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convert fptosi(sitofp x) -> x if the fp value has enough bits in its mantissa

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to accurately represent the integer.  This triggers 9 times in 471.omnetpp,
though 8 of those seem to be inlined from the same place.

llvm-svn: 51271
This commit is contained in:
Chris Lattner 2008-05-19 20:25:04 +00:00
parent 1435b94f62
commit 63c384df1e
2 changed files with 35 additions and 9 deletions
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36
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -208,8 +208,8 @@ namespace {
Instruction *visitSExt(SExtInst &CI);
Instruction *visitFPTrunc(FPTruncInst &CI);
Instruction *visitFPExt(CastInst &CI);
Instruction *visitFPToUI(CastInst &CI);
Instruction *visitFPToSI(CastInst &CI);
Instruction *visitFPToUI(FPToUIInst &FI);
Instruction *visitFPToSI(FPToSIInst &FI);
Instruction *visitUIToFP(CastInst &CI);
Instruction *visitSIToFP(CastInst &CI);
Instruction *visitPtrToInt(CastInst &CI);
@ -2439,9 +2439,9 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
} while (Size >= 1);
// FIXME: This shouldn't be necessary. When the backends can handle types
// with funny bit widths then this whole cascade of if statements should
// be removed. It is just here to get the size of the "middle" type back
// up to something that the back ends can handle.
// with funny bit widths then this switch statement should be removed. It
// is just here to get the size of the "middle" type back up to something
// that the back ends can handle.
const Type *MiddleType = 0;
switch (Size) {
default: break;
@ -7995,12 +7995,30 @@ Instruction *InstCombiner::visitFPExt(CastInst &CI) {
return commonCastTransforms(CI);
}
Instruction *InstCombiner::visitFPToUI(CastInst &CI) {
return commonCastTransforms(CI);
Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
// fptoui(uitofp(X)) --> X if the intermediate type has enough bits in its
// mantissa to accurately represent all values of X. For example, do not
// do this with i64->float->i64.
if (UIToFPInst *SrcI = dyn_cast<UIToFPInst>(FI.getOperand(0)))
if (SrcI->getOperand(0)->getType() == FI.getType() &&
(int)FI.getType()->getPrimitiveSizeInBits() < /*extra bit for sign */
GetFPMantissaWidth(SrcI->getType()))
return ReplaceInstUsesWith(FI, SrcI->getOperand(0));
return commonCastTransforms(FI);
}
Instruction *InstCombiner::visitFPToSI(CastInst &CI) {
return commonCastTransforms(CI);
Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
// fptosi(sitofp(X)) --> X if the intermediate type has enough bits in its
// mantissa to accurately represent all values of X. For example, do not
// do this with i64->float->i64.
if (SIToFPInst *SrcI = dyn_cast<SIToFPInst>(FI.getOperand(0)))
if (SrcI->getOperand(0)->getType() == FI.getType() &&
(int)FI.getType()->getPrimitiveSizeInBits() <=
GetFPMantissaWidth(SrcI->getType()))
return ReplaceInstUsesWith(FI, SrcI->getOperand(0));
return commonCastTransforms(FI);
}
Instruction *InstCombiner::visitUIToFP(CastInst &CI) {

8
test/Transforms/InstCombine/sitofp.ll
View File

@ -23,3 +23,11 @@ define i1 @test4(i8 %A) {
ret i1 %C ; A != 127
}
define i32 @test5(i32 %A) {
%B = sitofp i32 %A to double
%C = fptosi double %B to i32
%D = uitofp i32 %C to double
%E = fptoui double %D to i32
ret i32 %E
}