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vc4: Turn a SEL_X_Y(x, 0) into SEL_X_0(x).

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This may reduce register pressure and uniform counts.  Drops a bunch of 0
uniform loads on vs-temp-array-mat4-index-col-row-wr.shader_test, which is
failing to register allocate.
This commit is contained in:
Eric Anholt 2014-09-24 21:37:12 -07:00
parent 730267eb23
commit 3311513041
1 changed files with 61 additions and 14 deletions
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75
src/gallium/drivers/vc4/vc4_opt_algebraic.c
View file

@ -34,39 +34,86 @@
#include "vc4_qir.h"
static bool debug;
static void
dump_from(struct qinst *inst)
{
if (!debug)
return;
fprintf(stderr, "optimizing: ");
qir_dump_inst(inst);
fprintf(stderr, "\n");
}
static void
dump_to(struct qinst *inst)
{
if (!debug)
return;
fprintf(stderr, "to: ");
qir_dump_inst(inst);
fprintf(stderr, "\n");
}
static struct qreg
follow_movs(struct qinst **defs, struct qreg reg)
{
while (reg.file == QFILE_TEMP && defs[reg.index]->op == QOP_MOV)
reg = defs[reg.index]->src[0];
return reg;
}
static bool
is_zero(struct vc4_compile *c, struct qinst **defs, struct qreg reg)
{
reg = follow_movs(defs, reg);
return (reg.file == QFILE_UNIF &&
c->uniform_contents[reg.index] == QUNIFORM_CONSTANT &&
c->uniform_data[reg.index] == 0);
}
bool
qir_opt_algebraic(struct vc4_compile *c)
{
bool progress = false;
struct simple_node *node;
bool debug = false;
struct qinst *defs[c->num_temps];
foreach(node, &c->instructions) {
struct qinst *inst = (struct qinst *)node;
if (inst->dst.file == QFILE_TEMP)
defs[inst->dst.index] = inst;
switch (inst->op) {
case QOP_SEL_X_Y_ZS:
case QOP_SEL_X_Y_ZC:
case QOP_SEL_X_Y_NS:
case QOP_SEL_X_Y_NC:
/* Turn "dst = (sf == x) ? a : a)" into "dst = a" */
if (qir_reg_equals(inst->src[0], inst->src[1])) {
if (debug) {
fprintf(stderr, "optimizing: ");
qir_dump_inst(inst);
fprintf(stderr, "\n");
}
/* Turn "dst = (sf == x) ? a : a)" into
* "dst = a"
*/
dump_from(inst);
inst->op = QOP_MOV;
inst->src[0] = inst->src[1];
inst->src[1] = c->undef;
progress = true;
if (debug) {
fprintf(stderr, "to: ");
qir_dump_inst(inst);
fprintf(stderr, "\n");
}
dump_to(inst);
} else if (is_zero(c, defs, inst->src[1])) {
/* Replace references to a 0 uniform value
* with the SEL_X_0 equivalent.
*/
dump_from(inst);
inst->op -= (QOP_SEL_X_Y_ZS - QOP_SEL_X_0_ZS);
inst->src[1] = c->undef;
progress = true;
dump_to(inst);
}
break;