[Bug c++/19263] New: [g++-3.4.3 regression]: wrong-code: explicit inicialization of v8qi miscompiled

[Bug c++/19263] New: [g++-3.4.3 regression]: wrong-code: explicit inicialization of v8qi miscompiled

[smelkov at mph1 dot phys dot spbu dot ru]

In the following code sample the line 
v8qi val8 = {v,v,v,v,v,v,v,v}; 
 
is miscompiled to smth like 
v8qi val8 = {0,0,0,0,0,0,0,0}; 
 
 
---v8qi-init.cpp--- 
typedef int v8qi __attribute__ ((mode(V8QI))); 
 
static unsigned char S[8]; 
 
void do_subs(unsigned char v) 
{ 
    v8qi  val8 = {v,v,v,v,v,v,v,v}; 
    v8qi* s = (v8qi*)&S[0]; 
 
    *s = __builtin_ia32_psubusb(*s, val8); 
} 
 
 
int main() 
{ 
    int i; 
 
    for (i=0;i<8;++i) 
        S[i] = 0x55; 
 
 
    do_subs(0x54); 
 
    for (i=0;i<8;++i) 
        if (S[i] != 0x01) 
            return 1; 
 
 
    return 0; 
} 
--- 
 
[kirr@tugrik gcc-v8qi-bug]$ g++ -v 
Reading specs from /usr/local/gcc-3.4.3-nocheck-native/lib/gcc/i686-pc-linux-gnu/3.4.3/specs 
Configured with: ../gcc-3.4.3/configure --prefix=/usr/local/gcc-3.4.3-nocheck-native 
--with-gnu-as --with-gnu-ld --enable-threads=posix --with-arch=pentium3 
--with-tune=pentium4 --enable-__cxa_atexit --enable-languages=c,c++,java,f77,ada 
--disable-checking --disable-nls 
Thread model: posix 
gcc version 3.4.3 
 
[kirr@tugrik gcc-v8qi-bug]$ g++ -g -Wall -march=i686 -mmmx v8qi-init.cpp  
[kirr@tugrik gcc-v8qi-bug]$ ./a.out  
[kirr@tugrik gcc-v8qi-bug]$ echo $? 
1 
 
--- 
with g++-3.4.2 it is ok, so it is a regression. 
please also note, that with gcc-3.4.3 it is also ok, so it is g++ specific (???) 
 
here are assembly parts: 
 
---g++-3.4.3--- 
void do_subs(unsigned char v) 
{ 
 8048374:       55                      push   %ebp 
 8048375:       89 e5                   mov    %esp,%ebp 
 8048377:       83 ec 18                sub    $0x18,%esp 
 804837a:       8b 45 08                mov    0x8(%ebp),%eax 
 804837d:       88 45 ff                mov    %al,0xffffffff(%ebp) 
    v8qi  val8 = {v,v,v,v,v,v,v,v}; 
 8048380:       0f ef c0                pxor   %mm0,%mm0 
 8048383:       0f 7f 45 f0             movq   %mm0,0xfffffff0(%ebp) 
    v8qi* s = (v8qi*)&S[0]; 
 8048387:       c7 45 ec f4 95 04 08    movl   $0x80495f4,0xffffffec(%ebp) 
  
    *s = __builtin_ia32_psubusb(*s, val8); 
 804838e:       8b 55 ec                mov    0xffffffec(%ebp),%edx 
 8048391:       8b 45 ec                mov    0xffffffec(%ebp),%eax 
 8048394:       0f 6f 00                movq   (%eax),%mm0 
 8048397:       0f d8 45 f0             psubusb 0xfffffff0(%ebp),%mm0 
 804839b:       0f 7f 02                movq   %mm0,(%edx) 
} 
 804839e:       c9                      leave   
 804839f:       c3                      ret 
--- 
 
note: pxor %mm0,%mm0 after "val8=..." 
 
