[Bug target/63966] [5 regression] inconsistent operand constraints compiling build libcpp

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63966

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Uroš Bizjak from comment #5)
> Can you please test this patch:
> 
> --cut here--
> Index: lex.c
> ===================================================================
> --- lex.c       (revision 217789)
> +++ lex.c       (working copy)
> @@ -471,7 +471,11 @@
>  
>  /* Check the CPU capabilities.  */
>  
> +#if (GCC_VERSION >= 5000)
>  #include "../gcc/config/i386/cpuid.h"
> +#else
> +#include <cpuid.h>
> +#endif
>  
>  typedef const uchar * (*search_line_fast_type) (const uchar *, const uchar
> *);
>  static search_line_fast_type search_line_fast;
> --cut here--

That assumes there is <cpuid.h> provided by the system compiler.
The code is guarded with
#if (GCC_VERSION >= 4005) && (defined(__i386__) || defined(__x86_64__)) &&
!(defined(__sun__) && defined(__svr4__))
but doesn't clang and icc pretend to be some versions of GCC?
I think better would be to include #include "../gcc/config/i386/cpuid.h"
only if GCC_VERSION >= 5000 (or perhaps that or __PIC__ not defined or
__x86_64__ defined), and otherwise not use __get_cpuid at all, just statically
decide based on minimum value.
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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/63986] [5 Regression][SH] gcc.target/sh/pr51244-15.c failures
Date: Thu, 20 Nov 2014 10:21:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idc986

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
                 CC|                            |ppalka at gcc dot gnu.org,
                   |                            |rguenth at gcc dot gnu.org
           Assignee|rguenth at gcc dot gnu.org         |unassigned at gcc dot gnu.org

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ok, now already existing forwprop code gets fed with

  <bb 2>:
  _3 = a_2(D) == 0;
  x_4 = (char) _3;
  _7 = ~_3;
  _8 = (int) _7;
  MEM[(int *)d_5(D) + 8B] = _8;
  if (x_4 != 0)

where we now in the first forwprop pass identified the opportunity
to use ~_3 instead of x_4 == 0 thus x_4 is now no longer multi-use.
This makes us optimize if (x_4 != 0) to if (_3 != 0) which we
re-optimize in fold_gimple_cond now to '_3' and then of course
if (_3 != 0) (err, and we return "changed"....) which means we
now propagate _again_ via forward_propagate_into_gimple_cond
which now specifically allows aggressive forwarding of compares,
bypassing single-use restrictions.  See

2014-11-16  Patrick Palka  <ppalka@gcc.gnu.org>

        PR middle-end/63790
        * tree-ssa-forwprop.c (forward_propagate_into_comparison_1):
        Always combine comparisons or conversions from booleans.

thus me fixing my "mistake" does not help anymore.

I suppose RTL CSE cannot CSE flag register sets...?

Btw, my previous comment was incorrect - the code is what is now produced
on trunk while on the 4.9 branch we create

test_0:
.LFB0:
        .cfi_startproc
        testl   %edi, %edi
        movl    %edx, %eax
        sete    %r8b
        movl    %r8d, %edi
        xorl    $1, %edi
        testb   %r8b, %r8b
        movzbl  %dil, %edi
        cmovne  %esi, %eax
        movl    %edi, 8(%rcx)
        ret

which means code generation improved for x86...