[Mesa-dev] [PATCH 12/30] pan/midgard: Add constant intersection filters

[Alyssa Rosenzweig]

In the future, we will want to keep track of which components of
constants of various sizes correspond to which parts of the bundle
constants, like in the old scheduler. For now, let's just stub it out
for a simple rule of one instruction with embedded constants per bundle.
We can eventually do better, of course.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
---
 src/panfrost/midgard/midgard_schedule.c | 55 +++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/src/panfrost/midgard/midgard_schedule.c b/src/panfrost/midgard/midgard_schedule.c
index 72c6ec42980..86a77149c78 100644
--- a/src/panfrost/midgard/midgard_schedule.c
+++ b/src/panfrost/midgard/midgard_schedule.c
@@ -817,8 +817,63 @@ struct midgard_predicate {
 
         /* True if we want to pop off the chosen instruction */
         bool destructive;
+
+        /* State for bundle constants. constants is the actual constants
+         * for the bundle. constant_count is the number of bytes (up to
+         * 16) currently in use for constants. When picking in destructive
+         * mode, the constants array will be updated, and the instruction
+         * will be adjusted to index into the constants array */
+
+        uint8_t *constants;
+        unsigned constant_count;
+        bool blend_constant;
 };
 
+/* For an instruction that can fit, adjust it to fit and update the constants
+ * array, in destructive mode. Returns whether the fitting was successful. */
+
+static bool
+mir_adjust_constants(midgard_instruction *ins,
+                struct midgard_predicate *pred,
+                bool destructive)
+{
+        /* Blend constants dominate */
+        if (ins->has_blend_constant) {
+                if (pred->constant_count)
+                        return false;
+                else if (destructive) {
+                        pred->blend_constant = true;
+                        pred->constant_count = 16;
+                        return true;
+                }
+        }
+
+        /* No constant, nothing to adjust */
+        if (!ins->has_constants)
+                return true;
+
+        /* TODO: Deduplicate; permit multiple constants within a bundle */
+
+        if (destructive && !pred->constant_count) {
+                if (ins->alu.reg_mode == midgard_reg_mode_16) {
+                      /* TODO: Fix packing XXX */
+                        uint16_t *bundles = (uint16_t *) pred->constants;
+                        uint32_t *constants = (uint32_t *) ins->constants;
+
+                        /* Copy them wholesale */
+                        for (unsigned i = 0; i < 4; ++i)
+                                bundles[i] = constants[i];
+                } else {
+                        memcpy(pred->constants, ins->constants, 16);
+                }
+
+                pred->constant_count = 16;
+                return true;
+        }
+
+        return !pred->constant_count;
+}
+
 static midgard_instruction *
 mir_choose_instruction(
                 midgard_instruction **instructions,
-- 
2.23.0