---g++-3.4.2--- 
void do_subs(unsigned char v) 
{ 
 8048374:       55                      push   %ebp 
 8048375:       89 e5                   mov    %esp,%ebp 
 8048377:       83 ec 18                sub    $0x18,%esp 
 804837a:       8b 45 08                mov    0x8(%ebp),%eax 
 804837d:       88 45 ff                mov    %al,0xffffffff(%ebp) 
    v8qi  val8 = {v,v,v,v,v,v,v,v}; 
 8048380:       0f b6 45 ff             movzbl 0xffffffff(%ebp),%eax 
 8048384:       88 45 f0                mov    %al,0xfffffff0(%ebp) 
 8048387:       0f b6 45 ff             movzbl 0xffffffff(%ebp),%eax 
 804838b:       88 45 f1                mov    %al,0xfffffff1(%ebp) 
 804838e:       0f b6 45 ff             movzbl 0xffffffff(%ebp),%eax 
 8048392:       88 45 f2                mov    %al,0xfffffff2(%ebp) 
 8048395:       0f b6 45 ff             movzbl 0xffffffff(%ebp),%eax 
 8048399:       88 45 f3                mov    %al,0xfffffff3(%ebp) 
 804839c:       0f b6 45 ff             movzbl 0xffffffff(%ebp),%eax 
 80483a0:       88 45 f4                mov    %al,0xfffffff4(%ebp) 
 80483a3:       0f b6 45 ff             movzbl 0xffffffff(%ebp),%eax 
 80483a7:       88 45 f5                mov    %al,0xfffffff5(%ebp) 
 80483aa:       0f b6 45 ff             movzbl 0xffffffff(%ebp),%eax 
 80483ae:       88 45 f6                mov    %al,0xfffffff6(%ebp) 
 80483b1:       0f b6 45 ff             movzbl 0xffffffff(%ebp),%eax 
 80483b5:       88 45 f7                mov    %al,0xfffffff7(%ebp) 
    v8qi* s = (v8qi*)&S[0]; 
 80483b8:       c7 45 ec 24 96 04 08    movl   $0x8049624,0xffffffec(%ebp) 
 
    *s = __builtin_ia32_psubusb(*s, val8); 
 80483bf:       8b 55 ec                mov    0xffffffec(%ebp),%edx 
 80483c2:       8b 45 ec                mov    0xffffffec(%ebp),%eax 
 80483c5:       0f 6f 00                movq   (%eax),%mm0 
 80483c8:       0f d8 45 f0             psubusb 0xfffffff0(%ebp),%mm0 
 80483cc:       0f 7f 02                movq   %mm0,(%edx) 
} 
 80483cf:       c9                      leave 
 80483d0:       c3                      ret 
 80483d1:       90                      nop 
---

-- 
           Summary: [g++-3.4.3 regression]: wrong-code: explicit
                    inicialization of v8qi miscompiled
           Product: gcc
           Version: 3.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: smelkov at mph1 dot phys dot spbu dot ru
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit inicialization of v8qi miscompiled

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-05 14:48 -------
Confirmed.
Here is the reduced testcase without any x86 builtins usage:
typedef signed char v8qi __attribute__ ((vector_size(8)));

extern "C" void abort(void);

static unsigned char S[8];

void do_subs(unsigned char v)
{
    v8qi  val8 = {v,v,v,v,v,v,v,v};
    v8qi* s = (v8qi*)&S[0];

    *s = val8;
}


int main()
{
    int i;
    do_subs(0x1);
    for (i=0;i<8;++i)
        if (S[i] != 0x01)
            abort();
    return 0;
}

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |wrong-code
      Known to fail|                            |4.0.0
      Known to work|                            |3.4.0
   Last reconfirmed|0000-00-00 00:00:00         |2005-01-05 14:48:26
               date|                            |
            Summary|[g++-3.4.3 regression]:     |[3.4/4.0 regression]: wrong-
                   |wrong-code: explicit        |code: explicit
                   |inicialization of v8qi      |inicialization of v8qi
                   |miscompiled                 |miscompiled
   Target Milestone|---                         |3.4.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit inicialization of v8qi miscompiled

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-05 14:57 -------
Using Phil's regression hunter, I found the failure was caused between 20041026 and 20041103.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit inicialization of v8qi miscompiled

[jakub at gcc dot gnu dot org]

------- Additional Comments From jakub at gcc dot gnu dot org  2005-01-12 17:30 -------
Yeah, with PR c++/15172, http://gcc.gnu.org/ml/gcc-patches/2004-11/msg00001.html


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mark at codesourcery dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit inicialization of v8qi miscompiled

[jakub at gcc dot gnu dot org]

------- Additional Comments From jakub at gcc dot gnu dot org  2005-01-12 18:00 -------
This seems to be because of the CONSTRUCTOR_ELTS (init) = NULL;
added in http://gcc.gnu.org/ml/gcc-patches/2004-01/msg00832.html
by Richard.
If I remove it, the testcase works, as well as this bigger one below.
Wiping the initializers of the vector can't be right, so either that line
can be just deleted, or we want to create zero vector and then initialize
it field by field with the original values.
typedef signed char v8qi __attribute__ ((vector_size (8)));

extern "C" void abort (void);

static unsigned char S[16];

struct A
{
  int i;
  v8qi j, k;
  int l;
};

void
foo (unsigned char v)
{
  A a = { 1, { v, v, v, v, v, v, v, v },
             { v + 1, v + 1, v + 1, v + 1, v + 1, v + 1, v + 1, v + 1 }, 3 };
  v8qi *s = (v8qi *) & S[0];
  *s = a.j;
  s[1] = a.k;
}

void
bar (unsigned char v)
{
  v8qi val8 = { v, v, v, v, v, v, v, v };
  v8qi *s = (v8qi *) & S[0];
  *s = val8;
}

int
main ()
{
  int i;
  foo (1);
  for (i = 0; i < 8; ++i)
    if (S[i] != 1)
      abort ();
  for (; i < 16; ++i)
    if (S[i] != 2)
      abort ();
  bar (3);
  for (i = 0; i < 8; ++i)
    if (S[i] != 3)
      abort ();
  return 0;
}



