Commit 74fe4eee authored by Michael Beck's avatar Michael Beck
Browse files

- allow implicit cast from two-complements signed/unsigned to be killed

- updated for new memory disambiguator

[r8520]
parent c16c91f2
......@@ -431,6 +431,23 @@ static void reduce_adr_usage(ir_node *ptr) {
}
} /* reduce_adr_usage */
/**
* Check, if an already existing value of mode old_mode can be converted
* into the needed one new_mode without loss.
*/
static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode) {
if (old_mode == new_mode)
return 1;
/* if both modes are two-complement ones, we can always convert the
Stored value into the needed one. */
if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
get_mode_arithmetic(old_mode) == irma_twos_complement &&
get_mode_arithmetic(new_mode) == irma_twos_complement)
return 1;
return 0;
} /* can_use_stored_value */
/**
* Follow the memory chain as long as there are only Loads
* and alias free Stores and try to replace current Load or Store
......@@ -459,7 +476,7 @@ static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
* is possible a = *(ir_type1 *)p; b = *(ir_type2 *)p ...
*/
if (get_irn_op(pred) == op_Store && get_Store_ptr(pred) == ptr &&
get_irn_mode(get_Store_value(pred)) == load_mode) {
can_use_stored_value(get_irn_mode(get_Store_value(pred)), load_mode)) {
/*
* a Load immediately after a Store -- a read after write.
* We may remove the Load, if both Load & Store does not have an exception handler
......@@ -477,6 +494,12 @@ static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
ir_node *value = get_Store_value(pred);
DBG_OPT_RAW(load, value);
/* add an convert if needed */
if (get_irn_mode(get_Store_value(pred)) != load_mode) {
value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
}
if (info->projs[pn_Load_M])
exchange(info->projs[pn_Load_M], mem);
......@@ -494,7 +517,7 @@ static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
return res | DF_CHANGED;
}
} else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
get_Load_mode(pred) == load_mode) {
can_use_stored_value(get_Load_mode(pred), load_mode)) {
/*
* a Load after a Load -- a read after read.
* We may remove the second Load, if it does not have an exception handler
......@@ -508,6 +531,13 @@ static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
DBG_OPT_RAR(load, pred);
if (pred_info->projs[pn_Load_res]) {
ir_node *value = pred_info->projs[pn_Load_res];
/* add an convert if needed */
if (get_Load_mode(pred) != load_mode) {
value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
}
/* we need a data proj from the previous load for this optimization */
if (info->projs[pn_Load_res])
exchange(info->projs[pn_Load_res], pred_info->projs[pn_Load_res]);
......@@ -545,7 +575,7 @@ static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
current_ir_graph,
get_Store_ptr(pred),
get_irn_mode(get_Store_value(pred)),
ptr, load_mode, opt_non_opt);
ptr, load_mode);
/* if the might be an alias, we cannot pass this Store */
if (rel != no_alias)
break;
......@@ -779,6 +809,15 @@ static unsigned optimize_load(ir_node *load)
return res;
} /* optimize_load */
/**
* Check whether a value of mode new_mode would completely overwrite a value
* of mode old_mode in memory.
*/
static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
{
return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
} /* is_completely_overwritten */
/**
* follow the memory chain as long as there are only Loads and alias free Stores.
*
......@@ -802,9 +841,12 @@ static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
* if the pointers are identical, they refer to the same object.
* This is only true in strong typed languages, not is C were the following
* is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
* However, if the mode that is written have a bigger or equal size the the old
* one, the old value is completely overwritten and can be killed ...
*/
if (get_irn_op(pred) == op_Store && get_Store_ptr(pred) == ptr &&
get_nodes_block(pred) == block && get_irn_mode(get_Store_value(pred)) == mode) {
get_nodes_block(pred) == block &&
is_completely_overwritten(get_irn_mode(get_Store_value(pred)), mode)) {
/*
* a Store after a Store in the same block -- a write after write.
* We may remove the first Store, if it does not have an exception handler.
......@@ -839,7 +881,7 @@ static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
current_ir_graph,
get_Store_ptr(pred),
get_irn_mode(get_Store_value(pred)),
ptr, mode, opt_non_opt);
ptr, mode);
/* if the might be an alias, we cannot pass this Store */
if (rel != no_alias)
break;
......@@ -1098,19 +1140,19 @@ static void do_load_store_optimize(ir_node *n, void *env) {
switch (get_irn_opcode(n)) {
case iro_Load:
wenv->changes |= optimize_load(n);
break;
case iro_Load:
wenv->changes |= optimize_load(n);
break;
case iro_Store:
wenv->changes |= optimize_store(n);
break;
case iro_Store:
wenv->changes |= optimize_store(n);
break;
case iro_Phi:
wenv->changes |= optimize_phi(n, wenv);
case iro_Phi:
wenv->changes |= optimize_phi(n, wenv);
default:
;
default:
;
}
} /* do_load_store_optimize */
......
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