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freedreno/ir3: Don't try re-swapping cat3 srcs

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This can lead us to endless loops of "progress".. Note fixes commit
commit really just exposed an existing problem.

Fixes: 9c9e8c3349 ("nir: Reorder ffma and fsub combining")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6133
Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15336>
This commit is contained in:
Rob Clark 2022-03-10 20:46:23 -08:00 • committed by Marge Bot
parent fa59556e1a
commit 05d6877235
2 changed files with 20 additions and 3 deletions
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1
src/freedreno/ir3/ir3.h
View file

@ -361,6 +361,7 @@ struct ir3_instruction {
IR3_SRC_PACKED_LOW = 0,
IR3_SRC_PACKED_HIGH = 1,
} packed;
bool swapped;
} cat3;
struct {
unsigned samp, tex;

22
src/freedreno/ir3/ir3_cp.c
View file

@ -276,10 +276,13 @@ try_swap_mad_two_srcs(struct ir3_instruction *instr, unsigned new_flags)
if (!is_mad(instr->opc))
return false;
/* NOTE: pre-swap first two src's before valid_flags(),
* which might try to dereference the n'th src:
/* If we've already tried, nothing more to gain.. we will only
* have previously swapped if the original 2nd src was const or
* immed. So swapping back won't improve anything and could
* result in an infinite "progress" loop.
*/
swap(instr->srcs[0], instr->srcs[1]);
if (instr->cat3.swapped)
return false;
/* cat3 doesn't encode immediate, but we can lower immediate
* to const if that helps:
@ -289,6 +292,19 @@ try_swap_mad_two_srcs(struct ir3_instruction *instr, unsigned new_flags)
new_flags |= IR3_REG_CONST;
}
/* If the reason we couldn't fold without swapping is something
* other than const source, then swapping won't help:
*/
if (!(new_flags & IR3_REG_CONST))
return false;
instr->cat3.swapped = true;
/* NOTE: pre-swap first two src's before valid_flags(),
* which might try to dereference the n'th src:
*/
swap(instr->srcs[0], instr->srcs[1]);
bool valid_swap =
/* can we propagate mov if we move 2nd src to first? */
ir3_valid_flags(instr, 0, new_flags) &&