[PATCH] D64101: [LoopUnroll] fix cloning callbr

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

The question is whether something like the following is legal:

  void bar(void) {
      long temp = 0;
      #pragma GCC unroll 3
      for (int j = 0; j < 3; ++j) {
          asm goto("lea %l2(%%rip), %%rax\n"
                   "cmp $0, %0\n"
                   "jne 1f\n"
                   "mov %%rax, %0\n"
                   "1:\n"
                   "jmp *%0\n" :: "m"(temp), "r"(j) :"memory","rax": baz);
          baz:;
      }
  }
  int main() { bar(); }

I guess the answer is that no, it isn't legal, given gcc's behavior.  But there's nothing in LangRef that forbids it... we need some rule that ties the value passed to the "X" constraint to the actual successor.


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  https://reviews.llvm.org/D64101/new/

https://reviews.llvm.org/D64101