Set the LLVM FP optimization flags conservatively.
Functions can have local pragmas that override the global settings.
We set the flags eagerly based on global settings, but if we emit
an expression under the influence of a pragma, we clear the
appropriate flags from the function.
In order to avoid doing a ton of redundant work whenever we emit
an FP expression, configure the IRBuilder to default to global
settings, and only reconfigure it when we see an FP expression
that's not using the global settings.
Patch by Michele Scandale!
https://reviews.llvm.org/D80462
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index b2bc38b..83614b0 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -215,23 +215,6 @@
(2 * Ctx.getTypeSize(RHSTy)) < PromotedSize;
}
-static void setBuilderFlagsFromFPFeatures(CGBuilderTy &Builder,
- CodeGenFunction &CGF,
- FPOptions FPFeatures) {
- auto NewRoundingBehavior = FPFeatures.getRoundingMode();
- Builder.setDefaultConstrainedRounding(NewRoundingBehavior);
- auto NewExceptionBehavior =
- ToConstrainedExceptMD(FPFeatures.getExceptionMode());
- Builder.setDefaultConstrainedExcept(NewExceptionBehavior);
- CGF.SetFastMathFlags(FPFeatures);
- assert((CGF.CurFuncDecl == nullptr || Builder.getIsFPConstrained() ||
- isa<CXXConstructorDecl>(CGF.CurFuncDecl) ||
- isa<CXXDestructorDecl>(CGF.CurFuncDecl) ||
- (NewExceptionBehavior == llvm::fp::ebIgnore &&
- NewRoundingBehavior == llvm::RoundingMode::NearestTiesToEven)) &&
- "FPConstrained should be enabled on entire function");
-}
-
class ScalarExprEmitter
: public StmtVisitor<ScalarExprEmitter, Value*> {
CodeGenFunction &CGF;
@@ -764,8 +747,7 @@
if (Ops.LHS->getType()->isFPOrFPVectorTy()) {
// Preserve the old values
- llvm::IRBuilder<>::FastMathFlagGuard FMFG(Builder);
- setBuilderFlagsFromFPFeatures(Builder, CGF, Ops.FPFeatures);
+ CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, Ops.FPFeatures);
return Builder.CreateFMul(Ops.LHS, Ops.RHS, "mul");
}
if (Ops.isFixedPointOp())
@@ -2769,9 +2751,8 @@
Value *Zero = llvm::Constant::getNullValue(Oper->getType());
Value *Result;
if (Oper->getType()->isFPOrFPVectorTy()) {
- llvm::IRBuilder<>::FastMathFlagGuard FMFG(Builder);
- setBuilderFlagsFromFPFeatures(Builder, CGF,
- E->getFPFeatures(CGF.getLangOpts()));
+ CodeGenFunction::CGFPOptionsRAII FPOptsRAII(
+ CGF, E->getFPFeatures(CGF.getLangOpts()));
Result = Builder.CreateFCmp(llvm::CmpInst::FCMP_OEQ, Oper, Zero, "cmp");
} else
Result = Builder.CreateICmp(llvm::CmpInst::ICMP_EQ, Oper, Zero, "cmp");
@@ -3183,8 +3164,7 @@
if (Ops.LHS->getType()->isFPOrFPVectorTy()) {
llvm::Value *Val;
- llvm::IRBuilder<>::FastMathFlagGuard FMFG(Builder);
- setBuilderFlagsFromFPFeatures(Builder, CGF, Ops.FPFeatures);
+ CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, Ops.FPFeatures);
Val = Builder.CreateFDiv(Ops.LHS, Ops.RHS, "div");
if (CGF.getLangOpts().OpenCL &&
!CGF.CGM.getCodeGenOpts().CorrectlyRoundedDivSqrt) {
@@ -3562,8 +3542,7 @@
return EmitOverflowCheckedBinOp(op);
if (op.LHS->getType()->isFPOrFPVectorTy()) {
- llvm::IRBuilder<>::FastMathFlagGuard FMFG(Builder);
- setBuilderFlagsFromFPFeatures(Builder, CGF, op.FPFeatures);
+ CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, op.FPFeatures);
// Try to form an fmuladd.
if (Value *FMulAdd = tryEmitFMulAdd(op, CGF, Builder))
return FMulAdd;
@@ -3750,8 +3729,7 @@
return EmitOverflowCheckedBinOp(op);
if (op.LHS->getType()->isFPOrFPVectorTy()) {
- llvm::IRBuilder<>::FastMathFlagGuard FMFG(Builder);
- setBuilderFlagsFromFPFeatures(Builder, CGF, op.FPFeatures);
+ CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, op.FPFeatures);
// Try to form an fmuladd.
if (Value *FMulAdd = tryEmitFMulAdd(op, CGF, Builder, true))
return FMulAdd;
@@ -4077,8 +4055,7 @@
if (BOInfo.isFixedPointOp()) {
Result = EmitFixedPointBinOp(BOInfo);
} else if (LHS->getType()->isFPOrFPVectorTy()) {
- llvm::IRBuilder<>::FastMathFlagGuard FMFG(Builder);
- setBuilderFlagsFromFPFeatures(Builder, CGF, BOInfo.FPFeatures);
+ CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, BOInfo.FPFeatures);
if (!IsSignaling)
Result = Builder.CreateFCmp(FCmpOpc, LHS, RHS, "cmp");
else
@@ -4231,9 +4208,8 @@
Value *RHS = Visit(E->getRHS());
Value *Zero = llvm::ConstantAggregateZero::get(LHS->getType());
if (LHS->getType()->isFPOrFPVectorTy()) {
- llvm::IRBuilder<>::FastMathFlagGuard FMFG(Builder);
- setBuilderFlagsFromFPFeatures(Builder, CGF,
- E->getFPFeatures(CGF.getLangOpts()));
+ CodeGenFunction::CGFPOptionsRAII FPOptsRAII(
+ CGF, E->getFPFeatures(CGF.getLangOpts()));
LHS = Builder.CreateFCmp(llvm::CmpInst::FCMP_UNE, LHS, Zero, "cmp");
RHS = Builder.CreateFCmp(llvm::CmpInst::FCMP_UNE, RHS, Zero, "cmp");
} else {
@@ -4318,9 +4294,8 @@
Value *RHS = Visit(E->getRHS());
Value *Zero = llvm::ConstantAggregateZero::get(LHS->getType());
if (LHS->getType()->isFPOrFPVectorTy()) {
- llvm::IRBuilder<>::FastMathFlagGuard FMFG(Builder);
- setBuilderFlagsFromFPFeatures(Builder, CGF,
- E->getFPFeatures(CGF.getLangOpts()));
+ CodeGenFunction::CGFPOptionsRAII FPOptsRAII(
+ CGF, E->getFPFeatures(CGF.getLangOpts()));
LHS = Builder.CreateFCmp(llvm::CmpInst::FCMP_UNE, LHS, Zero, "cmp");
RHS = Builder.CreateFCmp(llvm::CmpInst::FCMP_UNE, RHS, Zero, "cmp");
} else {