[Bug middle-end/23775] New: 4.1: wrong code in argument passing

[Bug middle-end/23775] New: 4.1: wrong code in argument passing

[gcc-bugzilla at gcc dot gnu dot org]

On a i686 platform, the example below is miscompiled with -O1.
I expect this program to print -0.96.  Here's what it actually does:

$ g++ -O1 -o y y.cc
$ ./y
-1.288766
$ g++  -o y y.cc
$ ./y
-0.960000
$

The value that the optimized version prints is actually different
on each run of the program.

Here's the generated code for main(), 

.globl main
	.type	main, @function
main:
	pushl	%ebp
	movl	%esp, %ebp
	subl	$24, %esp
	movl	%ebx, -8(%ebp)
	movl	%esi, -4(%ebp)
	andl	$-16, %esp
	subl	$16, %esp
	movl	$0, 12(%esp)
	movl	8(%esp), %ebx    ; this seems to load ebx with garbage???
	movl	12(%esp), %esi
	fldz
	fstl	8(%esp)
	fstpl	(%esp)
	call	_Z8x_from_zdd
	fstpl	4(%esp)
	movl	%ebx, 8(%esp)    ; this clobbers half of the arg with
                                 ; the garbage
	movl	%esi, 12(%esp)
	movl	$0, (%esp)
	call	_Z17local_to_trflocalidi
	movl	$0, %eax
	movl	-8(%ebp), %ebx
	movl	-4(%ebp), %esi
	movl	%ebp, %esp
	popl	%ebp
	ret

It looks to me like the error occurs during RTL generation.
Here's the tree dump from the t87.final_cleanup file (slightly trimmed):

void local_to_trflocal(int, double, int) (D.1741, x_loc, D.1743)
{
<bb 0>:
  printf (&"%f\n"[0], x_loc);
  return;
}

double x_from_z(double, double) (pitch, stereo)
{
<bb 0>:
  return -9.59999999999999964472863211994990706443786621094e-1 / cos (stereo);
}

int main() ()
{
<bb 0>:
  local_to_trflocal (0, x_from_z (0.0, 0.0), 0);
  return 0;
}


But in the 00.expand file, here's the sequence leading
to the local_to_trflocal() call:

(insn 27 26 28 1 (set (mem/i:DF (plus:SI (reg/f:SI 56 virtual-outgoing-args)
                (const_int 4 [0x4])) [0 S8 A32])
        (reg:DF 71)) -1 (nil)
    (nil))

(insn 28 27 29 1 (set (mem:DI (plus:SI (reg/f:SI 56 virtual-outgoing-args)
                (const_int 8 [0x8])) [0 S8 A8])
        (reg:DI 68)) -1 (nil)
    (nil))

(insn 29 28 30 1 (set (mem:SI (reg/f:SI 56 virtual-outgoing-args) [0 S4 A32])
        (const_int 0 [0x0])) -1 (nil)
    (nil))

(call_insn 30 29 31 1 (call (mem:QI (symbol_ref:SI ("_Z17local_to_trflocalidi") [flags 0x3] <function_decl 0xb7f0df80 local_to_trflocal>) [0 S1 A8])
        (const_int 16 [0x10])) -1 (nil)
    (nil)
    (nil))


Reg 71 here is the return value from x_from_z.
I don't know where the DI store to v-o-a+8 is coming from...

Environment:
System: Linux karma 2.6.12.1sss #2 Thu Jul 7 00:28:21 EDT 2005 i686 i686 i386 GNU/Linux
Architecture: i686

	<machine, os, target, libraries (multiple lines)>
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: /home/sss/gcc/gcc/configure --prefix=/usr/local/gcc --enable-threads=posix --enable-long-long --enable-languages=c,c++,f95

How-To-Repeat:

Compile with -O1

-----------------------------------------------------
//g++ -O1 -g -o y y.cc 

extern "C" double cos(double);
extern "C" int printf (...);


double x_from_z(double pitch=0, double stereo=0)
{
  return -0.96/cos(stereo);
}

void local_to_trflocal(int, double x_loc, int=0)
{
  printf ("%f\n", x_loc);
}


int main()
{
  local_to_trflocal(0, x_from_z());
  return 0;
}

-----------------------------------------------------
------- Additional Comments From snyder at fnal dot gov  2005-09-08 02:31 -------
Fix:
	<how to correct or work around the problem, if known (multiple lines)>

