panfrost/blend: Fix invalid const values leading to NIR validation errors

Using a designated initializer like this leaves padding bits, which form
part of the aliasing u64/f64 member of the union, uninitialised, but a
nir_const_value must always have the unused bits zeroed out. Thus, use
the nir_const_value_for_float helper instead like everywhere else which
will do a memset 0 for us first.

Without this, using the pan_blend shader in a build with validation
enabled fails with:

  NIR validation failed after nir_lower_vars_to_ssa
  ...
            vec4 32 ssa_58 = load_const (0x3f7cfcfd /* 0.988235 */, 0x3f7cfcfd /* 0.988235 */, 0x3f7cfcfd /* 0.988235 */, 0x3f800000 /* 1.000000 */)
  error: memcmp(val, &cmp_val, sizeof(cmp_val)) == 0 (../src/compiler/nir/nir_validate.c:976)

Fixes: 1378c67bcf9e ("panfrost/blend: Inline blend constants")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20071>
(cherry picked from commit 750325730bb84981f68d78b205fb0cec1e165100)

diff --git a/.pick_status.json b/.pick_status.json
index 2821ca0..81b1409 100644 (file)
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -202,7 +202,7 @@
         "description": "panfrost/blend: Fix invalid const values leading to NIR validation errors",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "1378c67bcf9e16aea98ddb8cb6bd37b9ed4e3a81"
     },

diff --git a/src/panfrost/lib/pan_blend.c b/src/panfrost/lib/pan_blend.c
index 811b22e..f6e6bf6 100644 (file)
--- a/src/panfrost/lib/pan_blend.c
+++ b/src/panfrost/lib/pan_blend.c
@@ -587,10 +587,10 @@ pan_inline_blend_constants(nir_builder *b, nir_instr *instr, void *data)
 
         float *floats = data;
         const nir_const_value constants[4] = {
-                { .f32 = floats[0] },
-                { .f32 = floats[1] },
-                { .f32 = floats[2] },
-                { .f32 = floats[3] }
+                nir_const_value_for_float(floats[0], 32),
+                nir_const_value_for_float(floats[1], 32),
+                nir_const_value_for_float(floats[2], 32),
+                nir_const_value_for_float(floats[3], 32)
         };
 
         b->cursor = nir_after_instr(instr);