add fast-math-flags to 'call' instructions (PR21290)
This patch adds optional fast-math-flags (the same that apply to fmul/fadd/fsub/fdiv/frem/fcmp)
to call instructions in IR. Follow-up patches would use these flags in LibCallSimplifier, add
support to clang, and extend FMF to the DAG for calls.
Motivating example:
%y = fmul fast float %x, %x
%z = tail call float @sqrtf(float %y)
We'd like to be able to optimize sqrt(x*x) into fabs(x). We do this today using a function-wide
attribute for unsafe-math, but we really want to trigger on the instructions themselves:
%z = tail call fast float @sqrtf(float %y)
because in an LTO build it's possible that calls with fast semantics have been inlined into a
function with non-fast semantics.
The code changes and tests are based on the recent commits that added "notail":
http://reviews.llvm.org/rL252368
and added FMF to fcmp:
http://reviews.llvm.org/rL241901
Differential Revision: http://reviews.llvm.org/D14707
llvm-svn: 255555
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 3d43f81..0b28809 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -5603,14 +5603,14 @@
}
/// ParseCall
-/// ::= 'call' OptionalCallingConv OptionalAttrs Type Value
-/// ParameterList OptionalAttrs
-/// ::= 'tail' 'call' OptionalCallingConv OptionalAttrs Type Value
-/// ParameterList OptionalAttrs
-/// ::= 'musttail' 'call' OptionalCallingConv OptionalAttrs Type Value
-/// ParameterList OptionalAttrs
-/// ::= 'notail' 'call' OptionalCallingConv OptionalAttrs Type Value
-/// ParameterList OptionalAttrs
+/// ::= 'call' OptionalFastMathFlags OptionalCallingConv
+/// OptionalAttrs Type Value ParameterList OptionalAttrs
+/// ::= 'tail' 'call' OptionalFastMathFlags OptionalCallingConv
+/// OptionalAttrs Type Value ParameterList OptionalAttrs
+/// ::= 'musttail' 'call' OptionalFastMathFlags OptionalCallingConv
+/// OptionalAttrs Type Value ParameterList OptionalAttrs
+/// ::= 'notail' 'call' OptionalFastMathFlags OptionalCallingConv
+/// OptionalAttrs Type Value ParameterList OptionalAttrs
bool LLParser::ParseCall(Instruction *&Inst, PerFunctionState &PFS,
CallInst::TailCallKind TCK) {
AttrBuilder RetAttrs, FnAttrs;
@@ -5624,10 +5624,14 @@
SmallVector<OperandBundleDef, 2> BundleList;
LocTy CallLoc = Lex.getLoc();
- if ((TCK != CallInst::TCK_None &&
- ParseToken(lltok::kw_call,
- "expected 'tail call', 'musttail call', or 'notail call'")) ||
- ParseOptionalCallingConv(CC) || ParseOptionalReturnAttrs(RetAttrs) ||
+ if (TCK != CallInst::TCK_None &&
+ ParseToken(lltok::kw_call,
+ "expected 'tail call', 'musttail call', or 'notail call'"))
+ return true;
+
+ FastMathFlags FMF = EatFastMathFlagsIfPresent();
+
+ if (ParseOptionalCallingConv(CC) || ParseOptionalReturnAttrs(RetAttrs) ||
ParseType(RetType, RetTypeLoc, true /*void allowed*/) ||
ParseValID(CalleeID) ||
ParseParameterList(ArgList, PFS, TCK == CallInst::TCK_MustTail,
@@ -5636,6 +5640,10 @@
ParseOptionalOperandBundles(BundleList, PFS))
return true;
+ if (FMF.any() && !RetType->isFPOrFPVectorTy())
+ return Error(CallLoc, "fast-math-flags specified for call without "
+ "floating-point scalar or vector return type");
+
// If RetType is a non-function pointer type, then this is the short syntax
// for the call, which means that RetType is just the return type. Infer the
// rest of the function argument types from the arguments that are present.
@@ -5708,6 +5716,8 @@
CallInst *CI = CallInst::Create(Ty, Callee, Args, BundleList);
CI->setTailCallKind(TCK);
CI->setCallingConv(CC);
+ if (FMF.any())
+ CI->setFastMathFlags(FMF);
CI->setAttributes(PAL);
ForwardRefAttrGroups[CI] = FwdRefAttrGrps;
Inst = CI;