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alias.c (memrefs_conflict_p): Distinguish must-alias from don't know.

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2010-02-16  Richard Guenther  <rguenther@suse.de>

	* alias.c (memrefs_conflict_p): Distinguish must-alias from
	don't know.
	(true_dependence): If memrefs_conflict_p computes must-alias
	trust it.  Move TBAA check after offset-based disambiguation.
	(canon_true_dependence): Likewise.

From-SVN: r156797
This commit is contained in:
Richard Guenther 2010-02-16 10:01:51 +00:00 committed by Richard Biener
parent 7bc19392e5
commit f47e08d97a
2 changed files with 51 additions and 30 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2010-02-16 Richard Guenther <rguenther@suse.de>
* alias.c (memrefs_conflict_p): Distinguish must-alias from
don't know.
(true_dependence): If memrefs_conflict_p computes must-alias
trust it. Move TBAA check after offset-based disambiguation.
(canon_true_dependence): Likewise.
2010-02-16 Alexandre Oliva <aoliva@redhat.com>
* params.def (PARAM_MAX_VARTRACK_SIZE): New.

73
gcc/alias.c
View File

@ -1759,8 +1759,12 @@ addr_side_effect_eval (rtx addr, int size, int n_refs)
return addr;
}
/* Return nonzero if X and Y (memory addresses) could reference the
same location in memory. C is an offset accumulator. When
/* Return one if X and Y (memory addresses) reference the
same location in memory or if the references overlap.
Return zero if they do not overlap, else return
minus one in which case they still might reference the same location.
C is an offset accumulator. When
C is nonzero, we are testing aliases between X and Y + C.
XSIZE is the size in bytes of the X reference,
similarly YSIZE is the size in bytes for Y.
@ -1775,7 +1779,11 @@ addr_side_effect_eval (rtx addr, int size, int n_refs)
align memory references, as is done on the Alpha.
Nice to notice that varying addresses cannot conflict with fp if no
local variables had their addresses taken, but that's too hard now. */
local variables had their addresses taken, but that's too hard now.
??? Contrary to the tree alias oracle this does not return
one for X + non-constant and Y + non-constant when X and Y are equal.
If that is fixed the TBAA hack for union type-punning can be removed. */
static int
memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
@ -1841,7 +1849,7 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
else if (CONST_INT_P (y1))
return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
return 1;
return -1;
}
else if (CONST_INT_P (x1))
return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
@ -1856,7 +1864,7 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
if (CONST_INT_P (y1))
return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
else
return 1;
return -1;
}
if (GET_CODE (x) == GET_CODE (y))
@ -1871,7 +1879,7 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
rtx x1 = canon_rtx (XEXP (x, 1));
rtx y1 = canon_rtx (XEXP (y, 1));
if (! rtx_equal_for_memref_p (x1, y1))
return 1;
return -1;
x0 = canon_rtx (XEXP (x, 0));
y0 = canon_rtx (XEXP (y, 0));
if (rtx_equal_for_memref_p (x0, y0))
@ -1880,7 +1888,7 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
/* Can't properly adjust our sizes. */
if (!CONST_INT_P (x1))
return 1;
return -1;
xsize /= INTVAL (x1);
ysize /= INTVAL (x1);
c /= INTVAL (x1);
@ -1939,9 +1947,10 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
|| (rtx_equal_for_memref_p (x, y)
&& ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
return 1;
return -1;
}
return 1;
return -1;
}
/* Functions to compute memory dependencies.
@ -2294,6 +2303,7 @@ true_dependence (const_rtx mem, enum machine_mode mem_mode, const_rtx x,
{
rtx x_addr, mem_addr;
rtx base;
int ret;
if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
return 1;
@ -2308,18 +2318,12 @@ true_dependence (const_rtx mem, enum machine_mode mem_mode, const_rtx x,
|| MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
return 1;
if (DIFFERENT_ALIAS_SETS_P (x, mem))
return 0;
/* Read-only memory is by definition never modified, and therefore can't
conflict with anything. We don't expect to find read-only set on MEM,
but stupid user tricks can produce them, so don't die. */
if (MEM_READONLY_P (x))
return 0;
if (nonoverlapping_memrefs_p (mem, x))
return 0;
/* If we have MEMs refering to different address spaces (which can
potentially overlap), we cannot easily tell from the addresses
whether the references overlap. */
@ -2344,8 +2348,14 @@ true_dependence (const_rtx mem, enum machine_mode mem_mode, const_rtx x,
x_addr = canon_rtx (x_addr);
mem_addr = canon_rtx (mem_addr);
if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
SIZE_FOR_MODE (x), x_addr, 0))
if ((ret = memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
SIZE_FOR_MODE (x), x_addr, 0)) != -1)
return ret;
if (DIFFERENT_ALIAS_SETS_P (x, mem))
return 0;
if (nonoverlapping_memrefs_p (mem, x))
return 0;
if (aliases_everything_p (x))
@ -2378,6 +2388,8 @@ int
canon_true_dependence (const_rtx mem, enum machine_mode mem_mode, rtx mem_addr,
const_rtx x, rtx x_addr, bool (*varies) (const_rtx, bool))
{
int ret;
if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
return 1;
@ -2391,18 +2403,12 @@ canon_true_dependence (const_rtx mem, enum machine_mode mem_mode, rtx mem_addr,
|| MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
return 1;
if (DIFFERENT_ALIAS_SETS_P (x, mem))
return 0;
/* Read-only memory is by definition never modified, and therefore can't
conflict with anything. We don't expect to find read-only set on MEM,
but stupid user tricks can produce them, so don't die. */
if (MEM_READONLY_P (x))
return 0;
if (nonoverlapping_memrefs_p (x, mem))
return 0;
/* If we have MEMs refering to different address spaces (which can
potentially overlap), we cannot easily tell from the addresses
whether the references overlap. */
@ -2416,8 +2422,14 @@ canon_true_dependence (const_rtx mem, enum machine_mode mem_mode, rtx mem_addr,
return 0;
x_addr = canon_rtx (x_addr);
if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
SIZE_FOR_MODE (x), x_addr, 0))
if ((ret = memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
SIZE_FOR_MODE (x), x_addr, 0)) != -1)
return ret;
if (DIFFERENT_ALIAS_SETS_P (x, mem))
return 0;
if (nonoverlapping_memrefs_p (x, mem))
return 0;
if (aliases_everything_p (x))
@ -2448,6 +2460,7 @@ write_dependence_p (const_rtx mem, const_rtx x, int writep)
rtx x_addr, mem_addr;
const_rtx fixed_scalar;
rtx base;
int ret;
if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
return 1;
@ -2466,9 +2479,6 @@ write_dependence_p (const_rtx mem, const_rtx x, int writep)
if (!writep && MEM_READONLY_P (mem))
return 0;
if (nonoverlapping_memrefs_p (x, mem))
return 0;
/* If we have MEMs refering to different address spaces (which can
potentially overlap), we cannot easily tell from the addresses
whether the references overlap. */
@ -2494,8 +2504,11 @@ write_dependence_p (const_rtx mem, const_rtx x, int writep)
x_addr = canon_rtx (x_addr);
mem_addr = canon_rtx (mem_addr);
if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
SIZE_FOR_MODE (x), x_addr, 0))
if ((ret = memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
SIZE_FOR_MODE (x), x_addr, 0)) != -1)
return ret;
if (nonoverlapping_memrefs_p (x, mem))
return 0;
fixed_scalar