[Bug 1560686] Re: Invalid assembly is generated when using intel syntax

[Matthias Klose]

It is because ST is a register.  To use -masm=intel, one should avoid
using registers, like st, rax, xmm0, .... as variables.

** Changed in: gcc-5 (Ubuntu)
       Status: New => Invalid

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Title:
  Invalid assembly is generated when using intel syntax

Status in gcc-5 package in Ubuntu:
  Invalid

Bug description:
  Invalid assembly code is generated when intel syntax (-masm=intel) is
  used and there are any symbols of the same name as CPU register. For
  example:

  int ST = 42;
  int main() {
  	return ST;
  }

  Will produce messages like:
  /tmp/ccglHDgh.s: Assembler messages:
  /tmp/ccglHDgh.s:21: Error: invalid use of register

  The problem is that GCC will generate nonsense like that:
  mov eax, DWORD PTR ST[rip]

  In case of such trivial example, it is very easy to find what the
  problem is but it can be really tricky to find the cause in larger
  projects. I expect that the compiler should at least generate some
  clear warning that using such names can cause problems.

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