pan/bi: Assign registers to ports

Now that we can pack registers given the assigned ports, and we can
assign registers from the indices, the missing link is assigning ports
from the registers, and now finally we get some real data showing up in
a disassembly exercising lots of different code paths.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4242>

diff --git a/src/panfrost/bifrost/bi_pack.c b/src/panfrost/bifrost/bi_pack.c
index 2f463de0bc3ccf69db0a2bf34bf8f4f28ae0771c..3f84c254dc874bf244c99c667c98291c8dc77125 100644 (file)
--- a/src/panfrost/bifrost/bi_pack.c
+++ b/src/panfrost/bifrost/bi_pack.c
@@ -63,6 +63,89 @@ struct bi_registers {
         bool first_instruction;
 };
 
+/* Assigns a port for reading, before anything is written */
+
+static void
+bi_assign_port_read(struct bi_registers *regs, unsigned src)
+{
+        /* We only assign for registers */
+        if (!(src & BIR_INDEX_REGISTER))
+                return;
+
+        unsigned reg = src & ~BIR_INDEX_REGISTER;
+
+        /* Check if we already assigned the port */
+        for (unsigned i = 0; i <= 1; ++i) {
+                if (regs->port[i] == reg && regs->enabled[i])
+                        return;
+        }
+
+        if (regs->port[3] == reg && regs->read_port3)
+                return;
+
+        /* Assign it now */
+
+        for (unsigned i = 0; i <= 1; ++i) {
+                if (!regs->enabled[i]) {
+                        regs->port[i] = reg;
+                        regs->enabled[i] = true;
+                        return;
+                }
+        }
+
+        if (!regs->read_port3) {
+                regs->port[3] = reg;
+                regs->read_port3 = true;
+        }
+}
+
+static struct bi_registers
+bi_assign_ports(bi_bundle now, bi_bundle prev)
+{
+        struct bi_registers regs = { 0 };
+
+        /* First, assign reads */
+
+        if (now.fma)
+                bi_foreach_src(now.fma, src)
+                        bi_assign_port_read(&regs, now.fma->src[src]);
+
+        if (now.add)
+                bi_foreach_src(now.add, src)
+                        bi_assign_port_read(&regs, now.add->src[src]);
+
+        /* Next, assign writes */
+
+        if (prev.fma && prev.fma->dest & BIR_INDEX_REGISTER) {
+                regs.port[2] = prev.fma->dest & ~BIR_INDEX_REGISTER;
+                regs.write_fma = true;
+        }
+
+        if (prev.add && prev.add->dest & BIR_INDEX_REGISTER) {
+                unsigned r = prev.add->dest & ~BIR_INDEX_REGISTER;
+
+                if (regs.write_fma) {
+                        /* Scheduler constraint: cannot read 3 and write 2 */
+                        assert(!regs.read_port3);
+                        regs.port[3] = r;
+                } else {
+                        regs.port[2] = r;
+                }
+
+                regs.write_add = true;
+        }
+
+        /* Finally, ensure port 1 > port 0 for the 63-x trick to function */
+
+        if (regs.enabled[0] && regs.enabled[1] && regs.port[1] < regs.port[0]) {
+                unsigned temp = regs.port[0];
+                regs.port[0] = regs.port[1];
+                regs.port[1] = temp;
+        }
+
+        return regs;
+}
+
 /* Determines the register control field, ignoring the first? flag */
 
 static enum bifrost_reg_control
@@ -174,15 +257,9 @@ struct bi_packed_bundle {
 };
 
 static struct bi_packed_bundle
-bi_pack_bundle(bi_clause *clause, bi_bundle bundle)
+bi_pack_bundle(bi_clause *clause, bi_bundle bundle, bi_bundle prev)
 {
-        struct bi_registers regs = {
-                .enabled = { true, true },
-                .port = { 34, 35, 3, 4 },
-                .write_fma = true,
-                .write_add = true,
-                .first_instruction = true,
-        };
+        struct bi_registers regs = bi_assign_ports(bundle, prev);
 
         uint64_t reg = bi_pack_registers(regs);
         uint64_t fma = bi_pack_fma(clause, bundle);
@@ -200,7 +277,7 @@ static void
 bi_pack_clause(bi_context *ctx, bi_clause *clause, bi_clause *next,
                 struct util_dynarray *emission)
 {
-        struct bi_packed_bundle ins_1 = bi_pack_bundle(clause, clause->bundles[0]);
+        struct bi_packed_bundle ins_1 = bi_pack_bundle(clause, clause->bundles[0], clause->bundles[0]);
         assert(clause->bundle_count == 1);
 
         struct bifrost_fmt1 quad_1 = {