diff options
Diffstat (limited to 'gcc/alias.c')
| -rw-r--r-- | gcc/alias.c | 62 |
1 files changed, 16 insertions, 46 deletions
diff --git a/gcc/alias.c b/gcc/alias.c index 7200fff..57bc38d 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -113,7 +113,7 @@ static bool nonoverlapping_component_refs_p (tree, tree); static tree decl_for_component_ref (tree); static rtx adjust_offset_for_component_ref (tree, rtx); static int nonoverlapping_memrefs_p (rtx, rtx); -static int write_dependence_p (rtx, rtx, int, int); +static int write_dependence_p (rtx, rtx, int); static int nonlocal_mentioned_p_1 (rtx *, void *); static int nonlocal_mentioned_p (rtx); @@ -2173,17 +2173,10 @@ true_dependence (rtx mem, enum machine_mode mem_mode, rtx x, if (DIFFERENT_ALIAS_SETS_P (x, mem)) return 0; - /* Unchanging memory can't conflict with non-unchanging memory. - A non-unchanging read can conflict with a non-unchanging write. - An unchanging read can conflict with an unchanging write since - there may be a single store to this address to initialize it. - Note that an unchanging store can conflict with a non-unchanging read - since we have to make conservative assumptions when we have a - record with readonly fields and we are copying the whole thing. - Just fall through to the code below to resolve potential conflicts. - This won't handle all cases optimally, but the possible performance - loss should be negligible. */ - if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem)) + /* 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 abort. */ + if (MEM_READONLY_P (x)) return 0; if (nonoverlapping_memrefs_p (mem, x)) @@ -2253,14 +2246,10 @@ canon_true_dependence (rtx mem, enum machine_mode mem_mode, rtx mem_addr, if (DIFFERENT_ALIAS_SETS_P (x, mem)) return 0; - /* If X is an unchanging read, then it can't possibly conflict with any - non-unchanging store. It may conflict with an unchanging write though, - because there may be a single store to this address to initialize it. - Just fall through to the code below to resolve the case where we have - both an unchanging read and an unchanging write. This won't handle all - cases optimally, but the possible performance loss should be - negligible. */ - if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem)) + /* 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 abort. */ + if (MEM_READONLY_P (x)) return 0; if (nonoverlapping_memrefs_p (x, mem)) @@ -2294,11 +2283,10 @@ canon_true_dependence (rtx mem, enum machine_mode mem_mode, rtx mem_addr, } /* Returns nonzero if a write to X might alias a previous read from - (or, if WRITEP is nonzero, a write to) MEM. If CONSTP is nonzero, - honor the RTX_UNCHANGING_P flags on X and MEM. */ + (or, if WRITEP is nonzero, a write to) MEM. */ static int -write_dependence_p (rtx mem, rtx x, int writep, int constp) +write_dependence_p (rtx mem, rtx x, int writep) { rtx x_addr, mem_addr; rtx fixed_scalar; @@ -2317,18 +2305,9 @@ write_dependence_p (rtx mem, rtx x, int writep, int constp) if (DIFFERENT_ALIAS_SETS_P (x, mem)) return 0; - if (constp) - { - /* Unchanging memory can't conflict with non-unchanging memory. */ - if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (mem)) - return 0; - - /* If MEM is an unchanging read, then it can't possibly conflict with - the store to X, because there is at most one store to MEM, and it - must have occurred somewhere before MEM. */ - if (! writep && RTX_UNCHANGING_P (mem)) - return 0; - } + /* A read from read-only memory can't conflict with read-write memory. */ + if (!writep && MEM_READONLY_P (mem)) + return 0; if (nonoverlapping_memrefs_p (x, mem)) return 0; @@ -2369,7 +2348,7 @@ write_dependence_p (rtx mem, rtx x, int writep, int constp) int anti_dependence (rtx mem, rtx x) { - return write_dependence_p (mem, x, /*writep=*/0, /*constp*/1); + return write_dependence_p (mem, x, /*writep=*/0); } /* Output dependence: X is written after store in MEM takes place. */ @@ -2377,16 +2356,7 @@ anti_dependence (rtx mem, rtx x) int output_dependence (rtx mem, rtx x) { - return write_dependence_p (mem, x, /*writep=*/1, /*constp*/1); -} - -/* Unchanging anti dependence: Like anti_dependence but ignores - the UNCHANGING_RTX_P property on const variable references. */ - -int -unchanging_anti_dependence (rtx mem, rtx x) -{ - return write_dependence_p (mem, x, /*writep=*/0, /*constp*/0); + return write_dependence_p (mem, x, /*writep=*/1); } /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions |