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Teach indvars to generate nsw/nuw flags when widening an induction variable.

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Fixes PR16600.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186272 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2013-07-14 02:50:07 +00:00
parent 181a289256
commit 409443b1c6
2 changed files with 35 additions and 1 deletions
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7
lib/Analysis/ScalarEvolutionExpander.cpp
View File

@ -1137,7 +1137,12 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
IVIncInsertPos : Pred->getTerminator();
Builder.SetInsertPoint(InsertPos);
Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
if (isa<OverflowingBinaryOperator>(IncV)) {
if (Normalized->getNoWrapFlags(SCEV::FlagNUW))
cast<BinaryOperator>(IncV)->setHasNoUnsignedWrap();
if (Normalized->getNoWrapFlags(SCEV::FlagNSW))
cast<BinaryOperator>(IncV)->setHasNoSignedWrap();
}
PN->addIncoming(IncV, Pred);
}

29
test/Transforms/IndVarSimplify/widen-nsw.ll Normal file
View File

@ -0,0 +1,29 @@
; RUN: opt < %s -indvars -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx"
; CHECK-LABEL: @test1
; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
define i32 @test1(i32* %a) #0 {
entry:
br label %for.cond
for.cond: ; preds = %for.body, %entry
%sum.0 = phi i32 [ 0, %entry ], [ %add, %for.body ]
%i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
%cmp = icmp slt i32 %i.0, 1000
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%idxprom = sext i32 %i.0 to i64
%arrayidx = getelementptr inbounds i32* %a, i64 %idxprom
%0 = load i32* %arrayidx, align 4
%add = add nsw i32 %sum.0, %0
%inc = add nsw i32 %i.0, 1
br label %for.cond
for.end: ; preds = %for.cond
ret i32 %sum.0
}
attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }