This removes some odd code from true_dependence_1 and may_alias_p that
is not in write_dependence - namely special-casing of AND as
alias-everything (and the function doing the same named
aliases_everything_p). It also makes BLKmode SCRATCH handling
consistent between both and removes special casing of general
BLKmode handling from true_dependence_1. In both cases we only
dispatch to rtx_refs_may_alias_p after that which is not
confused by either.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
I'm leaving it for comments until next Monday.
Thanks,
Richard.
2012-06-06 Richard Guenther <rguent...@suse.de>
* alias.c (aliases_everything_p): Remove.
(DIFFERENT_ALIAS_SETS_P): Likewise.
(true_dependence_1): Use mems_in_disjoint_alias_sets_p directly.
Do not use aliases_everything_p or special-case ANDs. Do not
special-case BLKmode moves.
(may_alias_p): Likewise. Handle BLKmode similar like everywhere
- for SCATCH only.
Index: gcc/alias.c
===================================================================
*** gcc/alias.c (revision 188263)
--- gcc/alias.c (working copy)
*************** static rtx find_base_value (rtx);
*** 156,162 ****
static int mems_in_disjoint_alias_sets_p (const_rtx, const_rtx);
static int insert_subset_children (splay_tree_node, void*);
static alias_set_entry get_alias_set_entry (alias_set_type);
- static int aliases_everything_p (const_rtx);
static bool nonoverlapping_component_refs_p (const_tree, const_tree);
static tree decl_for_component_ref (tree);
static int write_dependence_p (const_rtx, const_rtx, int);
--- 156,161 ----
*************** static void memory_modified_1 (rtx, cons
*** 168,180 ****
/* Returns the size in bytes of the mode of X. */
#define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
- /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
- different alias sets. We ignore alias sets in functions making use
- of variable arguments because the va_arg macros on some systems are
- not legal ANSI C. */
- #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
- mems_in_disjoint_alias_sets_p (MEM1, MEM2)
-
/* Cap the number of passes we make over the insns propagating alias
information through set chains. 10 is a completely arbitrary choice. */
#define MAX_ALIAS_LOOP_PASSES 10
--- 167,172 ----
*************** read_dependence (const_rtx mem, const_rt
*** 2188,2207 ****
return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem);
}
- /* Returns nonzero if something about the mode or address format MEM1
- indicates that it might well alias *anything*. */
-
- static int
- aliases_everything_p (const_rtx mem)
- {
- if (GET_CODE (XEXP (mem, 0)) == AND)
- /* If the address is an AND, it's very hard to know at what it is
- actually pointing. */
- return 1;
-
- return 0;
- }
-
/* Return true if we can determine that the fields referenced cannot
overlap for any pair of objects. */
--- 2180,2185 ----
*************** true_dependence_1 (const_rtx mem, enum m
*** 2535,2559 ****
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, false))
return 0;
- if (aliases_everything_p (x))
- return 1;
-
- /* We cannot use aliases_everything_p to test MEM, since we must look
- at MEM_ADDR, rather than XEXP (mem, 0). */
- if (GET_CODE (mem_addr) == AND)
- return 1;
-
- /* ??? In true_dependence we also allow BLKmode to alias anything. Why
- don't we do this in anti_dependence and output_dependence? */
- if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
- return 1;
-
return rtx_refs_may_alias_p (x, mem, true);
}
--- 2513,2524 ----
SIZE_FOR_MODE (x), x_addr, 0)) != -1)
return ret;
! if (mems_in_disjoint_alias_sets_p (x, mem))
return 0;
if (nonoverlapping_memrefs_p (mem, x, false))
return 0;
return rtx_refs_may_alias_p (x, mem, true);
}
*************** may_alias_p (const_rtx mem, const_rtx x)
*** 2680,2689 ****
if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
return 1;
! /* ??? In true_dependence we also allow BLKmode to alias anything. */
! if (GET_MODE (mem) == BLKmode || GET_MODE (x) == BLKmode)
return 1;
-
if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
|| MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
return 1;
--- 2645,2656 ----
if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
return 1;
! /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
! This is used in epilogue deallocation functions. */
! if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
! return 1;
! if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
return 1;
if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
|| MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
return 1;
*************** may_alias_p (const_rtx mem, const_rtx x)
*** 2722,2735 ****
if (nonoverlapping_memrefs_p (mem, x, true))
return 0;
- if (aliases_everything_p (x))
- return 1;
-
- /* We cannot use aliases_everything_p to test MEM, since we must look
- at MEM_ADDR, rather than XEXP (mem, 0). */
- if (GET_CODE (mem_addr) == AND)
- return 1;
-
/* TBAA not valid for loop_invarint */
return rtx_refs_may_alias_p (x, mem, false);
}
--- 2689,2694 ----
