From fa54acedd1fd1183143c0a7f4b77554fd8cdb1ec Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Mon, 14 Dec 2015 21:59:03 +0000 Subject: 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 --- llvm/lib/Bitcode/Reader/BitcodeReader.cpp | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'llvm/lib/Bitcode/Reader/BitcodeReader.cpp') diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp index 210ffd8..d59f128 100644 --- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp +++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp @@ -5006,7 +5006,7 @@ std::error_code BitcodeReader::parseFunctionBody(Function *F) { break; } case bitc::FUNC_CODE_INST_CALL: { - // CALL: [paramattrs, cc, fnty, fnid, arg0, arg1...] + // CALL: [paramattrs, cc, fmf, fnty, fnid, arg0, arg1...] if (Record.size() < 3) return error("Invalid record"); @@ -5014,6 +5014,13 @@ std::error_code BitcodeReader::parseFunctionBody(Function *F) { AttributeSet PAL = getAttributes(Record[OpNum++]); unsigned CCInfo = Record[OpNum++]; + FastMathFlags FMF; + if ((CCInfo >> bitc::CALL_FMF) & 1) { + FMF = getDecodedFastMathFlags(Record[OpNum++]); + if (!FMF.any()) + return error("Fast math flags indicator set for call with no FMF"); + } + FunctionType *FTy = nullptr; if (CCInfo >> bitc::CALL_EXPLICIT_TYPE & 1 && !(FTy = dyn_cast(getTypeByID(Record[OpNum++])))) @@ -5075,6 +5082,12 @@ std::error_code BitcodeReader::parseFunctionBody(Function *F) { TCK = CallInst::TCK_NoTail; cast(I)->setTailCallKind(TCK); cast(I)->setAttributes(PAL); + if (FMF.any()) { + if (!isa(I)) + return error("Fast-math-flags specified for call without " + "floating-point scalar or vector return type"); + I->setFastMathFlags(FMF); + } break; } case bitc::FUNC_CODE_INST_VAARG: { // VAARG: [valistty, valist, instty] -- cgit v1.1