c/3037: ARM port: Wrong flow info after reload

[denisc@overta.ru]

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>Number:         3037
>Category:       c
>Synopsis:       ARM port: Wrong flow info after reload
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          ice-on-legal-code
>Submitter-Id:   net
>Arrival-Date:   Sat Jun 02 02:26:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Denis
>Release:        3.0 20010525 (prerelease)
>Organization:
None
>Environment:
System: Linux localhost 2.3.2 #6 ðÔÎ ïËÔ 13 20:07:05 MSD 2000 i586 unknown
Architecture: i586

	
host: i586-pc-linux-gnu
build: i586-pc-linux-gnu
target: arm-elf-linux-gnu
configured with: /root/d/cvs/gcc-3.0/configure --target=arm-elf-linux --with-newlib --enable-languages=c : (reconfigured) /root/d/cvs/gcc-3.0/configure --target=arm-elf-linux --with-newlib --enable-languages=c --without-threads : (reconfigured) /root/d/cvs/gcc-3.0/configure --target=arm-elf-linux --with-newlib --enable-languages=c --disable-threads : (reconfigured) /root/d/cvs/gcc-3.0/configure --target=arm-elf-linux --with-newlib --enable-languages=c --disable-threads --disable-shared
>Description:

As I understand the ARM port have a `(define_expand "epilogue" ...)'
And this `define_expand' don't emit the moves on RTL level for restoring
a call-saved registers.

While `update_life_info' executed after reload the `mark_regs_live_at_end'
mark all registers used by the epilogue as being live at the end of
the function and don't unmark it because RTL version of epilogue
havn't a moves.

	
>How-To-Repeat:

typedef struct {
  int e;
  double d[40];
} mp_no;

typedef union { int i[2]; double d; } number;

static const number
     radix = {{0x41700000, 0x00000000} },
     zero = {{0x00000000, 0x00000000} },
     one = {{0x3ff00000, 0x00000000} },
     mone = {{0xbff00000, 0x00000000} };

void __dbl_mp(double x, mp_no *y, int p)
{

  int i,n;
  double u;


  if (x == zero.d)
      return;
  else if (x > zero.d)
      y->d[0] = one.d;
  else
    {
      y->d[0] = mone.d;
      x=-x;
    }
    
  for ( ; x < one.d; y->e -= one.d)
    x *= radix.d;

}
	
>Fix:
	

One of:
1. emit a RTL moves in epilogue;
2. remove `(define_expand "epilogue" ...)' (Why it's needed ?)
3. Fix flow.c:mark_regs_live_at_end

Fragment from flow.c:mark_regs_live_at_end:

  /* Mark all global registers, and all registers used by the epilogue
     as being live at the end of the function since they may be
     referenced by our caller.  */
  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    if (global_regs[i] || EPILOGUE_USES (i))
      SET_REGNO_REG_SET (set, i);

  if (HAVE_epilogue && reload_completed) /* ---- May be fixed here ? */
    {
      /* Mark all call-saved registers that we actually used.  */
      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
	if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
	  SET_REGNO_REG_SET (set, i);
    }

>Release-Note:
>Audit-Trail:
>Unformatted: