[PATCH] D115471: [clang] number labels in asm goto strings after tied inputs

[Nick Desaulniers via Phabricator via cfe-commits]

nickdesaulniers created this revision.
nickdesaulniers added reviewers: void, efriedma, jyknight, craig.topper.
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I noticed that the following case would compile in Clang but not GCC:

  void *x(void) {
    void *p = &&foo;
    asm goto ("# %0\n\t# %l1":"+r"(p):::foo);
    foo:;
    return p;
  }

Changing the output template above from %l2 would compile in GCC but not
Clang.

This demonstrates that when using tied outputs (say via the "+r" output
constraint), the hidden inputs occur or are numbered BEFORE the labels,
at least with GCC.

For the sake of compatibility, I think it's worthwhile to just make this
change.

It's better to use symbolic names for compatibility (especially now
between released version of Clang that support asm goto with outputs).
ie. %l1 from the above would be %l[foo].

Also, I cleaned up some cruft in GCCAsmStmt::getNamedOperand. AFAICT,
NumPlusOperands was no longer used, though I couldn't find which commit
didn't clean that up correctly.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D115471

Files:
  clang/lib/AST/Stmt.cpp
  clang/lib/CodeGen/CGStmt.cpp
  clang/test/CodeGen/asm-goto.c

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