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when eliminating stores, don't look for an exact match, just look to 

see if any combination of entries covers the entire access range

moved partial invalidation check to lse_get_available itself, making
lse_erase_available's logic more straight forward
This commit is contained in:
Anthony Pesch 2017-08-18 00:26:16 -04:00
parent f6827af92c
commit 9092471120
1 changed files with 32 additions and 24 deletions
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56
src/jit/passes/load_store_elimination_pass.c
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@ -31,19 +31,6 @@ static void lse_erase_available(struct lse *lse, int offset, int size) {
int end = offset + size - 1;
CHECK_LT(end, IR_MAX_CONTEXT);
/* if the invalidation range intersects with an entry, merge that entry into
the invalidation range */
struct lse_entry *begin_entry = &lse->available[begin];
struct lse_entry *end_entry = &lse->available[end];
if (begin_entry->token == lse->token) {
begin = begin_entry->offset;
}
if (end_entry->token == lse->token) {
end = end_entry->offset + ir_type_size(end_entry->value->type) - 1;
}
for (; begin <= end; begin++) {
struct lse_entry *entry = &lse->available[begin];
entry->token = 0;
@ -52,16 +39,13 @@ static void lse_erase_available(struct lse *lse, int offset, int size) {
}
}
static void lse_set_available(struct lse *lse, int offset, struct ir_value *v) {
static void lse_set_available(struct lse *lse, int offset,
struct ir_value *v) {
int size = ir_type_size(v->type);
int begin = offset;
int end = offset + size - 1;
CHECK_LT(end, IR_MAX_CONTEXT);
lse_erase_available(lse, offset, size);
/* add entries for the entire range to aid in invalidation. only the initial
entry where offset == entry.offset is valid for reuse */
for (; begin <= end; begin++) {
struct lse_entry *entry = &lse->available[begin];
entry->token = lse->token;
@ -87,9 +71,35 @@ static struct ir_value *lse_get_available(struct lse *lse, int offset) {
return NULL;
}
/* validate the entry hasn't been partially invalidated */
int size = ir_type_size(entry->value->type);
for (int i = 0; i < size; i++) {
struct lse_entry *entry2 = &lse->available[offset + i];
if (entry2->value != entry->value) {
return NULL;
}
}
return entry->value;
}
static int lse_test_available(struct lse *lse, int offset, int size) {
int begin = offset;
int end = offset + size - 1;
CHECK_LT(end, IR_MAX_CONTEXT);
/* test if any combination of entries cover the entire range */
for (; begin <= end; begin++) {
struct lse_entry *entry = &lse->available[begin];
if (entry->token != lse->token) {
return 0;
}
}
return 1;
}
static void lse_eliminate_loads(struct lse *lse, struct ir *ir,
struct ir_block *block) {
lse_clear_available(lse);
@ -143,14 +153,12 @@ static void lse_eliminate_stores(struct lse *lse, struct ir *ir,
lse_erase_available(lse, offset, size);
} else if (instr->op == OP_STORE_CONTEXT) {
/* if subsequent stores have been made for this offset that would
overwrite it completely, mark instruction as dead */
/* if subsequent stores overwrite this completely, kill it */
int offset = instr->arg[0]->i32;
struct ir_value *existing = lse_get_available(lse, offset);
int existing_size = existing ? ir_type_size(existing->type) : 0;
int store_size = ir_type_size(instr->arg[1]->type);
int size = ir_type_size(instr->arg[1]->type);
int overwritten = lse_test_available(lse, offset, size);
if (existing_size >= store_size) {
if (overwritten) {
ir_remove_instr(ir, instr);
STAT_stores_removed++;
continue;