[CodeGen] fix const-ness of cbrt and fma
cbrt() is always constant because it can't overflow or underflow. Therefore, it can't set errno.
fma() is not always constant because it can overflow or underflow. Therefore, it can set errno.
But we know that it never sets errno on GNU / MSVC, so make it constant in those environments.
Differential Revision: https://reviews.llvm.org/D39641
llvm-svn: 318093
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 2d1b4f4..4c5e3a4 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -2109,15 +2109,11 @@
case Builtin::BIfmal:
case Builtin::BI__builtin_fma:
case Builtin::BI__builtin_fmaf:
- case Builtin::BI__builtin_fmal: {
- // Rewrite fma to intrinsic.
- Value *FirstArg = EmitScalarExpr(E->getArg(0));
- llvm::Type *ArgType = FirstArg->getType();
- Value *F = CGM.getIntrinsic(Intrinsic::fma, ArgType);
- return RValue::get(
- Builder.CreateCall(F, {FirstArg, EmitScalarExpr(E->getArg(1)),
- EmitScalarExpr(E->getArg(2))}));
- }
+ case Builtin::BI__builtin_fmal:
+ // A constant libcall or builtin is equivalent to the LLVM intrinsic.
+ if (FD->hasAttr<ConstAttr>())
+ return RValue::get(emitTernaryBuiltin(*this, E, Intrinsic::fma));
+ break;
case Builtin::BI__builtin_signbit:
case Builtin::BI__builtin_signbitf: