[FPEnv] Generate constrained FP comparisons from clang
Update the IRBuilder to generate constrained FP comparisons in
CreateFCmp when IsFPConstrained is true, similar to the other
places in the IRBuilder.
Also, add a new CreateFCmpS to emit signaling FP comparisons,
and use it in clang where comparisons are supposed to be signaling
(currently, only when emitting code for the <, <=, >, >= operators).
Note that there is currently no way to add fast-math flags to a
constrained FP comparison, since this is implemented as an intrinsic
call that returns a boolean type, and FMF are only allowed for calls
returning a floating-point type. However, given the discussion around
https://bugs.llvm.org/show_bug.cgi?id=42179, it seems that FCmp itself
really shouldn't have any FMF either, so this is probably OK.
Reviewed by: craig.topper
Differential Revision: https://reviews.llvm.org/D71467
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 4adaca8..4338d1c 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -798,17 +798,17 @@
// Comparisons.
Value *EmitCompare(const BinaryOperator *E, llvm::CmpInst::Predicate UICmpOpc,
llvm::CmpInst::Predicate SICmpOpc,
- llvm::CmpInst::Predicate FCmpOpc);
-#define VISITCOMP(CODE, UI, SI, FP) \
+ llvm::CmpInst::Predicate FCmpOpc, bool IsSignaling);
+#define VISITCOMP(CODE, UI, SI, FP, SIG) \
Value *VisitBin##CODE(const BinaryOperator *E) { \
return EmitCompare(E, llvm::ICmpInst::UI, llvm::ICmpInst::SI, \
- llvm::FCmpInst::FP); }
- VISITCOMP(LT, ICMP_ULT, ICMP_SLT, FCMP_OLT)
- VISITCOMP(GT, ICMP_UGT, ICMP_SGT, FCMP_OGT)
- VISITCOMP(LE, ICMP_ULE, ICMP_SLE, FCMP_OLE)
- VISITCOMP(GE, ICMP_UGE, ICMP_SGE, FCMP_OGE)
- VISITCOMP(EQ, ICMP_EQ , ICMP_EQ , FCMP_OEQ)
- VISITCOMP(NE, ICMP_NE , ICMP_NE , FCMP_UNE)
+ llvm::FCmpInst::FP, SIG); }
+ VISITCOMP(LT, ICMP_ULT, ICMP_SLT, FCMP_OLT, true)
+ VISITCOMP(GT, ICMP_UGT, ICMP_SGT, FCMP_OGT, true)
+ VISITCOMP(LE, ICMP_ULE, ICMP_SLE, FCMP_OLE, true)
+ VISITCOMP(GE, ICMP_UGE, ICMP_SGE, FCMP_OGE, true)
+ VISITCOMP(EQ, ICMP_EQ , ICMP_EQ , FCMP_OEQ, false)
+ VISITCOMP(NE, ICMP_NE , ICMP_NE , FCMP_UNE, false)
#undef VISITCOMP
Value *VisitBinAssign (const BinaryOperator *E);
@@ -3804,7 +3804,8 @@
Value *ScalarExprEmitter::EmitCompare(const BinaryOperator *E,
llvm::CmpInst::Predicate UICmpOpc,
llvm::CmpInst::Predicate SICmpOpc,
- llvm::CmpInst::Predicate FCmpOpc) {
+ llvm::CmpInst::Predicate FCmpOpc,
+ bool IsSignaling) {
TestAndClearIgnoreResultAssign();
Value *Result;
QualType LHSTy = E->getLHS()->getType();
@@ -3900,7 +3901,10 @@
if (BOInfo.isFixedPointBinOp()) {
Result = EmitFixedPointBinOp(BOInfo);
} else if (LHS->getType()->isFPOrFPVectorTy()) {
- Result = Builder.CreateFCmp(FCmpOpc, LHS, RHS, "cmp");
+ if (!IsSignaling)
+ Result = Builder.CreateFCmp(FCmpOpc, LHS, RHS, "cmp");
+ else
+ Result = Builder.CreateFCmpS(FCmpOpc, LHS, RHS, "cmp");
} else if (LHSTy->hasSignedIntegerRepresentation()) {
Result = Builder.CreateICmp(SICmpOpc, LHS, RHS, "cmp");
} else {
@@ -3957,6 +3961,8 @@
Value *ResultR, *ResultI;
if (CETy->isRealFloatingType()) {
+ // As complex comparisons can only be equality comparisons, they
+ // are never signaling comparisons.
ResultR = Builder.CreateFCmp(FCmpOpc, LHS.first, RHS.first, "cmp.r");
ResultI = Builder.CreateFCmp(FCmpOpc, LHS.second, RHS.second, "cmp.i");
} else {