asavonic added inline comments.
================
Comment at: clang/lib/Basic/Targets/X86.cpp:385
- if (!HasX87) {
- if (LongDoubleFormat == &llvm::APFloat::x87DoubleExtended())
- HasLongDouble = false;
- if (getTriple().getArch() == llvm::Triple::x86)
- HasFPReturn = false;
- }
+ if (!HasX87 && getTriple().getArch() == llvm::Triple::x86_64 &&
+ LongDoubleFormat == &llvm::APFloat::x87DoubleExtended())
----------------
I see that D112143 changed the ABI so that FP return values do not use x87
registers on i386. Therefore HasFPReturn flag can be removed.
However, operations with long double (x87 80-bit) should still be unsupported
on both targets, because IIRC there is no SSE equivalent for them. GCC compiles
them as soft-fp when -mno-x87 is set, but I haven't found 80-bit soft-fp
implementation in LLVM.
```
long double baz(long double a, long double b) {
return a + b;
}
```
```
baz:
[...]
call __addxf3
```
For some reason GCC only does this for for i386 target, for x86_64 it just
emits the diagnostic about disabled x87.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D114162/new/
https://reviews.llvm.org/D114162
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