vc4: Interleave register allocation from regfile A and B.

The register allocator prefers low-index registers from vc4_regs[] in the
configuration we're using, which is good because it means we prioritize
allocating the accumulators (which are faster).  On the other hand, it was
causing raddr conflicts because everything beyond r0-r2 ended up in
regfile A until you got massive register pressure.  By interleaving, we
end up getting more instruction pairing from getting non-conflicting
raddrs and QPU_WSes.

total instructions in shared programs: 55957 -> 52719 (-5.79%)
instructions in affected programs:     46855 -> 43617 (-6.91%)

diff --git a/src/gallium/drivers/vc4/vc4_register_allocate.c b/src/gallium/drivers/vc4/vc4_register_allocate.c
index 72f5271d653b09e94fb3146e56bdc136f5d755e6..b62669feb30807babf4472477e211d50dcefbb08 100644 (file)
--- a/src/gallium/drivers/vc4/vc4_register_allocate.c
+++ b/src/gallium/drivers/vc4/vc4_register_allocate.c
@@ -36,80 +36,79 @@ static const struct qpu_reg vc4_regs[] = {
         { QPU_MUX_R3, 0},
         { QPU_MUX_R4, 0},
         QPU_R(A, 0),
-        QPU_R(A, 1),
-        QPU_R(A, 2),
-        QPU_R(A, 3),
-        QPU_R(A, 4),
-        QPU_R(A, 5),
-        QPU_R(A, 6),
-        QPU_R(A, 7),
-        QPU_R(A, 8),
-        QPU_R(A, 9),
-        QPU_R(A, 10),
-        QPU_R(A, 11),
-        QPU_R(A, 12),
-        QPU_R(A, 13),
-        QPU_R(A, 14),
-        QPU_R(A, 15),
-        QPU_R(A, 16),
-        QPU_R(A, 17),
-        QPU_R(A, 18),
-        QPU_R(A, 19),
-        QPU_R(A, 20),
-        QPU_R(A, 21),
-        QPU_R(A, 22),
-        QPU_R(A, 23),
-        QPU_R(A, 24),
-        QPU_R(A, 25),
-        QPU_R(A, 26),
-        QPU_R(A, 27),
-        QPU_R(A, 28),
-        QPU_R(A, 29),
-        QPU_R(A, 30),
-        QPU_R(A, 31),
         QPU_R(B, 0),
+        QPU_R(A, 1),
         QPU_R(B, 1),
+        QPU_R(A, 2),
         QPU_R(B, 2),
+        QPU_R(A, 3),
         QPU_R(B, 3),
+        QPU_R(A, 4),
         QPU_R(B, 4),
+        QPU_R(A, 5),
         QPU_R(B, 5),
+        QPU_R(A, 6),
         QPU_R(B, 6),
+        QPU_R(A, 7),
         QPU_R(B, 7),
+        QPU_R(A, 8),
         QPU_R(B, 8),
+        QPU_R(A, 9),
         QPU_R(B, 9),
+        QPU_R(A, 10),
         QPU_R(B, 10),
+        QPU_R(A, 11),
         QPU_R(B, 11),
+        QPU_R(A, 12),
         QPU_R(B, 12),
+        QPU_R(A, 13),
         QPU_R(B, 13),
+        QPU_R(A, 14),
         QPU_R(B, 14),
+        QPU_R(A, 15),
         QPU_R(B, 15),
+        QPU_R(A, 16),
         QPU_R(B, 16),
+        QPU_R(A, 17),
         QPU_R(B, 17),
+        QPU_R(A, 18),
         QPU_R(B, 18),
+        QPU_R(A, 19),
         QPU_R(B, 19),
+        QPU_R(A, 20),
         QPU_R(B, 20),
+        QPU_R(A, 21),
         QPU_R(B, 21),
+        QPU_R(A, 22),
         QPU_R(B, 22),
+        QPU_R(A, 23),
         QPU_R(B, 23),
+        QPU_R(A, 24),
         QPU_R(B, 24),
+        QPU_R(A, 25),
         QPU_R(B, 25),
+        QPU_R(A, 26),
         QPU_R(B, 26),
+        QPU_R(A, 27),
         QPU_R(B, 27),
+        QPU_R(A, 28),
         QPU_R(B, 28),
+        QPU_R(A, 29),
         QPU_R(B, 29),
+        QPU_R(A, 30),
         QPU_R(B, 30),
+        QPU_R(A, 31),
         QPU_R(B, 31),
 };
 #define ACC_INDEX     0
-#define A_INDEX       (ACC_INDEX + 5)
-#define B_INDEX       (A_INDEX + 32)
+#define AB_INDEX      (ACC_INDEX + 5)
 
 static void
 vc4_alloc_reg_set(struct vc4_context *vc4)
 {
-        assert(vc4_regs[A_INDEX].addr == 0);
-        assert(vc4_regs[B_INDEX].addr == 0);
-        STATIC_ASSERT(ARRAY_SIZE(vc4_regs) == B_INDEX + 32);
+        assert(vc4_regs[AB_INDEX].addr == 0);
+        assert(vc4_regs[AB_INDEX + 1].addr == 0);
+        STATIC_ASSERT(ARRAY_SIZE(vc4_regs) == AB_INDEX + 64);
 
         if (vc4->regs)
                 return;
@@ -134,7 +133,7 @@ vc4_alloc_reg_set(struct vc4_context *vc4)
         }
 
         vc4->reg_class_a = ra_alloc_reg_class(vc4->regs);
-        for (uint32_t i = A_INDEX; i < A_INDEX + 32; i++)
+        for (uint32_t i = AB_INDEX; i < AB_INDEX + 64; i += 2)
                 ra_class_add_reg(vc4->regs, vc4->reg_class_a, i);
 
         ra_set_finalize(vc4->regs, NULL);
@@ -191,13 +190,13 @@ vc4_register_allocate(struct vc4_context *vc4, struct vc4_compile *c)
                 case QOP_FRAG_Z:
                         def[inst->dst.index] = 0;
                         ra_set_node_reg(g, inst->dst.index,
-                                        B_INDEX + QPU_R_FRAG_PAYLOAD_ZW);
+                                        AB_INDEX + QPU_R_FRAG_PAYLOAD_ZW * 2 + 1);
                         break;
 
                 case QOP_FRAG_W:
                         def[inst->dst.index] = 0;
                         ra_set_node_reg(g, inst->dst.index,
-                                        A_INDEX + QPU_R_FRAG_PAYLOAD_ZW);
+                                        AB_INDEX + QPU_R_FRAG_PAYLOAD_ZW * 2);
                         break;
 
                 case QOP_TEX_RESULT: