Mesa (main): nir/lower_int64: Fix [iu]mul_high handling

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Module: Mesa
Branch: main
Commit: d0ace287902b1fac4a8ddcb91fac65c99218f01b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d0ace287902b1fac4a8ddcb91fac65c99218f01b

Author: Jason Ekstrand <jason.ekstrand at collabora.com>
Date:   Fri Apr  8 15:06:11 2022 -0500

nir/lower_int64: Fix [iu]mul_high handling

e551040c602d, which added a new mechanism for 64-bit imul which is more
efficient on BDW and later Intel hardware also introduced a bug where we
weren't properly walking both X and Y.  No idea how testing didn't find
this.

Fixes: e551040c602d ("nir/glsl: Add another way of doing lower_imul64 for gen8+"
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6306
Reviewed-by: Matt Turner <mattst88 at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15829>

---

 src/compiler/nir/nir_lower_int64.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/compiler/nir/nir_lower_int64.c b/src/compiler/nir/nir_lower_int64.c
index 7900431ce2d..d5b161206bf 100644
--- a/src/compiler/nir/nir_lower_int64.c
+++ b/src/compiler/nir/nir_lower_int64.c
@@ -455,7 +455,7 @@ lower_mul_high64(nir_builder *b, nir_ssa_def *x, nir_ssa_def *y,
    for (unsigned i = 0; i < 4; i++) {
       nir_ssa_def *carry = NULL;
       for (unsigned j = 0; j < 4; j++) {
-         /* The maximum values of x32[i] and y32[i] are UINT32_MAX so the
+         /* The maximum values of x32[i] and y32[j] are UINT32_MAX so the
           * maximum value of tmp is UINT32_MAX * UINT32_MAX.  The maximum
           * value that will fit in tmp is
           *
@@ -466,7 +466,7 @@ lower_mul_high64(nir_builder *b, nir_ssa_def *x, nir_ssa_def *y,
           * so we're guaranteed that we can add in two more 32-bit values
           * without overflowing tmp.
           */
-         nir_ssa_def *tmp = nir_umul_2x32_64(b, x32[i], y32[i]);
+         nir_ssa_def *tmp = nir_umul_2x32_64(b, x32[i], y32[j]);
 
          if (res[i + j])
             tmp = nir_iadd(b, tmp, nir_u2u64(b, res[i + j]));