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[LoopVectorizer] Fix bailing-out condition for OptForSize case. 

With option OptForSize enabled, the Loop Vectorizer is not supposed to
create tail loop. The condition checking that was invalid and was not
matching to the comment above.

Patch by Marianne Mailhot-Sarrasin.

llvm-svn: 240556
This commit is contained in:
Michael Zolotukhin 2015-06-24 17:26:24 +00:00
parent 8454044b1f
commit 79ff564ef3
2 changed files with 37 additions and 4 deletions
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3
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -4642,10 +4642,9 @@ LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize) {
if (VF == 0)
VF = MaxVectorSize;
else {
// If the trip count that we found modulo the vectorization factor is not
// zero then we require a tail.
if (VF < 2) {
emitAnalysis(VectorizationReport() <<
"cannot optimize for size and vectorize at the "
"same time. Enable vectorization of this loop "

34
llvm/test/Transforms/LoopVectorize/optsize.ll Normal file
View File

@ -0,0 +1,34 @@
; This test verifies that the loop vectorizer will NOT produce a tail
; loop with Optimize for size attibute.
; REQUIRES: asserts
; RUN: opt < %s -loop-vectorize -Os -debug -debug-only=loop-vectorize -S 2>&1 | FileCheck %s
;CHECK-NOT: <2 x i8>
;CHECK-NOT: <4 x i8>
;CHECK: Aborting. A tail loop is required in Os.
target datalayout = "E-m:e-p:32:32-i64:32-f64:32:64-a:0:32-n32-S128"
@tab = common global [32 x i8] zeroinitializer, align 1
; Function Attrs: nounwind optsize
define i32 @foo() #0 {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%i.08 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
%arrayidx = getelementptr inbounds [32 x i8], [32 x i8]* @tab, i32 0, i32 %i.08
%0 = load i8, i8* %arrayidx, align 1
%cmp1 = icmp eq i8 %0, 0
%. = select i1 %cmp1, i8 2, i8 1
store i8 %., i8* %arrayidx, align 1
%inc = add nsw i32 %i.08, 1
%exitcond = icmp eq i32 %i.08, 202
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret i32 0
}
attributes #0 = { nounwind optsize "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }