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ir3/cp: ir3: Prevent propagating shared regs out of loops harder 

We need to check the source of the copy, not the destination. That means
this we need to move this check inside the ifs, where we know that the
source is a copy.

Fixes: 590efd180b ("Prevent propagating shared regs out of loops")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14412>
This commit is contained in:
Connor Abbott 2022-01-05 19:45:55 +01:00 committed by Marge Bot
parent b6e5a03499
commit 09731fc79a
1 changed files with 22 additions and 11 deletions
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33
src/freedreno/ir3/ir3_cp.c
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@ -303,6 +303,22 @@ try_swap_mad_two_srcs(struct ir3_instruction *instr, unsigned new_flags)
return valid_swap;
}
/* Values that are uniform inside a loop can become divergent outside
* it if the loop has a divergent trip count. This means that we can't
* propagate a copy of a shared to non-shared register if it would
* make the shared reg's live range extend outside of its loop. Users
* outside the loop would see the value for the thread(s) that last
* exited the loop, rather than for their own thread.
*/
static bool
is_valid_shared_copy(struct ir3_instruction *dst_instr,
struct ir3_instruction *src_instr,
struct ir3_register *src_reg)
{
return !(src_reg->flags & IR3_REG_SHARED) ||
dst_instr->block->loop_id == src_instr->block->loop_id;
}
/**
* Handle cp for a given src register. This additionally handles
* the cases of collapsing immedate/const (which replace the src
@ -316,22 +332,14 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
{
struct ir3_instruction *src = ssa(reg);
/* Values that are uniform inside a loop can become divergent outside
* it if the loop has a divergent trip count. This means that we can't
* propagate a copy of a shared to non-shared register if it would
* make the shared reg's live range extend outside of its loop. Users
* outside the loop would see the value for the thread(s) that last
* exited the loop, rather than for their own thread.
*/
if ((src->dsts[0]->flags & IR3_REG_SHARED) &&
src->block->loop_id != instr->block->loop_id)
return false;
if (is_eligible_mov(src, instr, true)) {
/* simple case, no immed/const/relativ, only mov's w/ ssa src: */
struct ir3_register *src_reg = src->srcs[0];
unsigned new_flags = reg->flags;
if (!is_valid_shared_copy(instr, src, src_reg))
return false;
combine_flags(&new_flags, src);
if (ir3_valid_flags(instr, n, new_flags)) {
@ -357,6 +365,9 @@ reg_cp(struct ir3_cp_ctx *ctx, struct ir3_instruction *instr,
struct ir3_register *src_reg = src->srcs[0];
unsigned new_flags = reg->flags;
if (!is_valid_shared_copy(instr, src, src_reg))
return false;
if (src_reg->flags & IR3_REG_ARRAY)
return false;