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nir/lower_int64: replace uadd_sat with ior for find_lsb64 and ufind_msb64

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Using ior here is equivalent to using uadd_sat, but works for every driver
and shouldn't hurt anywhere.

I forgot to fix this up when fixing up some vvl errors with zink.

Fixes crashes with the integer_ctz CL CTS tests in zink.

Fixes: 39ec184db6 ("zink: lower 64 bit find_lsb, ufind_msb and bit_count")
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30535>
(cherry picked from commit 48acf9d358)
This commit is contained in:
Georg Lehmann 2024-08-06 14:09:08 +02:00 • committed by Eric Engestrom
parent f3f0b87bf8
commit ff7759cdfe
2 changed files with 10 additions and 23 deletions
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2
.pick_status.json
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@ -2204,7 +2204,7 @@
"description": "nir/lower_int64: replace uadd_sat with ior for find_lsb64 and ufind_msb64",
"nominated": true,
"nomination_type": 1,
"resolution": 0,
"resolution": 1,
"main_sha": null,
"because_sha": "39ec184db6e9d614fd540b89e9cba4e6cb77de50",
"notes": null

31
src/compiler/nir/nir_lower_int64.c
View file

@ -683,24 +683,13 @@ lower_ufind_msb64(nir_builder *b, nir_def *x)
nir_def *lo_count = nir_ufind_msb(b, x_lo);
nir_def *hi_count = nir_ufind_msb(b, x_hi);
if (b->shader->options->lower_uadd_sat) {
nir_def *valid_hi_bits = nir_ine_imm(b, x_hi, 0);
nir_def *hi_res = nir_iadd_imm(b, hi_count, 32);
return nir_bcsel(b, valid_hi_bits, hi_res, lo_count);
} else {
/* If hi_count was -1, it will still be -1 after this uadd_sat. As a
* result, hi_count is either -1 or the correct return value for 64-bit
* ufind_msb.
*/
nir_def *hi_res = nir_uadd_sat(b, nir_imm_intN_t(b, 32, 32), hi_count);
/* hi_res is either -1 or a value in the range [63, 32]. lo_count is
* either -1 or a value in the range [31, 0]. The imax will pick
* lo_count only when hi_res is -1. In those cases, lo_count is
* guaranteed to be the correct answer.
*/
return nir_imax(b, hi_res, lo_count);
}
/* hi_count is either -1 or a value in the range [31, 0]. lo_count is
* the same. The imax will pick lo_count only when hi_count is -1. In those
* cases, lo_count is guaranteed to be the correct answer.
* The ior 32 is always safe here as with -1 the value won't change,
* otherwise it adds 32, which is what we want anyway.
*/
return nir_imax(b, lo_count, nir_ior_imm(b, hi_count, 32));
}
static nir_def *
@ -713,11 +702,9 @@ lower_find_lsb64(nir_builder *b, nir_def *x)
/* Use umin so that -1 (no bits found) becomes larger (0xFFFFFFFF)
* than any actual bit position, so we return a found bit instead.
* This is similar to the ufind_msb lowering. If you need this lowering
* without uadd_sat, add code like in lower_ufind_msb64.
* This is similar to the ufind_msb lowering.
*/
assert(!b->shader->options->lower_uadd_sat);
return nir_umin(b, lo_lsb, nir_uadd_sat(b, hi_lsb, nir_imm_int(b, 32)));
return nir_umin(b, lo_lsb, nir_ior_imm(b, hi_lsb, 32));
}
static nir_def *