From patchwork Thu Nov 1 19:52:44 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dodji Seketeli X-Patchwork-Id: 196361 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 570712C0172 for ; Fri, 2 Nov 2012 06:54:10 +1100 (EST) Comment: DKIM? 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Tested by running cc1 -fasan on the test program below with and without the patch and by inspecting the gimple output to see that there is no change. void foo () { char foo[1] = {0}; foo[0] = 1; } gcc/ * asan.c (create_cond_insert_point_before_iter): Factorize out of ... (build_check_stmt): ... here. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/asan@192844 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/ChangeLog.asan | 3 ++ gcc/asan.c | 120 +++++++++++++++++++++++++++++++++-------------------- 2 files changed, 79 insertions(+), 44 deletions(-) diff --git a/gcc/ChangeLog.asan b/gcc/ChangeLog.asan index 9159b3f..0e0b9b8 100644 --- a/gcc/ChangeLog.asan +++ b/gcc/ChangeLog.asan @@ -1,5 +1,8 @@ 2012-10-26 Dodji Seketeli + * asan.c (create_cond_insert_point_before_iter): Factorize out of ... + (build_check_stmt): ... here. + * asan.c (build_check_stmt): Accept the memory access to be represented by an SSA_NAME. diff --git a/gcc/asan.c b/gcc/asan.c index b43f03b..736286e 100644 --- a/gcc/asan.c +++ b/gcc/asan.c @@ -397,6 +397,75 @@ asan_init_func (void) #define PROB_VERY_UNLIKELY (REG_BR_PROB_BASE / 2000 - 1) #define PROB_ALWAYS (REG_BR_PROB_BASE) +/* Split the current basic block and create a condition statement + insertion point right before the statement pointed to by ITER. + Return an iterator to the point at which the caller might safely + insert the condition statement. + + THEN_BLOCK must be set to the address of an uninitialized instance + of basic_block. The function will then set *THEN_BLOCK to the + 'then block' of the condition statement to be inserted by the + caller. + + Similarly, the function will set *FALLTRHOUGH_BLOCK to the 'else + block' of the condition statement to be inserted by the caller. + + Note that *FALLTHROUGH_BLOCK is a new block that contains the + statements starting from *ITER, and *THEN_BLOCK is a new empty + block. + + *ITER is adjusted to still point to the same statement it was + *pointing to initially. */ + +static gimple_stmt_iterator +create_cond_insert_point_before_iter (gimple_stmt_iterator *iter, + bool then_more_likely_p, + basic_block *then_block, + basic_block *fallthrough_block) +{ + gimple_stmt_iterator gsi = *iter; + + if (!gsi_end_p (gsi)) + gsi_prev (&gsi); + + basic_block cur_bb = gsi_bb (*iter); + + edge e = split_block (cur_bb, gsi_stmt (gsi)); + + /* Get a hold on the 'condition block', the 'then block' and the + 'else block'. */ + basic_block cond_bb = e->src; + basic_block fallthru_bb = e->dest; + basic_block then_bb = create_empty_bb (cond_bb); + + /* Set up the newly created 'then block'. */ + e = make_edge (cond_bb, then_bb, EDGE_TRUE_VALUE); + int fallthrough_probability = + then_more_likely_p + ? PROB_VERY_UNLIKELY + : PROB_ALWAYS - PROB_VERY_UNLIKELY; + e->probability = PROB_ALWAYS - fallthrough_probability; + make_single_succ_edge (then_bb, fallthru_bb, EDGE_FALLTHRU); + + /* Set up the fallthrough basic block. */ + e = find_edge (cond_bb, fallthru_bb); + e->flags = EDGE_FALSE_VALUE; + e->count = cond_bb->count; + e->probability = fallthrough_probability; + + /* Update dominance info for the newly created then_bb; note that + fallthru_bb's dominance info has already been updated by + split_bock. */ + if (dom_info_available_p (CDI_DOMINATORS)) + set_immediate_dominator (CDI_DOMINATORS, then_bb, cond_bb); + + *then_block = then_bb; + *fallthrough_block = fallthru_bb; + *iter = gsi_start_bb (fallthru_bb); + + return gsi_last_bb (cond_bb); +} + /* Instrument the memory access instruction BASE. Insert new statements before ITER. @@ -411,8 +480,7 @@ build_check_stmt (tree base, gimple_stmt_iterator *iter, int size_in_bytes) { gimple_stmt_iterator gsi; - basic_block cond_bb, then_bb, else_bb; - edge e; + basic_block then_bb, else_bb; tree t, base_addr, shadow; gimple g; tree shadow_ptr_type = shadow_ptr_types[size_in_bytes == 16 ? 1 : 0]; @@ -421,51 +489,15 @@ build_check_stmt (tree base, gimple_stmt_iterator *iter, = build_nonstandard_integer_type (TYPE_PRECISION (TREE_TYPE (base)), 1); tree base_ssa = base; - /* We first need to split the current basic block, and start altering - the CFG. This allows us to insert the statements we're about to - construct into the right basic blocks. */ - - cond_bb = gimple_bb (gsi_stmt (*iter)); - gsi = *iter; - gsi_prev (&gsi); - if (!gsi_end_p (gsi)) - e = split_block (cond_bb, gsi_stmt (gsi)); - else - e = split_block_after_labels (cond_bb); - cond_bb = e->src; - else_bb = e->dest; - - /* A recap at this point: else_bb is the basic block at whose head - is the gimple statement for which this check expression is being - built. cond_bb is the (possibly new, synthetic) basic block the - end of which will contain the cache-lookup code, and a - conditional that jumps to the cache-miss code or, much more - likely, over to else_bb. */ - - /* Create the bb that contains the crash block. */ - then_bb = create_empty_bb (cond_bb); - e = make_edge (cond_bb, then_bb, EDGE_TRUE_VALUE); - e->probability = PROB_VERY_UNLIKELY; - make_single_succ_edge (then_bb, else_bb, EDGE_FALLTHRU); - - /* Mark the pseudo-fallthrough edge from cond_bb to else_bb. */ - e = find_edge (cond_bb, else_bb); - e->flags = EDGE_FALSE_VALUE; - e->count = cond_bb->count; - e->probability = PROB_ALWAYS - PROB_VERY_UNLIKELY; - - /* Update dominance info. Note that bb_join's data was - updated by split_block. */ - if (dom_info_available_p (CDI_DOMINATORS)) - { - set_immediate_dominator (CDI_DOMINATORS, then_bb, cond_bb); - set_immediate_dominator (CDI_DOMINATORS, else_bb, cond_bb); - } + /* Get an iterator on the point where we can add the condition + statement for the instrumentation. */ + gsi = create_cond_insert_point_before_iter (iter, + /*then_more_likely_p=*/false, + &then_bb, + &else_bb); base = unshare_expr (base); - gsi = gsi_last_bb (cond_bb); - /* BASE can already be an SSA_NAME; in that case, do not create a new SSA_NAME for it. */ if (TREE_CODE (base) != SSA_NAME)