree-flow.h =================================================================== --- gcc/tree-flow.h (revision 188891) +++ gcc/tree-flow.h (working copy) @@ -810,6 +810,8 @@ bool expr_invariant_in_loop_p (struct loop *, tree bool stmt_invariant_in_loop_p (struct loop *, gimple); bool multiplier_allowed_in_address_p (HOST_WIDE_INT, enum machine_mode, addr_space_t); +void initialize_costs (void); +void finalize_costs (void); unsigned multiply_by_const_cost (HOST_WIDE_INT, enum machine_mode, bool); unsigned add_regs_cost (enum machine_mode, bool); unsigned multiply_regs_cost (enum machine_mode, bool); Index: gcc/Makefile.in =================================================================== --- gcc/Makefile.in (revision 188890) +++ gcc/Makefile.in (working copy) @@ -1243,6 +1243,7 @@ OBJS = \ gimple-fold.o \ gimple-low.o \ gimple-pretty-print.o \ + gimple-ssa-strength-reduction.o \ gimple-streamer-in.o \ gimple-streamer-out.o \ gimplify.o \ @@ -2432,6 +2433,11 @@ tree-ssa-sccvn.o : tree-ssa-sccvn.c $(TREE_FLOW_H) alloc-pool.h $(BASIC_BLOCK_H) $(BITMAP_H) langhooks.h $(HASHTAB_H) $(GIMPLE_H) \ $(TREE_INLINE_H) tree-iterator.h tree-ssa-propagate.h tree-ssa-sccvn.h \ $(PARAMS_H) $(GIMPLE_PRETTY_PRINT_H) gimple-fold.h +gimple-ssa-strength-reduction.o : gimple-ssa-strength-reduction.c $(CONFIG_H) \ + $(SYSTEM_H) coretypes.h $(TREE_H) $(GIMPLE_H) $(BASIC_BLOCK_H) \ + $(TREE_PASS_H) $(TIMEVAR_H) $(CFGLOOP_H) $(TREE_PRETTY_PRINT_H) \ + $(GIMPLE_PRETTY_PRINT_H) alloc-pool.h $(TREE_FLOW_H) domwalk.h \ + pointer-set.h tree-vrp.o : tree-vrp.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(TREE_H) \ $(TREE_FLOW_H) $(TREE_PASS_H) $(TREE_DUMP_H) $(DIAGNOSTIC_CORE_H) $(GGC_H) \ $(BASIC_BLOCK_H) tree-ssa-propagate.h $(FLAGS_H) $(TREE_DUMP_H) \ Index: gcc/passes.c =================================================================== --- gcc/passes.c (revision 188890) +++ gcc/passes.c (working copy) @@ -1463,6 +1463,7 @@ init_optimization_passes (void) NEXT_PASS (pass_cse_reciprocals); NEXT_PASS (pass_reassoc); NEXT_PASS (pass_vrp); + NEXT_PASS (pass_strength_reduction); NEXT_PASS (pass_dominator); /* The only const/copy propagation opportunities left after DOM should be due to degenerate PHI nodes. So rather than