Mesa (master): vc4: Restructure VPM write optimization into two passes.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: f4baf809937c98dabee90ea57b9d7e6135bdb0df
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f4baf809937c98dabee90ea57b9d7e6135bdb0df

Author: Eric Anholt <eric at anholt.net>
Date:   Tue Nov 15 14:35:12 2016 -0800

vc4: Restructure VPM write optimization into two passes.

For texturing, there won't be a fixed limit on how many writes there are,
so we need to compute uses up front.

---

 .../drivers/vc4/vc4_opt_coalesce_ff_writes.c       | 28 ++++++++--------------
 1 file changed, 10 insertions(+), 18 deletions(-)

diff --git a/src/gallium/drivers/vc4/vc4_opt_coalesce_ff_writes.c b/src/gallium/drivers/vc4/vc4_opt_coalesce_ff_writes.c
index 4e5b119..c08c026 100644
--- a/src/gallium/drivers/vc4/vc4_opt_coalesce_ff_writes.c
+++ b/src/gallium/drivers/vc4/vc4_opt_coalesce_ff_writes.c
@@ -42,20 +42,10 @@ qir_opt_coalesce_ff_writes(struct vc4_compile *c)
                 return false;
 
         bool progress = false;
-        struct qinst *vpm_writes[64] = { 0 };
         uint32_t use_count[c->num_temps];
-        uint32_t vpm_write_count = 0;
         memset(&use_count, 0, sizeof(use_count));
 
         qir_for_each_inst_inorder(inst, c) {
-                switch (inst->dst.file) {
-                case QFILE_VPM:
-                        vpm_writes[vpm_write_count++] = inst;
-                        break;
-                default:
-                        break;
-                }
-
                 for (int i = 0; i < qir_get_nsrc(inst); i++) {
                         if (inst->src[i].file == QFILE_TEMP) {
                                 uint32_t temp = inst->src[i].index;
@@ -64,13 +54,16 @@ qir_opt_coalesce_ff_writes(struct vc4_compile *c)
                 }
         }
 
-        for (int i = 0; i < vpm_write_count; i++) {
-                if (!qir_is_raw_mov(vpm_writes[i]) ||
-                    vpm_writes[i]->src[0].file != QFILE_TEMP) {
+        qir_for_each_inst_inorder(mov_inst, c) {
+                if (!qir_is_raw_mov(mov_inst) || mov_inst->sf)
+                        continue;
+                if (mov_inst->src[0].file != QFILE_TEMP)
+                        continue;
+
+                if (mov_inst->dst.file != QFILE_VPM)
                         continue;
-                }
 
-                uint32_t temp = vpm_writes[i]->src[0].index;
+                uint32_t temp = mov_inst->src[0].index;
                 if (use_count[temp] != 1)
                         continue;
 
@@ -89,10 +82,9 @@ qir_opt_coalesce_ff_writes(struct vc4_compile *c)
                 /* Move the generating instruction to the end of the program
                  * to maintain the order of the VPM writes.
                  */
-                assert(!vpm_writes[i]->sf);
                 list_del(&inst->link);
-                list_addtail(&inst->link, &vpm_writes[i]->link);
-                qir_remove_instruction(c, vpm_writes[i]);
+                list_addtail(&inst->link, &mov_inst->link);
+                qir_remove_instruction(c, mov_inst);
 
                 c->defs[inst->dst.index] = NULL;
                 inst->dst.file = QFILE_VPM;