vc4: Allow QIR registers to be non-SSA.

Now that we have NIR, most of the optimization we still need to do is
peepholes on instruction selection rather than general dataflow
operations.  This means we want to be able to have QIR be a lot closer to
the actual QPU instructions, just with virtual registers.  Allowing
multiple instructions writing the same register opens up a lot of
possibilities.

diff --git a/src/gallium/drivers/vc4/vc4_opt_algebraic.c b/src/gallium/drivers/vc4/vc4_opt_algebraic.c
index 7978ea1829fc43ae48be2e1c9aa3763f2c365725..22304e119303d30a29d6240cffb553953ad33773 100644 (file)
--- a/src/gallium/drivers/vc4/vc4_opt_algebraic.c
+++ b/src/gallium/drivers/vc4/vc4_opt_algebraic.c
@@ -207,6 +207,7 @@ qir_opt_algebraic(struct vc4_compile *c)
 
                         /* FADD(a, FSUB(0, b)) -> FSUB(a, b) */
                         if (inst->src[1].file == QFILE_TEMP &&
+                            c->defs[inst->src[1].index] &&
                             c->defs[inst->src[1].index]->op == QOP_FSUB) {
                                 struct qinst *fsub = c->defs[inst->src[1].index];
                                 if (is_zero(c, fsub->src[0])) {
@@ -221,6 +222,7 @@ qir_opt_algebraic(struct vc4_compile *c)
 
                         /* FADD(FSUB(0, b), a) -> FSUB(a, b) */
                         if (inst->src[0].file == QFILE_TEMP &&
+                            c->defs[inst->src[0].index] &&
                             c->defs[inst->src[0].index]->op == QOP_FSUB) {
                                 struct qinst *fsub = c->defs[inst->src[0].index];
                                 if (is_zero(c, fsub->src[0])) {

diff --git a/src/gallium/drivers/vc4/vc4_opt_vpm_writes.c b/src/gallium/drivers/vc4/vc4_opt_vpm_writes.c
index fc7d4aa025aa28f2dff7cb753d94bc90a21fc022..f2cdf8f694fd9cc2bc6dbb7c51786162987664b1 100644 (file)
--- a/src/gallium/drivers/vc4/vc4_opt_vpm_writes.c
+++ b/src/gallium/drivers/vc4/vc4_opt_vpm_writes.c
@@ -68,7 +68,7 @@ qir_opt_vpm_writes(struct vc4_compile *c)
                         continue;
 
                 struct qinst *inst = c->defs[temp];
-                if (qir_is_multi_instruction(inst))
+                if (!inst || qir_is_multi_instruction(inst))
                         continue;
 
                 if (qir_depends_on_flags(inst) || inst->sf)

diff --git a/src/gallium/drivers/vc4/vc4_qir.c b/src/gallium/drivers/vc4/vc4_qir.c
index 254140a72f563621b028dd700c3e65538ba97dbf..90d1c1ff69b4d6ab216fd039e22c3ed99117a24c 100644 (file)
--- a/src/gallium/drivers/vc4/vc4_qir.c
+++ b/src/gallium/drivers/vc4/vc4_qir.c
@@ -389,8 +389,11 @@ qir_remove_instruction(struct vc4_compile *c, struct qinst *qinst)
 struct qreg
 qir_follow_movs(struct vc4_compile *c, struct qreg reg)
 {
-        while (reg.file == QFILE_TEMP && c->defs[reg.index]->op == QOP_MOV)
+        while (reg.file == QFILE_TEMP &&
+               c->defs[reg.index] &&
+               c->defs[reg.index]->op == QOP_MOV) {
                 reg = c->defs[reg.index]->src[0];
+        }
 
         return reg;
 }

diff --git a/src/gallium/drivers/vc4/vc4_register_allocate.c b/src/gallium/drivers/vc4/vc4_register_allocate.c
index b83500ceac139871c63bf0c108f6edf7c0e9b6ed..fa67a3a5911e1e82daeaaf6cbcaf80f5e157fc27 100644 (file)
--- a/src/gallium/drivers/vc4/vc4_register_allocate.c
+++ b/src/gallium/drivers/vc4/vc4_register_allocate.c
@@ -177,7 +177,8 @@ vc4_register_allocate(struct vc4_context *vc4, struct vc4_compile *c)
         uint8_t class_bits[c->num_temps];
         struct qpu_reg *temp_registers = calloc(c->num_temps,
                                                 sizeof(*temp_registers));
-        memset(def, 0, sizeof(def));
+        for (int i = 0; i < ARRAY_SIZE(def); i++)
+                def[i] = ~0;
         memset(use, 0, sizeof(use));
 
         /* If things aren't ever written (undefined values), just read from
@@ -196,7 +197,7 @@ vc4_register_allocate(struct vc4_context *vc4, struct vc4_compile *c)
         uint32_t ip = 0;
         list_for_each_entry(struct qinst, inst, &c->instructions, link) {
                 if (inst->dst.file == QFILE_TEMP) {
-                        def[inst->dst.index] = ip;
+                        def[inst->dst.index] = MIN2(ip, def[inst->dst.index]);
                         use[inst->dst.index] = ip;
                 }