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[LV] PreferPredicateOverEpilog respecting predicate loop hint

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The vectoriser queries TTI->preferPredicateOverEpilogue to determine if
tail-folding is preferred for a loop, but it was not respecting loop hint
'predicate' that can disable this, which has now been added. This showed that
we were incorrectly initialising loop hint 'vectorize.predicate.enable' with 0
(i.e. FK_Disabled) but this should have been FK_Undefined, which has been
fixed.

Differential Revision: https://reviews.llvm.org/D70125
This commit is contained in:
Sjoerd Meijer
2019-11-14 13:10:44 +00:00
parent 1c247dd028
commit cb47b87830
3 changed files with 11 additions and 12 deletions
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2
llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
View File

@@ -72,7 +72,7 @@ LoopVectorizeHints::LoopVectorizeHints(const Loop *L,
Interleave("interleave.count", InterleaveOnlyWhenForced, HK_UNROLL),
Force("vectorize.enable", FK_Undefined, HK_FORCE),
IsVectorized("isvectorized", 0, HK_ISVECTORIZED),
Predicate("vectorize.predicate.enable", 0, HK_PREDICATE), TheLoop(L),
Predicate("vectorize.predicate.enable", FK_Undefined, HK_PREDICATE), TheLoop(L),
ORE(ORE) {
// Populate values with existing loop metadata.
getHintsFromMetadata();

6
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@@ -7433,8 +7433,10 @@ getScalarEpilogueLowering(Function *F, Loop *L, LoopVectorizeHints &Hints,
(F->hasOptSize() ||
llvm::shouldOptimizeForSize(L->getHeader(), PSI, BFI)))
SEL = CM_ScalarEpilogueNotAllowedOptSize;
else if (PreferPredicateOverEpilog || Hints.getPredicate() ||
TTI->preferPredicateOverEpilogue(L, LI, *SE, *AC, TLI, DT, LAI))
else if (PreferPredicateOverEpilog ||
Hints.getPredicate() == LoopVectorizeHints::FK_Enabled ||
(TTI->preferPredicateOverEpilogue(L, LI, *SE, *AC, TLI, DT, LAI) &&
Hints.getPredicate() != LoopVectorizeHints::FK_Disabled))
SEL = CM_ScalarEpilogueNotNeededUsePredicate;
return SEL;

15
llvm/test/Transforms/LoopVectorize/ARM/prefer-tail-loop-folding.ll
View File

@@ -323,15 +323,12 @@ for.end:
}
define void @pragma_vect_predicate_disable(i32* noalias nocapture %A, i32* noalias nocapture readonly %B, i32* noalias nocapture readonly %C) #0 {
; CHECK-LABEL: pragma_vect_predicate_disable(
;
; FIXME:
; respect loop hint predicate.enable = false, and don't tail-fold here:
;
; PREFER-FOLDING: call <4 x i32> @llvm.masked.load.v4i32.p0v4i32
; PREFER-FOLDING: call <4 x i32> @llvm.masked.load.v4i32.p0v4i32
; PREFER-FOLDING: call void @llvm.masked.store.v4i32.p0v4i32
; PREFER-FOLDING: br i1 %{{.*}}, label %{{.*}}, label %vector.body
; CHECK-LABEL: pragma_vect_predicate_disable(
; PREFER-FOLDING: vector.body:
; PREFER-FOLDING-NOT: call <4 x i32> @llvm.masked.load.v4i32.p0v4i32
; PREFER-FOLDING-NOT: call <4 x i32> @llvm.masked.load.v4i32.p0v4i32
; PREFER-FOLDING-NOT: call void @llvm.masked.store.v4i32.p0v4i32
; PREFER-FOLDING: br i1 %{{.*}}, label %{{.*}}, label %vector.body
entry:
br label %for.body