[PATCH] D142178: [X86] Change precision control to FP80 during u64->fp32 conversion on Windows.

Thu Feb 2 12:53:04 PST 2023

craig.topper added inline comments.

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Comment at: llvm/test/CodeGen/X86/uint64-to-float.ll:64
+; X86-WIN-NEXT:    fldcw {{[0-9]+}}(%esp)
+; X86-WIN-NEXT:    fadds __real at 5f80000000000000(,%eax,4)
+; X86-WIN-NEXT:    fldcw {{[0-9]+}}(%esp)
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icedrocket wrote:
> craig.topper wrote:
> > icedrocket wrote:
> > > I checked the assembly generated by clang and it seems that fadds is split into fld and fadd.
> > That's weird. Do you have a C file you can share?
> The file is same as the summary's code in D141074. I think that there is no actual `fadds` instruction in x87 and end up split into two instructions.
Did you check the assembly without optimizations enabled?  Folding the load into the fadd is only done with optimizations enabled.

Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D142178/new/

https://reviews.llvm.org/D142178