[Bug target/40668] New: 64-bit sparc miscompiles memcpy of argument inside switch

[Bug target/40668] New: 64-bit sparc miscompiles memcpy of argument inside switch

[blp at cs dot stanford dot edu]

The following program should print 12345678.  When it is built with "-O2 -m64"
or "-O3 -fno-inline -m64" on sparc, it instead prints 0.

I ran this test with the command "/opt/cfarm/release/4.4.0/bin/gcc -fno-inline
-O3 -m64 -g combined.c" on gcc62 in the GCC compile farm.

----------------------------------------------------------------------

"/opt/cfarm/release/4.4.0/bin/gcc -v" prints:

    Using built-in specs.
    Target: sparc64-unknown-linux-gnu
    Configured with: ../gcc-4.4.0/configure
--enable-languages=c,c++,fortran,ada --prefix=/opt/cfarm/release/4.4.0
--enable-__cxa_atexit --enable-threads=posix --disable-nls
--with-mpfr=/opt/cfarm/mpfr-2.4.1 --with-gmp=/opt/cfarm/gmp-4.2.4 --with-cpu=v8
    Thread model: posix
    gcc version 4.4.0 (GCC) 

----------------------------------------------------------------------

#include <stdint.h>
#include <stdio.h>
#include <string.h>

/* Stores 32-bit unsigned integer X at P,
   which need not be aligned. */
static void
put_uint32 (uint32_t x, void *p)
{
  memcpy (p, &x, sizeof x);
}

void
store_12345678 (int type, void *number)
{
  switch (type)
    {
    case 1:
      printf ("got here\n");
      put_uint32 (0x12345678, number);
      break;

    case 7:
      put_uint32 (0, number);
      break;
    case 8:
      put_uint32 (0, number);
      break;
    case 9:
      put_uint32 (0, number);
      break;
    }
}

int
main (void)
{
  uint32_t x;
  store_12345678 (1, &x);
  printf ("%x\n", (unsigned int) x);
  return 0;
}


-- 
           Summary: 64-bit sparc miscompiles memcpy of argument inside
                    switch
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: blp at cs dot stanford dot edu
 GCC build triplet: sparc64-unknown-linux-gnu
  GCC host triplet: sparc64-unknown-linux-gnu
GCC target triplet: sparc64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[blp at cs dot stanford dot edu]

------- Comment #2 from blp at cs dot stanford dot edu  2009-07-07 05:58 -------
Created an attachment (id=18148)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18148&action=view)
test program (before preprocessing)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[blp at cs dot stanford dot edu]

------- Comment #1 from blp at cs dot stanford dot edu  2009-07-07 05:57 -------
Created an attachment (id=18147)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18147&action=view)
preprocessed test input


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[mikpe at it dot uu dot se]

------- Comment #3 from mikpe at it dot uu dot se  2009-07-07 11:35 -------
Confirmed, with gcc-4.3-20090705 it works, with gcc-4.4-20090630 it fails.
Compiling with -S and comparing the .s files it looks like 4.4 completely
mis-schedules the code for put_uint32:

put_uint32:
        .register       %g2, #scratch
        .register       %g3, #scratch
        ldub    [%sp+2175], %g1
        ldub    [%sp+2176], %g3
        ldub    [%sp+2177], %g2
        ldub    [%sp+2178], %g4
        st      %o0, [%sp+2175]
        stb     %g4, [%o1+3]
        stb     %g1, [%o1]
        stb     %g3, [%o1+1]
        jmp     %o7+8
         stb    %g2, [%o1+2]

Notice how the store of %o0 to the four bytes at %sp+2175 comes after the
corresponding byte loads, so %g1 to %g4 are loaded with garbage, likely zeroes.

In contrast, gcc-4.3 generates the store before the loads:

put_uint32:
        .register       %g2, #scratch
        .register       %g3, #scratch
        st      %o0, [%sp+2175]
        ldub    [%sp+2176], %g3
        ldub    [%sp+2177], %g4
        ldub    [%sp+2178], %g2
        ldub    [%sp+2175], %g1
        stb     %g2, [%o1+3]
        stb     %g1, [%o1]
        stb     %g3, [%o1+1]
        jmp     %o7+8
         stb    %g4, [%o1+2]


-- 

mikpe at it dot uu dot se changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mikpe at it dot uu dot se


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[mikpe at it dot uu dot se]

------- Comment #4 from mikpe at it dot uu dot se  2009-07-07 16:28 -------
A reghunt identified Jakub's (added to cc: list) r142481 (PR38367 fix) as the
source of this regression.


-- 

mikpe at it dot uu dot se changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2009-07-07 19:05 -------
Created an attachment (id=18151)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18151&action=view)
gcc44-pr40668.patch

Untested patch that fixes this testcase.  I believe my commit was correct, but
apparently it can be modified later on without adjusting MEM_OFFSET.
I don't have a working SPARC box around ATM, so I can't bootstrap/regtest it
there.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[mikpe at it dot uu dot se]

------- Comment #6 from mikpe at it dot uu dot se  2009-07-07 23:10 -------
(In reply to comment #5)
> Created an attachment (id=18151)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18151&action=view) [edit]
> gcc44-pr40668.patch
> 
> Untested patch that fixes this testcase.

Thanks. This fixes the issue in a cross-compiler to sparc64-linux. I'm
currently bootstrapping 4.4-20090630 plus this patch on an Ultra5, I'll follow
up once that's complete (it will take quite a while).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[mikpe at it dot uu dot se]

------- Comment #7 from mikpe at it dot uu dot se  2009-07-08 16:43 -------
4.4-20090630 plus this fix bootstrapped fine, fixed the test case, built a
working 2.6.31-rc2 Linux kernel, and built a working Erlang VM.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[blp at cs dot stanford dot edu]

------- Comment #8 from blp at cs dot stanford dot edu  2009-07-08 17:30 -------
Wow, that's amazingly fast turnaround.  Thanks so much guys!


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[jakub at gcc dot gnu dot org]

------- Comment #9 from jakub at gcc dot gnu dot org  2009-07-11 09:23 -------
Subject: Bug 40668

Author: jakub
Date: Sat Jul 11 09:23:32 2009
New Revision: 149511

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149511
Log:
        PR target/40668
        * function.c (assign_parm_setup_stack): Adjust
        MEM_OFFSET (data->stack_parm) if promoted_mode is different
        from nominal_mode on big endian.

        * gcc.c-torture/execute/pr40668.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr40668.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/function.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[jakub at gcc dot gnu dot org]

------- Comment #10 from jakub at gcc dot gnu dot org  2009-07-11 09:26 -------
Subject: Bug 40668

Author: jakub
Date: Sat Jul 11 09:26:23 2009
New Revision: 149512

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149512
Log:
        PR target/40668
        * function.c (assign_parm_setup_stack): Adjust
        MEM_OFFSET (data->stack_parm) if promoted_mode is different
        from nominal_mode on big endian.

        * gcc.c-torture/execute/pr40668.c: New test.

Added:
    branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/execute/pr40668.c
Modified:
    branches/gcc-4_4-branch/gcc/ChangeLog
    branches/gcc-4_4-branch/gcc/function.c
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668

[Bug target/40668] 64-bit sparc miscompiles memcpy of argument inside switch

[ebotcazou at gcc dot gnu dot org]

------- Comment #11 from ebotcazou at gcc dot gnu dot org  2010-09-20 21:46 -------
By Jakub.


-- 

ebotcazou at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.4.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40668