[LLVMdev] Fast-math flags in constant expressions
milseman at apple.com
Tue Dec 2 14:46:32 PST 2014
Out of curiosity, how would you envision fast-math flags interacting with constant expressions? Off the top of my head, I can’t think of any flags that would be relevant if the expression can just be constant-folded away at full precision anyways.
> On Nov 28, 2014, at 4:56 AM, Sergey Dmitrouk <sdmitrouk at accesssoftek.com> wrote:
> Doesn't look like a bug, more like a limitation of constant expressions
> as llvm::BinaryConstantExpr doesn't have FastMastFlags.
> On Thu, Nov 27, 2014 at 03:39:20PM +0200, Sergey Dmitrouk wrote:
>> I'm wondering why lib/AsmParser/LLParser handles fast-math flags in the
>> following IR:
>> %val = fmul nnan double 1.0, 1.0
>> but doesn't allow any flags if "fmul" is inside "phi":
>> %val = phi double [ fmul (double 1.0, double 1.0), %cond.true ],
>> [ fmul (double 1.0, double 1.0), %cond.false ]
>> LLParser::ParseValID(...) could call EatFastMathFlagsIfPresent() to
>> handle fast-math flags, but it doesn't. Is this intended or a bug?
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
More information about the llvm-dev