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LSR must sometimes sign-extend before generating double constants.

Browse Source 
rdar://9786536


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135650 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2011-07-21 01:05:01 +00:00
parent fb4eb165d6
commit c2c988e5e0
2 changed files with 30 additions and 4 deletions
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13
lib/Transforms/Scalar/LoopStrengthReduce.cpp
View File

@ -1427,6 +1427,7 @@ void LSRInstance::OptimizeShadowIV() {
++UI;
Instruction *ShadowUse = CandidateUI->getUser();
Type *DestTy = NULL;
bool IsSigned = false;
/* If shadow use is a int->float cast then insert a second IV
to eliminate this cast.
@ -1440,10 +1441,14 @@ void LSRInstance::OptimizeShadowIV() {
for (unsigned i = 0; i < n; ++i, ++d)
foo(d);
*/
if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser()))
if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser())) {
IsSigned = false;
DestTy = UCast->getDestTy();
else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser()))
}
else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser())) {
IsSigned = true;
DestTy = SCast->getDestTy();
}
if (!DestTy) continue;
if (TLI) {
@ -1474,7 +1479,9 @@ void LSRInstance::OptimizeShadowIV() {
ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));
if (!Init) continue;
Constant *NewInit = ConstantFP::get(DestTy, Init->getZExtValue());
Constant *NewInit = ConstantFP::get(DestTy, IsSigned ?
Init->getSExtValue() :
Init->getZExtValue());
BinaryOperator *Incr =
dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));

21
test/Transforms/LoopStrengthReduce/2011-07-20-DoubleIV.ll
View File

@ -15,7 +15,26 @@ entry:
loop:
%i.01 = phi i32 [ -39, %entry ], [ %inc, %loop ]
%conv7 = sitofp i32 %i.01 to double
%conv = sitofp i32 %i.01 to double
%inc = add nsw i32 %i.01, 1
br i1 undef, label %loop, label %for.end
for.end:
unreachable
}
; Now check that the computed double constant is correct.
; CHECK: @doubleIV
; CHECK: phi double [ 0x43F0000000000000, %entry ]
; CHECK: br
define void @doubleIV() nounwind {
entry:
br label %loop
loop:
%i.01 = phi i32 [ -39, %entry ], [ %inc, %loop ]
%conv = sitofp i32 %i.01 to double
%div = fdiv double %conv, 4.000000e+01
%inc = add nsw i32 %i.01, 1
br i1 undef, label %loop, label %for.end