-- 
           Summary: 4.1: wrong code in argument passing
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: snyder at fnal dot gov
                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=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-08 05:52 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|middle-end                  |target
     Ever Confirmed|                            |1
  GCC build triplet|i686-pc-linux-gnu           |
   GCC host triplet|i686-pc-linux-gnu           |
           Keywords|                            |wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2005-09-08 05:52:53
               date|                            |
            Summary|4.1: wrong code in argument |[4.1 Regression] wrong code
                   |passing                     |in argument passing
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[rguenth at gcc dot gnu dot org]

------- Additional Comments From rguenth at gcc dot gnu dot org  2005-09-08 09:08 -------
Reduced testcase:

extern "C" double cos(double);
extern "C" void abort(void);

double x_from_z(double pitch=0, double stereo=0); // __attribute__((const));
double x_from_z(double pitch, double stereo)
{
  return 1.0/cos(stereo);
}

void local_to_trflocal(int, double x_loc, int=0)
{
  if (x_loc != 1.0)
    abort ();
}

int main()
{
  local_to_trflocal(0, x_from_z());
  return 0;
}

Code is ok if you declare x_from_z const.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-08 12:46 -------
And here is a C testcase:
double cos(double);
void abort(void);

double x_from_z(double pitch, double stereo); // __attribute__((const));
double x_from_z(double pitch, double stereo)
{
  return 1.0/cos(stereo);
}

void local_to_trflocal(int b, double x_loc, int a)
{
  if (x_loc != 1.0)
    abort ();
}

int main()
{
  local_to_trflocal(0, x_from_z(0,0),0);
  return 0;
}

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[jakub at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-09-08 05:52:53         |2005-09-08 16:43:23
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[jakub at gcc dot gnu dot org]

------- Additional Comments From jakub at gcc dot gnu dot org  2005-09-09 17:43 -------
The difference between 4.0 and HEAD is the expr.c hunk of
http://gcc.gnu.org/ml/gcc-patches/2005-07/msg02021.html
If Paolo's reversion of that:
http://gcc.gnu.org/ml/gcc-patches/2005-09/msg00589.html
makes it in, the testcase will pass again.

The real problem is I think that when calls.c decides to save stack area
under an argument for the inner expand_call, but that argument partially overlaps
with the result of the call, we save/restore the argument with the inner
expand_call's argument mode and don't just limit to the actual bytes that
have already been initialized.  So we read some uninitialized bits from the
stack and overwrite with them the computed argument.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[pinskia at gcc dot gnu dot org]

------- Comment #11 from pinskia at gcc dot gnu dot org  2005-11-16 21:32 -------
And for the realy record this was fixed by the patch which fixed PR 24003 also.


-- 

pinskia at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[steven at gcc dot gnu dot org]

------- Comment #10 from steven at gcc dot gnu dot org  2005-11-04 22:56 -------
For the record, Jakub has apparently dropped this bug from his list to put this
bug back into unassigned state.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[jakub at gcc dot gnu dot org]

-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu dot
                   |                            |org
         AssignedTo|jakub at gcc dot gnu dot org|unassigned at gcc dot gnu
                   |                            |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[steven at gcc dot gnu dot org]

------- Comment #9 from steven at gcc dot gnu dot org  2005-11-03 21:00 -------
Jakub, ping!
What's up with this one?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[mmitchel at gcc dot gnu dot org]

------- Comment #8 from mmitchel at gcc dot gnu dot org  2005-10-31 05:41 -------
Yup, this is a showstoppper.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[pluto at agmk dot net]

------- Comment #7 from pluto at agmk dot net  2005-10-17 19:01 -------
both testcases works for me 4.1.0-20051005.
i have applied patches for: PR7776, PR20297, PR22533, PR23948, PR19505,
PR20606/PR24069.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |critical


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775

[Bug target/23775] [4.1 Regression] wrong code in argument passing

[pinskia at gcc dot gnu dot org]

------- Comment #6 from pinskia at gcc dot gnu dot org  2005-10-16 21:51 -------
Any news on getting this fixed?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23775