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Don't forget to check FlagNW when determining whether an AddRecExpr will wrap

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or not. Patch by Brendon Cahoon!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144173 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2011-11-09 07:11:37 +00:00
parent c6bcf4315c
commit 89d093d5b6
2 changed files with 38 additions and 2 deletions
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5
lib/Analysis/ScalarEvolution.cpp
View File

@ -6228,8 +6228,9 @@ ScalarEvolution::HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
return getCouldNotCompute();
// Check to see if we have a flag which makes analysis easy.
bool NoWrap = isSigned ? AddRec->getNoWrapFlags(SCEV::FlagNSW) :
AddRec->getNoWrapFlags(SCEV::FlagNUW);
bool NoWrap = isSigned ?
AddRec->getNoWrapFlags((SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNW)) :
AddRec->getNoWrapFlags((SCEV::NoWrapFlags)(SCEV::FlagNUW | SCEV::FlagNW));
if (AddRec->isAffine()) {
unsigned BitWidth = getTypeSizeInBits(AddRec->getType());

35
test/Analysis/ScalarEvolution/trip-count12.ll Normal file
View File

@ -0,0 +1,35 @@
; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
; CHECK: Determining loop execution counts for: @test
; CHECK: Loop %for.body: backedge-taken count is ((-2 + %len) /u 2)
; CHECK: Loop %for.body: max backedge-taken count is 1073741823
define zeroext i16 @test(i16* nocapture %p, i32 %len) nounwind readonly {
entry:
%cmp2 = icmp sgt i32 %len, 1
br i1 %cmp2, label %for.body.preheader, label %for.end
for.body.preheader: ; preds = %entry
br label %for.body
for.body: ; preds = %for.body, %for.body.preheader
%p.addr.05 = phi i16* [ %incdec.ptr, %for.body ], [ %p, %for.body.preheader ]
%len.addr.04 = phi i32 [ %sub, %for.body ], [ %len, %for.body.preheader ]
%res.03 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
%incdec.ptr = getelementptr inbounds i16* %p.addr.05, i32 1
%0 = load i16* %p.addr.05, align 2
%conv = zext i16 %0 to i32
%add = add i32 %conv, %res.03
%sub = add nsw i32 %len.addr.04, -2
%cmp = icmp sgt i32 %sub, 1
br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge
for.cond.for.end_crit_edge: ; preds = %for.body
%extract.t = trunc i32 %add to i16
br label %for.end
for.end: ; preds = %for.cond.for.end_crit_edge, %entry
%res.0.lcssa.off0 = phi i16 [ %extract.t, %for.cond.for.end_crit_edge ], [ 0, %entry ]
ret i16 %res.0.lcssa.off0
}