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[Clang] Ensure vector predication loop metadata is always emitted when pragma is specified. 

This patch ensures that vector predication and vectorization width
pragmas work together correctly/as expected. Specifically, this patch
fixes the issue that when vectorization_width > 1, the vector
predication behaviour (this would matter if it has NOT been disabled
explicitly by a pragma) was getting ignored, which was incorrect.

The fix here removes the dependence of vector predication on the
vectorization width. The loop metadata corresponding to clang loop
pragma vectorize_predicate is always emitted, if the pragma is
specified, even if vectorization is disabled by vectorize_width(1)
or vectorize(disable) since the option is also used for interleaving
by the LoopVectorize pass.

Reviewed By: dmgreen, Meinersbur

Differential Revision: https://reviews.llvm.org/D94779
This commit is contained in:
Malhar 2021-02-13 15:57:21 -06:00 committed by Michael Kruse
parent 53187f1eec
commit 74ddacd30d
2 changed files with 59 additions and 7 deletions
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11
clang/lib/CodeGen/CGLoopInfo.cpp
View File

@ -250,12 +250,10 @@ LoopInfo::createLoopVectorizeMetadata(const LoopAttributes &Attrs,
Args.push_back(nullptr);
Args.append(LoopProperties.begin(), LoopProperties.end());
// Setting vectorize.predicate
// Setting vectorize.predicate when it has been specified and vectorization
// has not been disabled.
bool IsVectorPredicateEnabled = false;
if (Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified &&
Attrs.VectorizeEnable != LoopAttributes::Disable &&
Attrs.VectorizeWidth < 1) {
if (Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified) {
IsVectorPredicateEnabled =
(Attrs.VectorizePredicateEnable == LoopAttributes::Enable);
@ -303,7 +301,8 @@ LoopInfo::createLoopVectorizeMetadata(const LoopAttributes &Attrs,
// explicitly requested fixed-width vectorization, i.e.
// vectorize.scalable.enable is false.
if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
IsVectorPredicateEnabled || Attrs.VectorizeWidth > 1 ||
(IsVectorPredicateEnabled && Attrs.VectorizeWidth != 1) ||
Attrs.VectorizeWidth > 1 ||
Attrs.VectorizeScalable == LoopAttributes::Enable ||
(Attrs.VectorizeScalable == LoopAttributes::Disable &&
Attrs.VectorizeWidth != 1)) {

55
clang/test/CodeGenCXX/pragma-loop-predicate.cpp
View File

@ -58,6 +58,49 @@ void test5(int *List, int Length) {
List[i] = i * 2;
}
// Check that vectorize_predicate is ignored when vectorization width is 1
void test6(int *List, int Length) {
// CHECK-LABEL: @{{.*}}test6{{.*}}(
// CHECK: br label {{.*}}, !llvm.loop ![[LOOP6:.*]]
#pragma clang loop vectorize_predicate(disable) vectorize_width(1)
for (int i = 0; i < Length; i++)
List[i] = i * 2;
}
// Check that vectorize_width(!=1) does not affect vectorize_predicate.
void test7(int *List, int Length) {
// CHECK-LABEL: @{{.*}}test7{{.*}}(
// CHECK: br label {{.*}}, !llvm.loop ![[LOOP7:.*]]
#pragma clang loop vectorize_predicate(disable) vectorize_width(4)
for (int i = 0; i < Length; i++)
List[i] = i * 2;
}
// Check that vectorize_predicate is ignored when vectorization width is 1
void test8(int *List, int Length) {
// CHECK-LABEL: @{{.*}}test8{{.*}}(
// CHECK: br label {{.*}}, !llvm.loop ![[LOOP8:.*]]
#pragma clang loop vectorize_predicate(enable) vectorize_width(1)
for (int i = 0; i < Length; i++)
List[i] = i * 2;
}
// Check that vectorize_width(!=1) does not affect vectorize_predicate.
void test9(int *List, int Length) {
// CHECK-LABEL: @{{.*}}test9{{.*}}(
// CHECK: br label {{.*}}, !llvm.loop ![[LOOP9:.*]]
#pragma clang loop vectorize_predicate(enable) vectorize_width(4)
for (int i = 0; i < Length; i++)
List[i] = i * 2;
}
// CHECK: ![[LOOP0]] = distinct !{![[LOOP0]], [[MP:![0-9]+]], [[GEN3:![0-9]+]]}
// CHECK: [[MP]] = !{!"llvm.loop.mustprogress"}
// CHECK-NEXT: [[GEN3]] = !{!"llvm.loop.vectorize.enable", i1 true}
@ -73,4 +116,14 @@ void test5(int *List, int Length) {
// CHECK-NEXT: ![[LOOP4]] = distinct !{![[LOOP4]], [[MP]], [[GEN10:![0-9]+]]}
// CHECK-NEXT: [[GEN10]] = !{!"llvm.loop.vectorize.width", i32 1}
// CHECK-NEXT: ![[LOOP5]] = distinct !{![[LOOP5]], [[MP]], [[GEN10]]}
// CHECK-NEXT: ![[LOOP5]] = distinct !{![[LOOP5]], [[MP]], [[GEN6]], [[GEN10]]}
// CHECK-NEXT: ![[LOOP6]] = distinct !{![[LOOP6]], [[MP]], [[GEN8]], [[GEN10]], [[GEN11:![0-9]+]]}
// CHECK-NEXT: [[GEN11]] = !{!"llvm.loop.vectorize.scalable.enable", i1 false}
// CHECK-NEXT: ![[LOOP7]] = distinct !{![[LOOP7]], [[MP]], [[GEN8]], [[GEN12:![0-9]+]], [[GEN11]], [[GEN3]]}
// CHECK-NEXT: [[GEN12]] = !{!"llvm.loop.vectorize.width", i32 4}
// CHECK-NEXT: ![[LOOP8]] = distinct !{![[LOOP8]], [[MP]], [[GEN6]], [[GEN10]], [[GEN11]]}
// CHECK-NEXT: ![[LOOP9]] = distinct !{![[LOOP9]], [[MP]], [[GEN6]], [[GEN12]], [[GEN11]], [[GEN3]]}