We were not invalidating entries with a src that reads more than 1 register
when we find writes that overwrite any register read by entry->src after
the first. This leads to incorrect copy propagation because we re-use
entries from the ACP that have been partially invalidated.
---
.../drivers/dri/i965/brw_fs_copy_propagation.cpp | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
index 3e89a0d..89ba8c5 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -44,6 +44,7 @@ struct acp_entry : public exec_node {
fs_reg dst;
fs_reg src;
uint8_t regs_written;
+ uint8_t regs_read;
enum opcode opcode;
bool saturate;
};
@@ -775,8 +776,17 @@ fs_visitor::opt_copy_propagate_local(void *copy_prop_ctx,
bblock_t *block,
*/
for (int i = 0; i < ACP_HASH_SIZE; i++) {
foreach_in_list_safe(acp_entry, entry, &acp[i]) {
- if (inst->overwrites_reg(entry->src))
- entry->remove();
+ /* Make sure we kill the entry if this instructions overwrites
+ * _any_ of the registers that it reads
+ */
+ fs_reg tmp = entry->src;
+ for (int n = 0; n < entry->regs_read; n++) {
+ if (inst->overwrites_reg(tmp)) {
+ entry->remove();
+ break;
+ }
+ tmp.reg_offset++;
+ }
}
}
}
@@ -785,10 +795,11 @@ fs_visitor::opt_copy_propagate_local(void *copy_prop_ctx,
bblock_t *block,
* operand of another instruction, add it to the ACP.
*/
if (can_propagate_from(inst)) {
- acp_entry *entry = ralloc(copy_prop_ctx, acp_entry);
- entry->dst = inst->dst;
- entry->src = inst->src[0];
+ acp_entry *entry = ralloc(copy_prop_ctx, acp_entry);
+ entry->dst = inst->dst;
+ entry->src = inst->src[0];
entry->regs_written = inst->regs_written;
+ entry->regs_read = inst->regs_read(0);
entry->opcode = inst->opcode;
entry->saturate = inst->saturate;
acp[entry->dst.nr % ACP_HASH_SIZE].push_tail(entry);
@@ -804,6 +815,7 @@ fs_visitor::opt_copy_propagate_local(void *copy_prop_ctx,
bblock_t *block,
entry->dst.reg_offset = offset;
entry->src = inst->src[i];
entry->regs_written = regs_written;
+ entry->regs_read = inst->regs_read(i);
entry->opcode = inst->opcode;
if (!entry->dst.equals(inst->src[i])) {
acp[entry->dst.nr % ACP_HASH_SIZE].push_tail(entry);
--
2.1.4
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