diff options
| -rw-r--r-- | gcc/ChangeLog | 15 | ||||
| -rw-r--r-- | gcc/alias.c | 39 | ||||
| -rw-r--r-- | gcc/flow.c | 11 | ||||
| -rw-r--r-- | gcc/rtl.h | 1 |
4 files changed, 44 insertions, 22 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 6a17614..eb5e258 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,18 @@ +2003-09-12 Roger Sayle <roger@eyesopen.com> + + PR optimization/8967 + * alias.c (write_dependence_p): Modify to take an additional constp + argument that controls whether the UNCHANGING_RTX_P flags are used. + (anti_dependence, output_dependence): Adjust write_dependence_p + callers to pass this additional argument, to return the same result. + (unchanging_anti_dependence): New variant of anti_dependence that + ignores the UNCHANGING_RTX_P property on memory references. + * rtl.h (unchaning_anti_dependence): Prototype here. + * flow.c (init_propagate_block): Place fake constant mem writes on + the mem_set_list so that dead writes to const variables are deleted. + (insn_dead_p): Change anti_dependence to unchanging_anti_dependence. + (mark_used_regs): Likewise. + 2003-09-12 Richard Sandiford <rsandifo@redhat.com> * config/mcore/mcore-protos.h (mcore_r15_operand_p): Declare. diff --git a/gcc/alias.c b/gcc/alias.c index 3951fd6..f56820e 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -110,7 +110,7 @@ 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); +static int write_dependence_p (rtx, rtx, int, int); static int nonlocal_mentioned_p_1 (rtx *, void *); static int nonlocal_mentioned_p (rtx); @@ -2202,10 +2202,11 @@ 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. */ + (or, if WRITEP is nonzero, a write to) MEM. If CONSTP is non-zero, + honor the RTX_UNCHANGING_P flags on X and MEM. */ static int -write_dependence_p (rtx mem, rtx x, int writep) +write_dependence_p (rtx mem, rtx x, int writep, int constp) { rtx x_addr, mem_addr; rtx fixed_scalar; @@ -2224,15 +2225,18 @@ write_dependence_p (rtx mem, rtx x, int writep) if (DIFFERENT_ALIAS_SETS_P (x, mem)) return 0; - /* Unchanging memory can't conflict with non-unchanging memory. */ - if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (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; + /* 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; + } if (nonoverlapping_memrefs_p (x, mem)) return 0; @@ -2273,7 +2277,7 @@ write_dependence_p (rtx mem, rtx x, int writep) int anti_dependence (rtx mem, rtx x) { - return write_dependence_p (mem, x, /*writep=*/0); + return write_dependence_p (mem, x, /*writep=*/0, /*constp*/1); } /* Output dependence: X is written after store in MEM takes place. */ @@ -2281,7 +2285,16 @@ anti_dependence (rtx mem, rtx x) int output_dependence (rtx mem, rtx x) { - return write_dependence_p (mem, x, /*writep=*/1); + 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); } /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions @@ -1974,13 +1974,6 @@ init_propagate_block_info (basic_block bb, regset live, regset local_set, rtx mem = SET_DEST (set); rtx canon_mem = canon_rtx (mem); - /* This optimization is performed by faking a store to the - memory at the end of the block. This doesn't work for - unchanging memories because multiple stores to unchanging - memory is illegal and alias analysis doesn't consider it. */ - if (RTX_UNCHANGING_P (canon_mem)) - continue; - if (XEXP (canon_mem, 0) == frame_pointer_rtx || (GET_CODE (XEXP (canon_mem, 0)) == PLUS && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx @@ -2152,7 +2145,7 @@ insn_dead_p (struct propagate_block_info *pbi, rtx x, int call_ok, rtx_equal_p does not check the alias set or flags, we also must have the potential for them to conflict (anti_dependence). */ for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1)) - if (anti_dependence (r, XEXP (temp, 0))) + if (unchanging_anti_dependence (r, XEXP (temp, 0))) { rtx mem = XEXP (temp, 0); @@ -3730,7 +3723,7 @@ mark_used_regs (struct propagate_block_info *pbi, rtx x, rtx cond, rtx insn) while (temp) { next = XEXP (temp, 1); - if (anti_dependence (XEXP (temp, 0), x)) + if (unchanging_anti_dependence (XEXP (temp, 0), x)) { /* Splice temp out of the list. */ if (prev) @@ -2253,6 +2253,7 @@ extern int canon_true_dependence (rtx, enum machine_mode, rtx, rtx, extern int read_dependence (rtx, rtx); extern int anti_dependence (rtx, rtx); extern int output_dependence (rtx, rtx); +extern int unchanging_anti_dependence (rtx, rtx); extern void mark_constant_function (void); extern void init_alias_once (void); extern void init_alias_analysis (void); |