panfrost: Fix blend constant fetch prototype

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Fixes: 93824b6451 ("panfrost: Move the blend logic out of the gallium driver")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10869>

src/gallium/drivers/panfrost/pan_blend_cso.c

@@ -145,9 +145,12 @@ panfrost_get_blend_for_context(struct panfrost_context *ctx, unsigned rti, struc
 
         /* First, we'll try fixed function, matching equation and constant */
         if (pan_blend_can_fixed_function(dev, &pan_blend, rti)) {
+                const struct pan_blend_equation eq = pan_blend.rts[rti].equation;
+                unsigned constant_mask = pan_blend_constant_mask(eq);
+
                 struct panfrost_blend_final final = {
                         .load_dest = pan_blend_reads_dest(pan_blend.rts[rti].equation),
-                        .equation.constant = pan_blend_get_constant(dev, &pan_blend, rti),
+                        .equation.constant = pan_blend_get_constant(constant_mask, ctx->blend_color.color),
                         .opaque = pan_blend_is_opaque(pan_blend.rts[rti].equation),
                         .no_colour = pan_blend.rts[rti].equation.color_mask == 0,
                 };

src/panfrost/lib/pan_blend.c

@@ -78,15 +78,12 @@ blend_factor_constant_mask(enum blend_factor factor)
 }
 
 unsigned
-pan_blend_constant_mask(const struct pan_blend_state *state,
-                        unsigned rt)
+pan_blend_constant_mask(const struct pan_blend_equation eq)
 {
-        const struct pan_blend_equation *e = &state->rts[rt].equation;
-
-        return blend_factor_constant_mask(e->rgb_src_factor) |
-               blend_factor_constant_mask(e->rgb_dst_factor) |
-               blend_factor_constant_mask(e->alpha_src_factor) |
-               blend_factor_constant_mask(e->alpha_dst_factor);
+        return blend_factor_constant_mask(eq.rgb_src_factor) |
+               blend_factor_constant_mask(eq.rgb_dst_factor) |
+               blend_factor_constant_mask(eq.alpha_src_factor) |
+               blend_factor_constant_mask(eq.alpha_dst_factor);
 }
 
 static bool
@@ -94,7 +91,7 @@ can_blend_constant(const struct panfrost_device *dev,
                    const struct pan_blend_state *state,
                    unsigned rt)
 {
-        unsigned constant_mask = pan_blend_constant_mask(state, rt);
+        unsigned constant_mask = pan_blend_constant_mask(state->rts[rt].equation);
         if (!constant_mask)
                 return true;
 
@@ -107,33 +104,16 @@ can_blend_constant(const struct panfrost_device *dev,
         if (dev->arch == 7 && rt > 0)
                 return false;
 
-        unsigned first_constant = ffs(constant_mask) - 1;
-        float constant = state->constants[first_constant];
+        float constant = pan_blend_get_constant(constant_mask, state->constants);
 
-        for (unsigned i = first_constant + 1; i < ARRAY_SIZE(state->constants); i++) {
-                if (((1 << i) & constant_mask) &&
-                    state->constants[i] != constant)
+        u_foreach_bit(i, constant_mask) {
+                if (state->constants[i] != constant)
                         return false;
         }
 
         return true;
 }
 
-float
-pan_blend_get_constant(ASSERTED const struct panfrost_device *dev,
-                       const struct pan_blend_state *state,
-                       unsigned rt)
-{
-        assert(can_blend_constant(dev, state, rt));
-
-        unsigned constant_mask = pan_blend_constant_mask(state, rt);
-
-        if (!constant_mask)
-                return 0.0f;
-
-        return state->constants[ffs(constant_mask) - 1];
-}
-
 bool
 pan_blend_can_fixed_function(const struct panfrost_device *dev,
                              const struct pan_blend_state *state,
@@ -642,7 +622,7 @@ pan_blend_get_shader_locked(const struct panfrost_device *dev,
                 .src0_type = src0_type,
                 .src1_type = src1_type,
                 .rt = rt,
-                .has_constants = pan_blend_constant_mask(state, rt) != 0,
+                .has_constants = pan_blend_constant_mask(state->rts[rt].equation) != 0,
                 .logicop_enable = state->logicop_enable,
                 .logicop_func = state->logicop_func,
                 .nr_samples = state->rts[rt].nr_samples,

src/panfrost/lib/pan_blend.h

@@ -108,13 +108,17 @@ bool
 pan_blend_is_opaque(const struct pan_blend_equation eq);
 
 unsigned
-pan_blend_constant_mask(const struct pan_blend_state *state,
-                        unsigned rt);
+pan_blend_constant_mask(const struct pan_blend_equation eq);
 
-float
-pan_blend_get_constant(const struct panfrost_device *dev,
-                       const struct pan_blend_state *state,
-                       unsigned rt);
+/* Fixed-function blending only supports a single constant, so if multiple bits
+ * are set in constant_mask, the constants must match. Therefore we may pick
+ * just the first constant. */
+
+static inline float
+pan_blend_get_constant(unsigned mask, float *constants)
+{
+        return mask ? constants[ffs(mask) - 1] : 0.0;
+}
 
 void
 pan_blend_to_fixed_function_equation(const struct panfrost_device *dev,