dim added inline comments.
================
Comment at: lib/Basic/Targets/X86.cpp:1049
+ if (HasLAHFSAHF)
+ Builder.defineMacro("__LAHFSAHF__");
----------------
craig.topper wrote:
> Does gcc define this? It's such a low level instruction I have a hard time
> believing this define would be useful.
I tried gcc 6, 7 and 8, and while they do expose stuff like `__POPCNT__`, I see
no `__LAHFSAHF__`. I am supposing Jonathan's original intent with this was to
make it easily testable in source, so you can insert the right assembly for the
target CPU. The same could really be said for things like `__RDSEED__`, and
some other defines...
Repository:
rC Clang
https://reviews.llvm.org/D43394
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