diff mbox series

Fail vectorization when not using SLP and --param vect-force-slp == 1

Message ID 20240918130452.3EFC613508@imap1.dmz-prg2.suse.org
State New
Headers show
Series Fail vectorization when not using SLP and --param vect-force-slp == 1 | expand

Commit Message

Richard Biener Sept. 18, 2024, 1:04 p.m. UTC 
The following adds --param vect-force-slp to enable the transition
to full SLP.  Full SLP is enforced during stmt analysis where it
detects failed SLP discovery and at loop analysis time where it
avoids analyzing a loop with SLP disabled.  Failure to SLP results
in vectorization to fail.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress;  I'll
push after that finishes.

This gives you the ability to dial ahead in time and evaluate
your target as to what happens when we pull the trigger.

Richard.

	* params.def (vect-force-slp): New param, default 0.
	* doc/invoke.texi (--param vect-force-slp): Document.
	* tree-vect-loop.cc (vect_analyze_loop_2): When analyzing
	without SLP but --param vect-force-slp is 1 fail.
	* tree-vect-stmts.cc (vect_analyze_stmt): Fail vectorization
	for non-SLP stmts when --param vect-force-slp is 1.
---
 gcc/doc/invoke.texi    | 3 +++
 gcc/params.opt         | 4 ++++
 gcc/tree-vect-loop.cc  | 6 ++++++
 gcc/tree-vect-stmts.cc | 6 ++++++
 4 files changed, 19 insertions(+)
diff mbox series

Patch

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 511b8c8d311..b91fb9c9cca 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -16955,6 +16955,9 @@  this parameter.  The default value of this parameter is 50.
 @item vect-induction-float
 Enable loop vectorization of floating point inductions.
 
+@item vect-force-slp
+Force the use of SLP when vectorizing, fail if not possible.
+
 @item vrp-block-limit
 Maximum number of basic blocks before VRP switches to a lower memory algorithm.
 
diff --git a/gcc/params.opt b/gcc/params.opt
index c17ba17b91b..949b4754498 100644
--- a/gcc/params.opt
+++ b/gcc/params.opt
@@ -1198,6 +1198,10 @@  The maximum factor which the loop vectorizer applies to the cost of statements i
 Common Joined UInteger Var(param_vect_induction_float) Init(1) IntegerRange(0, 1) Param Optimization
 Enable loop vectorization of floating point inductions.
 
+-param=vect-force-slp=
+Common Joined UInteger Var(param_vect_force_slp) Init(0) IntegerRange(0, 1) Param Optimization
+Force the use of SLP when vectorizing, fail if not possible.
+
 -param=vrp-block-limit=
 Common Joined UInteger Var(param_vrp_block_limit) Init(150000) Optimization Param
 Maximum number of basic blocks before VRP switches to a fast model with less memory requirements.
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 62c7f90779f..d42694d1974 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -2891,6 +2891,12 @@  vect_analyze_loop_2 (loop_vec_info loop_vinfo, bool &fatal,
   /* This is the point where we can re-start analysis with SLP forced off.  */
 start_over:
 
+  /* When we arrive here with SLP disabled and we are supposed
+     to use SLP for everything fail vectorization.  */
+  if (!slp && param_vect_force_slp)
+    return opt_result::failure_at (vect_location,
+				   "may need non-SLP handling\n");
+
   /* Apply the suggested unrolling factor, this was determined by the backend
      during finish_cost the first time we ran the analyzis for this
      vector mode.  */
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index b1353c91fce..495f45e40e6 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -13353,6 +13353,12 @@  vect_analyze_stmt (vec_info *vinfo,
       return opt_result::success ();
     }
 
+  /* When we arrive here with a non-SLP statement and we are supposed
+     to use SLP for everything fail vectorization.  */
+  if (!node && param_vect_force_slp)
+    return opt_result::failure_at (stmt_info->stmt,
+				   "needs non-SLP handling\n");
+
   ok = true;
   if (!bb_vinfo
       && (STMT_VINFO_RELEVANT_P (stmt_info)