From 8a450fb0ffb230c6ee3ef96faa8ce629085a3204 Mon Sep 17 00:00:00 2001
From: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
Date: Thu, 19 Feb 2026 21:57:38 -0500
Subject: [PATCH] nir/lower_subgroups: generalize vote lowering

We currently have code to lower quad votes to a ballot. The same idea works for
subgroup votes. Generalize the quad vote code and use it to lower
vote_all/vote_eq for backends setting a new lower_vote option.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40074>
---
 src/compiler/nir/nir.h                 |  1 +
 src/compiler/nir/nir_lower_subgroups.c | 28 +++++++++++++++-----------
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 3b64f419990..ff6a139227e 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -5787,6 +5787,7 @@ typedef struct nir_lower_subgroups_options {
    uint8_t ballot_bit_size;
    uint8_t ballot_components;
    bool lower_to_scalar : 1;
+   bool lower_vote : 1;
    bool lower_vote_trivial : 1;
    bool lower_vote_feq : 1;
    bool lower_vote_ieq : 1;
diff --git a/src/compiler/nir/nir_lower_subgroups.c b/src/compiler/nir/nir_lower_subgroups.c
index bede202b9e6..1e1c52b704d 100644
--- a/src/compiler/nir/nir_lower_subgroups.c
+++ b/src/compiler/nir/nir_lower_subgroups.c
@@ -980,15 +980,19 @@ build_subgroup_gt_mask(nir_builder *b,
 }
 
 static nir_def *
-build_quad_vote_any(nir_builder *b, nir_def *src,
-                    const nir_lower_subgroups_options *options)
+build_vote(nir_builder *b, nir_def *src,
+           const nir_lower_subgroups_options *options,
+           unsigned cluster_size, bool all)
 {
    nir_def *ballot = nir_ballot(b, options->ballot_components,
                                 options->ballot_bit_size,
-                                src);
-   nir_def *mask = build_cluster_mask(b, 4, options);
+                                all ? nir_inot(b, src) : src);
+   if (cluster_size) {
+      nir_def *mask = build_cluster_mask(b, cluster_size, options);
+      ballot = nir_iand(b, ballot, mask);
+   }
 
-   return nir_ine_imm(b, nir_iand(b, ballot, mask), 0);
+   return all ? nir_ieq_imm(b, ballot, 0) : nir_ine_imm(b, ballot, 0);
 }
 
 static nir_def *
@@ -1088,8 +1092,12 @@ lower_subgroups_instr(nir_builder *b, nir_instr *instr, void *_options)
    switch (intrin->intrinsic) {
    case nir_intrinsic_vote_any:
    case nir_intrinsic_vote_all:
-      if (options->lower_vote_trivial)
+      if (options->lower_vote_trivial) {
          return intrin->src[0].ssa;
+      } else if (options->lower_vote) {
+         return build_vote(b, intrin->src[0].ssa, options, 0,
+                           intrin->intrinsic == nir_intrinsic_vote_all);
+      }
       break;
 
    case nir_intrinsic_vote_feq:
@@ -1337,14 +1345,10 @@ lower_subgroups_instr(nir_builder *b, nir_instr *instr, void *_options)
       break;
 
    case nir_intrinsic_quad_vote_any:
-      if (options->lower_quad_vote)
-         return build_quad_vote_any(b, intrin->src[0].ssa, options);
-      break;
    case nir_intrinsic_quad_vote_all:
       if (options->lower_quad_vote) {
-         nir_def *not_src = nir_inot(b, intrin->src[0].ssa);
-         nir_def *any_not = build_quad_vote_any(b, not_src, options);
-         return nir_inot(b, any_not);
+         return build_vote(b, intrin->src[0].ssa, options, 4,
+                           intrin->intrinsic == nir_intrinsic_quad_vote_all);
       }
       break;