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Fix bug in FoldFCmp_IntToFP_Cst. If inttofp is a uintofp, use unsigned instead of signed integer constant. 

llvm-svn: 72300
This commit is contained in:
Evan Cheng 2009-05-22 23:10:53 +00:00
parent 36fe6901d4
commit a838a40bc4
2 changed files with 76 additions and 61 deletions
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18
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -5598,12 +5598,17 @@ Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
// [0, UMAX], but it may still be fractional. See if it is fractional by
// casting the FP value to the integer value and back, checking for equality.
// Don't do this for zero, because -0.0 is not fractional.
Constant *RHSInt = ConstantExpr::getFPToSI(RHSC, IntTy);
if (!RHS.isZero() &&
ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) != RHSC) {
// If we had a comparison against a fractional value, we have to adjust the
// compare predicate and sometimes the value. RHSC is rounded towards zero
// at this point.
Constant *RHSInt = LHSUnsigned
? ConstantExpr::getFPToUI(RHSC, IntTy)
: ConstantExpr::getFPToSI(RHSC, IntTy);
if (!RHS.isZero()) {
bool Equal = LHSUnsigned
? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
: ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
if (!Equal) {
// If we had a comparison against a fractional value, we have to adjust
// the compare predicate and sometimes the value. RHSC is rounded towards
// zero at this point.
switch (Pred) {
default: assert(0 && "Unexpected integer comparison!");
case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
@ -5662,6 +5667,7 @@ Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
break;
}
}
}
// Lower this FP comparison into an appropriate integer version of the
// comparison.

9
llvm/test/Transforms/InstCombine/2009-05-23-FCmpToICmp.ll Normal file
View File

@ -0,0 +1,9 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep cmp
; rdar://6903175
define i1 @f0(i32 *%a) nounwind {
%b = load i32* %a, align 4
%c = uitofp i32 %b to double
%d = fcmp ogt double %c, 0x41EFFFFFFFE00000
ret i1 %d
}