[all-commits] [llvm/llvm-project] 7c2d51: [asm] Allow labels as operands in intel asm syntax

[Nico Weber via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7c2d51474aae87635de8f9ecbcdf622d376269a9
      https://github.com/llvm/llvm-project/commit/7c2d51474aae87635de8f9ecbcdf622d376269a9
  Author: Nico Weber <thakis at chromium.org>
  Date:   2021-11-22 (Mon, 22 Nov 2021)

  Changed paths:
    M llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
    M llvm/test/CodeGen/X86/asm-block-labels.ll

  Log Message:
  -----------
  [asm] Allow labels as operands in intel asm syntax

This makes a line in llvm/test/CodeGen/X86/asm-block-labels.ll pass
with `asm inteldialect` too.

I don't know if this is something one can hit in practice with inline
asm. The test is from 2007 (4646aa3e337aa) but in 2009 blockaddr was
introduced and e.g. `__asm__ __volatile__("brl %0" :: "X"(&&foo) : "memory");`
compiles to

    call void asm sideeffect "brl $0", "X,..."(i8* blockaddress(@func, %1))

nowadays (thanks to jrtc27 for that example!).

(6c4d255bf3d64 switched clang to blockaddress on an opt-in basis,
e4801f7844bb added docs for it, 31b132c0b781 added IR support.)

I half-heartedly tried to build clang 2.8 locally, but it didn't
just build. And 2.8 didn't have a prebuilt clang binary yet.

The motivation is to make EmitGCCInlineAsmStr() and EmitMSInlineAsmStr()
more alike, and maybe we should delete this code form EmitGCCInlineAsmStr()
instead. But since it's just 3 lines and it's reachable from LLVM IR,
let's do the safer thing for now.

Differential Revision: https://reviews.llvm.org/D114329