vc4: Split optimizing VPM writes from VPM reads.

The VPM write logic will be basically the same as the texture coordinate
write logic we need, and it's not really related to the VPM read logic
other than the reuse of the use_count array.

5 files changed, 110 insertions, 51 deletions

diff --git a/src/gallium/drivers/vc4/Makefile.sources b/src/gallium/drivers/vc4/Makefile.sources
index e1496d1012a..f09dac24848 100644
--- a/src/gallium/drivers/vc4/Makefile.sources
+++ b/src/gallium/drivers/vc4/Makefile.sources
@@ -28,6 +28,7 @@ C_SOURCES := \
 	vc4_opt_peephole_sf.c \
 	vc4_opt_small_immediates.c \
 	vc4_opt_vpm.c \
+	vc4_opt_coalesce_ff_writes.c \
 	vc4_program.c \
 	vc4_qir.c \
 	vc4_qir_emit_uniform_stream_resets.c \
diff --git a/src/gallium/drivers/vc4/vc4_opt_coalesce_ff_writes.c b/src/gallium/drivers/vc4/vc4_opt_coalesce_ff_writes.c
new file mode 100644
index 00000000000..4e5b1193d3a
--- /dev/null
+++ b/src/gallium/drivers/vc4/vc4_opt_coalesce_ff_writes.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright © 2014 Broadcom
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/**
+ * @file vc4_opt_coalesce_ff_writes.c
+ *
+ * This modifies instructions that generate the value consumed by a VPM write
+ * to write directly into the VPM.
+ */
+
+#include "vc4_qir.h"
+
+bool
+qir_opt_coalesce_ff_writes(struct vc4_compile *c)
+{
+        if (c->stage == QSTAGE_FRAG)
+                return false;
+
+        /* For now, only do this pass when we don't have control flow. */
+        struct qblock *block = qir_entry_block(c);
+        if (block != qir_exit_block(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;
+                                use_count[temp]++;
+                        }
+                }
+        }
+
+        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) {
+                        continue;
+                }
+
+                uint32_t temp = vpm_writes[i]->src[0].index;
+                if (use_count[temp] != 1)
+                        continue;
+
+                struct qinst *inst = c->defs[temp];
+                if (!inst)
+                        continue;
+
+                if (qir_depends_on_flags(inst) || inst->sf)
+                        continue;
+
+                if (qir_has_side_effects(c, inst) ||
+                    qir_has_side_effect_reads(c, inst)) {
+                        continue;
+                }
+
+                /* 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]);
+
+                c->defs[inst->dst.index] = NULL;
+                inst->dst.file = QFILE_VPM;
+                inst->dst.index = 0;
+
+                progress = true;
+        }
+
+        return progress;
+}
diff --git a/src/gallium/drivers/vc4/vc4_opt_vpm.c b/src/gallium/drivers/vc4/vc4_opt_vpm.c
index b3bef272254..6f196e7d1b9 100644
--- a/src/gallium/drivers/vc4/vc4_opt_vpm.c
+++ b/src/gallium/drivers/vc4/vc4_opt_vpm.c
@@ -24,10 +24,8 @@
 /**
  * @file vc4_opt_vpm.c
  *
- * This modifies instructions that:
- * 1. exclusively consume a value read from the VPM to directly read the VPM if
- *    other operands allow it.
- * 2. generate the value consumed by a VPM write to write directly into the VPM.
+ * This modifies instructions that exclusively consume a value read from the
+ * VPM to directly read the VPM if other operands allow it.
  */
 
 #include "vc4_qir.h"
@@ -44,20 +42,10 @@ qir_opt_vpm(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;
@@ -127,42 +115,5 @@ qir_opt_vpm(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) {
-                        continue;
-                }
-
-                uint32_t temp = vpm_writes[i]->src[0].index;
-                if (use_count[temp] != 1)
-                        continue;
-
-                struct qinst *inst = c->defs[temp];
-                if (!inst)
-                        continue;
-
-                if (qir_depends_on_flags(inst) || inst->sf)
-                        continue;
-
-                if (qir_has_side_effects(c, inst) ||
-                    qir_has_side_effect_reads(c, inst)) {
-                        continue;
-                }
-
-                /* 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]);
-
-                c->defs[inst->dst.index] = NULL;
-                inst->dst.file = QFILE_VPM;
-                inst->dst.index = 0;
-
-                progress = true;
-        }
-
         return progress;
 }
diff --git a/src/gallium/drivers/vc4/vc4_qir.c b/src/gallium/drivers/vc4/vc4_qir.c
index 7c556a98ea2..a082c41dfe0 100644
--- a/src/gallium/drivers/vc4/vc4_qir.c
+++ b/src/gallium/drivers/vc4/vc4_qir.c
@@ -784,6 +784,7 @@ qir_optimize(struct vc4_compile *c)
                 OPTPASS(qir_opt_dead_code);
                 OPTPASS(qir_opt_small_immediates);
                 OPTPASS(qir_opt_vpm);
+                OPTPASS(qir_opt_coalesce_ff_writes);
 
                 if (!progress)
                         break;
diff --git a/src/gallium/drivers/vc4/vc4_qir.h b/src/gallium/drivers/vc4/vc4_qir.h
index 99cc957853a..a8f90cfe7af 100644
--- a/src/gallium/drivers/vc4/vc4_qir.h
+++ b/src/gallium/drivers/vc4/vc4_qir.h
@@ -595,6 +595,7 @@ void qir_validate(struct vc4_compile *c);
 
 void qir_optimize(struct vc4_compile *c);
 bool qir_opt_algebraic(struct vc4_compile *c);
+bool qir_opt_coalesce_ff_writes(struct vc4_compile *c);
 bool qir_opt_constant_folding(struct vc4_compile *c);
 bool qir_opt_copy_propagation(struct vc4_compile *c);
 bool qir_opt_dead_code(struct vc4_compile *c);