[PATCH] Fix simplify_comparison in the combiner (PR rtl-optimization/61673)

[Jakub Jelinek]

On Thu, Jul 03, 2014 at 08:35:14AM +0200, Jakub Jelinek wrote:
> Bootstrapped/regtested on x86_64-linux, i686-linux and s390{,x}-linux.  Ok
> for trunk/4.9?

I'd like to see this in 4.9.1, it is a wrong-code regression from 4.8.x,
so I'm pinging this now:

> 2014-07-03  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR rtl-optimization/61673
> 	* combine.c (simplify_comparison): Test just mode's sign bit
> 	in tmode rather than the sign bit and any bits above it.
> 
> 	* gcc.c-torture/execute/pr61673.c: New test.
> 
> --- gcc/combine.c.jj	2014-03-28 20:49:52.892077022 +0100
> +++ gcc/combine.c	2014-07-02 16:56:02.260456040 +0200
> @@ -11987,7 +11987,7 @@ simplify_comparison (enum rtx_code code,
>  		= (unsigned HOST_WIDE_INT) 1 << (GET_MODE_BITSIZE (mode) - 1);
>  	      op0 = simplify_gen_binary (AND, tmode,
>  					 gen_lowpart (tmode, op0),
> -					 gen_int_mode (sign, mode));
> +					 gen_int_mode (sign, tmode));
>  	      code = (code == LT) ? NE : EQ;
>  	      break;
>  	    }
> --- gcc/testsuite/gcc.c-torture/execute/pr61673.c.jj	2014-07-02 17:17:01.398908630 +0200
> +++ gcc/testsuite/gcc.c-torture/execute/pr61673.c	2014-07-02 17:12:36.000000000 +0200
> @@ -0,0 +1,50 @@
> +/* PR rtl-optimization/61673 */
> +
> +char e;
> +
> +__attribute__((noinline, noclone)) void
> +bar (char x)
> +{
> +  if (x != 0x54 && x != (char) 0x87)
> +    __builtin_abort ();
> +}
> +
> +__attribute__((noinline, noclone)) void
> +foo (const char *x)
> +{
> +  char d = x[0];
> +  int c = d;
> +  if ((c >= 0 && c <= 0x7f) == 0)
> +    e = d;
> +  bar (d);
> +}
> +
> +__attribute__((noinline, noclone)) void
> +baz (const char *x)
> +{
> +  char d = x[0];
> +  int c = d;
> +  if ((c >= 0 && c <= 0x7f) == 0)
> +    e = d;
> +}
> +
> +int
> +main ()
> +{
> +  const char c[] = { 0x54, 0x87 };
> +  e = 0x21;
> +  foo (c);
> +  if (e != 0x21)
> +    __builtin_abort ();
> +  foo (c + 1);
> +  if (e != (char) 0x87)
> +    __builtin_abort ();
> +  e = 0x21;
> +  baz (c);
> +  if (e != 0x21)
> +    __builtin_abort ();
> +  baz (c + 1);
> +  if (e != (char) 0x87)
> +    __builtin_abort ();
> +  return 0;
> +}

	Jakub