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authorEric Anholt <eric@anholt.net>2011-01-17 18:34:43 -0800
committerEric Anholt <eric@anholt.net>2011-01-18 10:17:34 -0800
commit754b9c5363aa7ae5f47c88c78790b3fe35c07403 (patch)
treef6a82ee02a2f2f7c9a130c394bd35b425ecd5e86 /src
parent5b58b8c579f06edc2e5ead011e2544eadfbfb77a (diff)
ra: Trade off some space to get time efficiency in ra_set_finalize().
Our use of the register allocator in i965 is somewhat unusual. Whereas most architectures would have a smaller set of registers with fewer register classes and reuse that across compilation, we have 1, 2, and 4-register classes (usually) and a variable number up to 128 registers per compile depending on how many setup parameters and push constants are present. As a result, when compiling large numbers of programs (as with glean texCombine going through ff_fragment_shader), we spent much of our CPU time in computing the q[] array. By keeping a separate list of what the conflicts are for a particular reg, we reduce glean texCombine time 17.0% +/- 2.3% (n=5). We don't expect this optimization to be useful for 915, which will have a constant register set, but it would be useful if we were switch to this register allocator for Mesa IR.
Diffstat (limited to 'src')
-rw-r--r--src/mesa/program/register_allocate.c38
1 files changed, 32 insertions, 6 deletions
diff --git a/src/mesa/program/register_allocate.c b/src/mesa/program/register_allocate.c
index ada6e35641..3d8ccb3916 100644
--- a/src/mesa/program/register_allocate.c
+++ b/src/mesa/program/register_allocate.c
@@ -40,6 +40,9 @@
struct ra_reg {
char *name;
GLboolean *conflicts;
+ unsigned int *conflict_list;
+ unsigned int conflict_list_size;
+ unsigned int num_conflicts;
};
struct ra_regs {
@@ -100,16 +103,39 @@ ra_alloc_reg_set(unsigned int count)
for (i = 0; i < count; i++) {
regs->regs[i].conflicts = talloc_zero_array(regs->regs, GLboolean, count);
regs->regs[i].conflicts[i] = GL_TRUE;
+
+ regs->regs[i].conflict_list = talloc_array(regs->regs, unsigned int, 4);
+ regs->regs[i].conflict_list_size = 4;
+ regs->regs[i].conflict_list[0] = i;
+ regs->regs[i].num_conflicts = 1;
}
return regs;
}
+static void
+ra_add_conflict_list(struct ra_regs *regs, unsigned int r1, unsigned int r2)
+{
+ struct ra_reg *reg1 = &regs->regs[r1];
+
+ if (reg1->conflict_list_size == reg1->num_conflicts) {
+ reg1->conflict_list_size *= 2;
+ reg1->conflict_list = talloc_realloc(regs,
+ reg1->conflict_list,
+ unsigned int,
+ reg1->conflict_list_size);
+ }
+ reg1->conflict_list[reg1->num_conflicts++] = r2;
+ reg1->conflicts[r2] = GL_TRUE;
+}
+
void
ra_add_reg_conflict(struct ra_regs *regs, unsigned int r1, unsigned int r2)
{
- regs->regs[r1].conflicts[r2] = GL_TRUE;
- regs->regs[r2].conflicts[r1] = GL_TRUE;
+ if (!regs->regs[r1].conflicts[r2]) {
+ ra_add_conflict_list(regs, r1, r2);
+ ra_add_conflict_list(regs, r2, r1);
+ }
}
unsigned int
@@ -160,15 +186,15 @@ ra_set_finalize(struct ra_regs *regs)
int max_conflicts = 0;
for (rc = 0; rc < regs->count; rc++) {
- unsigned int rb;
int conflicts = 0;
+ int i;
if (!regs->classes[c]->regs[rc])
continue;
- for (rb = 0; rb < regs->count; rb++) {
- if (regs->classes[b]->regs[rb] &&
- regs->regs[rb].conflicts[rc])
+ for (i = 0; i < regs->regs[rc].num_conflicts; i++) {
+ unsigned int rb = regs->regs[rc].conflict_list[i];
+ if (regs->classes[b]->regs[rb])
conflicts++;
}
max_conflicts = MAX2(max_conflicts, conflicts);