-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit inicialization of v8qi miscompiled

[jakub at gcc dot gnu dot org]

------- Additional Comments From jakub at gcc dot gnu dot org  2005-01-12 18:30 -------
Tested to also test static initializers:
typedef signed char v8qi __attribute__ ((vector_size (8)));

extern "C" void abort (void);

static unsigned char S[16];

struct A
{
  int i;
  v8qi j, k;
  int l;
};

void
foo (unsigned char v)
{
  A a = { 1, { v, v, v, v, v, v, v, v },
          { v + 1, v + 1, v + 1, v + 1, v + 1, v + 1, v + 1, v + 1 }, 3 };
  v8qi *s = (v8qi *) &S[0];
  *s = a.j;
  s[1] = a.k;
}

void
bar (unsigned char v)
{
  v8qi val8 = { v, v, v, v, v, v, v, v };
  v8qi *s = (v8qi *) &S[0];
  *s = val8;
}

int n = 5, cnt;

int
num (void)
{
  ++cnt;
  return n;
}

void
baz (void)
{
  static A a = { 0, { num (), num (), num (), num (), 6, 6, 6, 6 },
                 { 7, 7, 7, 7, 8, 8, 8, 8 }, 0 };
  v8qi *s = (v8qi *) &S[0];
  *s = a.j;
  s[1] = a.k;
}

int
main ()
{
  int i;
  foo (1);
  for (i = 0; i < 8; ++i)
    if (S[i] != 1)
      abort ();
  for (; i < 16; ++i)
    if (S[i] != 2)
      abort ();
  bar (3);
  for (i = 0; i < 8; ++i)
    if (S[i] != 3)
      abort ();
  baz ();
  if (cnt != 4)
    abort ();
  for (i = 0; i < 16; ++i)
    if (S[i] != 5 + (i / 4))
      abort ();
  return 0;
}

Works with G++ 3.2.x, fails with 3.4.x and mainline, even with:
--- typeck2.c.jj        2005-01-12 18:34:32.000000000 +0100
+++ typeck2.c   2005-01-12 19:19:28.602047217 +0100
@@ -348,8 +348,9 @@ split_nonconstant_init_1 (tree dest, tre
     case VECTOR_TYPE:
       if (!initializer_constant_valid_p (init, type))
        {
+         tree cons = copy_node (init);
          CONSTRUCTOR_ELTS (init) = NULL;
-         code = build (MODIFY_EXPR, type, dest, init);
+         code = build (MODIFY_EXPR, type, dest, cons);
          code = build_stmt (EXPR_STMT, code);
          pcode = &TREE_CHAIN (code);
        }

patch.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit inicialization of v8qi miscompiled

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-12 19:16 -------
Patch here: <http://gcc.gnu.org/ml/gcc-patches/2005-01/msg00663.html>.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit initialization of v8qi miscompiled

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-01-14 23:46 -------
Subject: Bug 19263

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	jakub@gcc.gnu.org	2005-01-14 23:45:59

Modified files:
	gcc/cp         : ChangeLog typeck2.c 
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/g++.dg/init: vector1.C 

Log message:
	PR c++/19263
	* typeck2.c (split_nonconstant_init_1) <case VECTOR_TYPE>: Put a copy
	of CONSTRUCTOR's node into MODIFY_EXPR, as the original is modified.
	
	* g++.dg/init/vector1.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&r1=1.4575&r2=1.4576
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/typeck2.c.diff?cvsroot=gcc&r1=1.180&r2=1.181
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.4886&r2=1.4887
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/init/vector1.C.diff?cvsroot=gcc&r1=NONE&r2=1.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit initialization of v8qi miscompiled

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-01-14 23:51 -------
Subject: Bug 19263

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-3_4-branch
Changes by:	jakub@gcc.gnu.org	2005-01-14 23:51:39

Modified files:
	gcc/testsuite  : ChangeLog 
	gcc/cp         : ChangeLog typeck2.c 
Added files:
	gcc/testsuite/g++.dg/init: vector1.C 

Log message:
	PR c++/19263
	* typeck2.c (split_nonconstant_init_1) <case VECTOR_TYPE>: Put a copy
	of CONSTRUCTOR's node into MODIFY_EXPR, as the original is modified.
	Store code to *pcode.
	
	* g++.dg/init/vector1.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.3389.2.343&r2=1.3389.2.344
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.3892.2.189&r2=1.3892.2.190
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/typeck2.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.153.4.4&r2=1.153.4.5
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/init/vector1.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263

[Bug c++/19263] [3.4/4.0 regression]: wrong-code: explicit initialization of v8qi miscompiled

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-15 01:50 -------
Fixed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19263