From f47e08d97a42b58e87bb4edaaa7889743c064b54 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Tue, 16 Feb 2010 10:01:51 +0000 Subject: [PATCH] alias.c (memrefs_conflict_p): Distinguish must-alias from don't know. 2010-02-16 Richard Guenther * 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 --- gcc/ChangeLog | 8 ++++++ gcc/alias.c | 73 ++++++++++++++++++++++++++++++--------------------- 2 files changed, 51 insertions(+), 30 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 5fad55c2da6..83879235ca0 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2010-02-16 Richard Guenther + + * 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 * params.def (PARAM_MAX_VARTRACK_SIZE): New. diff --git a/gcc/alias.c b/gcc/alias.c index 41a2f2318f7..71a34a29265 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -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 -- 2.30.2