[gcc r15-1391] Enhance if-conversion for automatic arrays
Richard Biener
rguenth@gcc.gnu.org
Tue Jun 18 05:46:44 GMT 2024
https://gcc.gnu.org/g:4b75ed33fa5fd604897e7a30e79bd28d46598373
commit r15-1391-g4b75ed33fa5fd604897e7a30e79bd28d46598373
Author: Richard Biener <rguenther@suse.de>
Date: Fri Jun 14 14:46:08 2024 +0200
Enhance if-conversion for automatic arrays
Automatic arrays that are not address-taken should not be subject to
store data races. This applies to OMP SIMD in-branch lowered
functions result array which for the testcase otherwise prevents
vectorization with SSE and for AVX and AVX512 ends up with spurious
.MASK_STORE to the stack surviving.
This inefficiency was noted in PR111793.
I've introduced ref_can_have_store_data_races, commonizing uses
of flag_store_data_races in if-conversion, cselim and store motion.
PR tree-optimization/111793
* tree-ssa-alias.h (ref_can_have_store_data_races): Declare.
* tree-ssa-alias.cc (ref_can_have_store_data_races): New
function.
* tree-if-conv.cc (ifcvt_memrefs_wont_trap): Use
ref_can_have_store_data_races to allow more unconditional
stores.
* tree-ssa-loop-im.cc (execute_sm): Likewise.
* tree-ssa-phiopt.cc (cond_store_replacement): Likewise.
* gcc.dg/vect/vect-simd-clone-21.c: New testcase.
Diff:
---
gcc/testsuite/gcc.dg/vect/vect-simd-clone-21.c | 16 ++++++++++++++++
gcc/tree-if-conv.cc | 11 +++++------
gcc/tree-ssa-alias.cc | 19 +++++++++++++++++++
gcc/tree-ssa-alias.h | 2 ++
gcc/tree-ssa-loop-im.cc | 2 +-
gcc/tree-ssa-phiopt.cc | 4 +---
6 files changed, 44 insertions(+), 10 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/vect/vect-simd-clone-21.c b/gcc/testsuite/gcc.dg/vect/vect-simd-clone-21.c
new file mode 100644
index 000000000000..49c52fb59bd1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-simd-clone-21.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_simd_clones } */
+/* { dg-additional-options "-fopenmp-simd" } */
+
+#pragma omp declare simd simdlen(4) inbranch
+__attribute__((noinline)) int
+foo (int a, int b)
+{
+ return a + b;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 4 "vect" { target i?86-*-* x86_64-*-* } } } */
+/* if-conversion shouldn't need to resort to masked stores for the result
+ array created by OMP lowering since that's automatic and does not have
+ its address taken. */
+/* { dg-final { scan-tree-dump-not "MASK_STORE" "vect" } } */
diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index c4c3ed41a447..57992b6decaf 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -936,12 +936,11 @@ ifcvt_memrefs_wont_trap (gimple *stmt, vec<data_reference_p> drs)
/* an unconditionaly write won't trap if the base is written
to unconditionally. */
- if (base_master_dr
- && DR_BASE_W_UNCONDITIONALLY (*base_master_dr))
- return flag_store_data_races;
- /* or the base is known to be not readonly. */
- else if (base_object_writable (DR_REF (a)))
- return flag_store_data_races;
+ if ((base_master_dr
+ && DR_BASE_W_UNCONDITIONALLY (*base_master_dr))
+ /* or the base is known to be not readonly. */
+ || base_object_writable (DR_REF (a)))
+ return !ref_can_have_store_data_races (base);
}
return false;
diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc
index 1a91d63a31ec..fab048b0b594 100644
--- a/gcc/tree-ssa-alias.cc
+++ b/gcc/tree-ssa-alias.cc
@@ -3704,6 +3704,25 @@ stmt_kills_ref_p (gimple *stmt, tree ref)
return stmt_kills_ref_p (stmt, &r);
}
+/* Return whether REF can be subject to store data races. */
+
+bool
+ref_can_have_store_data_races (tree ref)
+{
+ /* With -fallow-store-data-races do not care about them. */
+ if (flag_store_data_races)
+ return false;
+
+ tree base = get_base_address (ref);
+ if (auto_var_p (base)
+ && ! may_be_aliased (base))
+ /* Automatic variables not aliased are not subject to
+ data races. */
+ return false;
+
+ return true;
+}
+
/* Walk the virtual use-def chain of VUSE until hitting the virtual operand
TARGET or a statement clobbering the memory reference REF in which
diff --git a/gcc/tree-ssa-alias.h b/gcc/tree-ssa-alias.h
index 5cd64e722955..5834533ae9cd 100644
--- a/gcc/tree-ssa-alias.h
+++ b/gcc/tree-ssa-alias.h
@@ -144,6 +144,8 @@ extern bool call_may_clobber_ref_p (gcall *, tree, bool = true);
extern bool call_may_clobber_ref_p_1 (gcall *, ao_ref *, bool = true);
extern bool stmt_kills_ref_p (gimple *, tree);
extern bool stmt_kills_ref_p (gimple *, ao_ref *);
+extern bool ref_can_have_store_data_races (tree);
+
enum translate_flags
{ TR_TRANSLATE, TR_VALUEIZE_AND_DISAMBIGUATE, TR_DISAMBIGUATE };
extern tree get_continuation_for_phi (gimple *, ao_ref *, bool,
diff --git a/gcc/tree-ssa-loop-im.cc b/gcc/tree-ssa-loop-im.cc
index f3fda2bd7ce1..3acbd886a0da 100644
--- a/gcc/tree-ssa-loop-im.cc
+++ b/gcc/tree-ssa-loop-im.cc
@@ -2298,7 +2298,7 @@ execute_sm (class loop *loop, im_mem_ref *ref,
bool always_stored = ref_always_accessed_p (loop, ref, true);
if (maybe_mt
&& (bb_in_transaction (loop_preheader_edge (loop)->src)
- || (! flag_store_data_races && ! always_stored)))
+ || (ref_can_have_store_data_races (ref->mem.ref) && ! always_stored)))
multi_threaded_model_p = true;
if (multi_threaded_model_p && !use_other_flag_var)
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 0ef42a1031a2..f05ca727503b 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -3343,9 +3343,7 @@ cond_store_replacement (basic_block middle_bb, basic_block join_bb,
/* If LHS is an access to a local variable without address-taken
(or when we allow data races) and known not to trap, we could
always safely move down the store. */
- tree base = get_base_address (lhs);
- if (!auto_var_p (base)
- || (TREE_ADDRESSABLE (base) && !flag_store_data_races)
+ if (ref_can_have_store_data_races (lhs)
|| tree_could_trap_p (lhs))
return false;
}
More information about the Gcc-cvs
mailing list