Mesa (staging/21.3): pan/bi: Fix load_const of 1-bit booleans

[GitLab Mirror]

Module: Mesa
Branch: staging/21.3
Commit: 2406855cfb17fbe8b3b51b81cb585fd6174c598e
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=2406855cfb17fbe8b3b51b81cb585fd6174c598e

Author: Alyssa Rosenzweig <alyssa at collabora.com>
Date:   Sat Jan  1 20:38:46 2022 -0500

pan/bi: Fix load_const of 1-bit booleans

For historical reasons, we ingest 1-bit booleans in NIR but expand them
to 16/32-bit booleans in the backend IR. We need to handle this case
when loading boolean constants, extending from 1-bit to 16/32-bit as
required. This issue is masked by effective constant folding for
booleans, but is visible in a shader from Firefox WebRender.

Fixes: 646e03c4519 ("pan/bi: Temporarily switch back to 0/~0 bools")
Signed-off-by: Alyssa Rosenzweig <alyssa at collabora.com>
Reported-by: Icecream95
Closes: #5797
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14371>
(cherry picked from commit 29d319c767394b685e2b421a89a7e8e7103e2688)

---

 .pick_status.json                      |  2 +-
 src/panfrost/bifrost/bifrost_compile.c |  4 +++-
 src/panfrost/bifrost/compiler.h        | 23 +++++++++++++++++++----
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 7ac929737c2..e3cbb0a65eb 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -67,7 +67,7 @@
         "description": "pan/bi: Fix load_const of 1-bit booleans",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "646e03c451980c7082a139ba4a6c7eb370822cc7"
     },
diff --git a/src/panfrost/bifrost/bifrost_compile.c b/src/panfrost/bifrost/bifrost_compile.c
index 44bf2334565..fabdb2bd618 100644
--- a/src/panfrost/bifrost/bifrost_compile.c
+++ b/src/panfrost/bifrost/bifrost_compile.c
@@ -1420,7 +1420,9 @@ bi_emit_load_const(bi_builder *b, nir_load_const_instr *instr)
         uint32_t acc = 0;
 
         for (unsigned i = 0; i < instr->def.num_components; ++i) {
-                unsigned v = nir_const_value_as_uint(instr->value[i], instr->def.bit_size);
+                uint32_t v = nir_const_value_as_uint(instr->value[i], instr->def.bit_size);
+
+                v = bi_extend_constant(v, instr->def.bit_size);
                 acc |= (v << (i * instr->def.bit_size));
         }
 
diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h
index 72a878f13b8..e5dbbe628b3 100644
--- a/src/panfrost/bifrost/compiler.h
+++ b/src/panfrost/bifrost/compiler.h
@@ -701,6 +701,19 @@ bi_temp_reg(bi_context *ctx)
         return bi_get_index(ctx->reg_alloc++, true, 0);
 }
 
+/* NIR booleans are 1-bit (0/1). For now, backend IR booleans are N-bit
+ * (0/~0) where N depends on the context. This requires us to sign-extend
+ * when converting constants from NIR to the backend IR.
+ */
+static inline uint32_t
+bi_extend_constant(uint32_t constant, unsigned bit_size)
+{
+        if (bit_size == 1 && constant != 0)
+                return ~0;
+        else
+                return constant;
+}
+
 /* Inline constants automatically, will be lowered out by bi_lower_fau where a
  * constant is not allowed. load_const_to_scalar gaurantees that this makes
  * sense */
@@ -708,11 +721,13 @@ bi_temp_reg(bi_context *ctx)
 static inline bi_index
 bi_src_index(nir_src *src)
 {
-        if (nir_src_is_const(*src) && nir_src_bit_size(*src) <= 32)
-                return bi_imm_u32(nir_src_as_uint(*src));
-        else if (src->is_ssa)
+        if (nir_src_is_const(*src) && nir_src_bit_size(*src) <= 32) {
+                uint32_t v = nir_src_as_uint(*src);
+
+                return bi_imm_u32(bi_extend_constant(v, nir_src_bit_size(*src)));
+        } else if (src->is_ssa) {
                 return bi_get_index(src->ssa->index, false, 0);
-        else {
+        } else {
                 assert(!src->reg.indirect);
                 return bi_get_index(src->reg.reg->index, true, 0);
         }