[MIPS GlobalISel] Lower fptoui
Add lower for G_FPTOUI. Algorithm is similar to the SDAG version
in TargetLowering::expandFP_TO_UINT.
Lower G_FPTOUI for MIPS32.
Differential Revision: https://reviews.llvm.org/D66929
llvm-svn: 370431
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 79297d3..c37b115 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -2125,6 +2125,8 @@
return lowerUITOFP(MI, TypeIdx, Ty);
case G_SITOFP:
return lowerSITOFP(MI, TypeIdx, Ty);
+ case G_FPTOUI:
+ return lowerFPTOUI(MI, TypeIdx, Ty);
case G_SMIN:
case G_SMAX:
case G_UMIN:
@@ -3715,6 +3717,48 @@
return UnableToLegalize;
}
+LegalizerHelper::LegalizeResult
+LegalizerHelper::lowerFPTOUI(MachineInstr &MI, unsigned TypeIdx, LLT Ty) {
+ Register Dst = MI.getOperand(0).getReg();
+ Register Src = MI.getOperand(1).getReg();
+ LLT DstTy = MRI.getType(Dst);
+ LLT SrcTy = MRI.getType(Src);
+ const LLT S64 = LLT::scalar(64);
+ const LLT S32 = LLT::scalar(32);
+
+ if (SrcTy != S64 && SrcTy != S32)
+ return UnableToLegalize;
+ if (DstTy != S32 && DstTy != S64)
+ return UnableToLegalize;
+
+ // FPTOSI gives same result as FPTOUI for positive signed integers.
+ // FPTOUI needs to deal with fp values that convert to unsigned integers
+ // greater or equal to 2^31 for float or 2^63 for double. For brevity 2^Exp.
+
+ APInt TwoPExpInt = APInt::getSignMask(DstTy.getSizeInBits());
+ APFloat TwoPExpFP(SrcTy.getSizeInBits() == 32 ? APFloat::IEEEsingle()
+ : APFloat::IEEEdouble(),
+ APInt::getNullValue(SrcTy.getSizeInBits()));
+ TwoPExpFP.convertFromAPInt(TwoPExpInt, false, APFloat::rmNearestTiesToEven);
+
+ MachineInstrBuilder FPTOSI = MIRBuilder.buildFPTOSI(DstTy, Src);
+
+ MachineInstrBuilder Threshold = MIRBuilder.buildFConstant(SrcTy, TwoPExpFP);
+ // For fp Value greater or equal to Threshold(2^Exp), we use FPTOSI on
+ // (Value - 2^Exp) and add 2^Exp by setting highest bit in result to 1.
+ MachineInstrBuilder FSub = MIRBuilder.buildFSub(SrcTy, Src, Threshold);
+ MachineInstrBuilder ResLowBits = MIRBuilder.buildFPTOSI(DstTy, FSub);
+ MachineInstrBuilder ResHighBit = MIRBuilder.buildConstant(DstTy, TwoPExpInt);
+ MachineInstrBuilder Res = MIRBuilder.buildXor(DstTy, ResLowBits, ResHighBit);
+
+ MachineInstrBuilder FCMP =
+ MIRBuilder.buildFCmp(CmpInst::FCMP_ULT, DstTy, Src, Threshold);
+ MIRBuilder.buildSelect(Dst, FCMP, FPTOSI, Res);
+
+ MI.eraseFromParent();
+ return Legalized;
+}
+
static CmpInst::Predicate minMaxToCompare(unsigned Opc) {
switch (Opc) {
case TargetOpcode::G_SMIN:
