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Date: Mon, 04 Jul 2005 09:19:00 -0000
From: "kostikbel at ukr dot net" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20050704091851.22292.kostikbel@ukr.net>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug c/22292] New: ICE and wrong code gen with _mm_loadl_pd/__builtin_ia32_loadlpd
X-Bugzilla-Reason: CC
X-SW-Source: 2005-07/txt/msg00301.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

The following code

#include <xmmintrin.h>

extern "C" double
fadd(double a, double b)
{
        __m128d a1;
        __m128d b1;
        __m128d c;
        double res;

        _mm_loadl_pd(a1, &a);
        _mm_loadl_pd(b1, &b);
        c = _mm_add_sd(a1, b1);
        _mm_storel_pd(&res, c);
        return res;
}

when compiled with
CC3 -msse3 -march=prescott -c fadd.C
leads to ICE:

/usr/local/opt/gcc-3.4.4/lib/gcc/i386-little-freebsd5/3.4.4/include/emmintrin.h:
In function `void _mm_storel_pd(double*, double __vector__)':
/usr/local/opt/gcc-3.4.4/lib/gcc/i386-little-freebsd5/3.4.4/include/emmintrin.h:959:
internal compiler error: in instantiate_virtual_regs_lossage, at function.c:3765

CC3 is
deviant% CC3 -v
Reading specs from /usr/local/opt/gcc-3.4.4/lib/gcc/i386-little-freebsd5/3.4.4/specs
Configured with: ../gcc-3.4.4/configure --prefix=/usr/local/opt/gcc-3.4.4
--enable-shared --enable-threads --with-as=/usr/local/opt/binutils/bin/as
--with-ld=/usr/local/opt/binutils/bin/ld
--enable-languages=c,c++,f77,objc,ada,java --disable-nls --enable-long-long
--host=i386-little-freebsd5
Thread model: posix
gcc version 3.4.4

When compiled with
deviant% CC3 -msse3 -march=prescott -O -c fadd.C
it leads to wrong code:

deviant% objdump --disassemble fadd.o                            ~/work/gcc-xmm

fadd.o:     file format elf32-i386-freebsd

Disassembly of section .text:

00000000 <_Z4fadddd>:
   0:   55                      push   %ebp
   1:   89 e5                   mov    %esp,%ebp
   3:   83 ec 08                sub    $0x8,%esp
   6:   f2 0f 58 c0             addsd  %xmm0,%xmm0
   a:   66 0f 13 45 f8          movlpd %xmm0,0xfffffff8(%ebp)
   f:   dd 45 f8                fldl   0xfffffff8(%ebp)
  12:   c9                      leave  
  13:   c3                      ret

Note that arguments of the fadd function are never accessed.

gcc 4.0.0 does not ICE without optimization, but with or without -O, it
generates wrong code (for -O, the code is identical to gcc 3.4.4).

Substitution of _mm_loadl_pd with __builtin_ia32_loadlpd does not change
anything.

N.B. I do not insert preprocessed file since code snippet that shows problem
uses only headers supplied by gcc itself. Also, this problem appears both
under 3.4 and 4.0. If needed, I will attach (relatively large) .i files.

-- 
           Summary: ICE and wrong code gen with
                    _mm_loadl_pd/__builtin_ia32_loadlpd
           Product: gcc
           Version: 3.4.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kostikbel at ukr dot net
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i386-*-freebsd5
  GCC host triplet: i386-*-freebsd5
GCC target triplet: i386-*-freebsd5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22292