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pan/bi: Do copyprop in linear-time 

Per discussion with Daniel Schürmann on IRC about the joys of SSA form
and why you don't actually need use-def chains. Indeed, I didn't. No
shader-db changes, time difference in shader-db is neglible since the
win from this is particularly for large shaders.

Total runtime of
dEQP-GLES31.functional.ssbo.layout.single_struct_array.single_buffer.std430_instance_array
reduced from 1.04s to 0.77s (25%)

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9164>
This commit is contained in:
Alyssa Rosenzweig 2021-02-18 16:21:43 -05:00 committed by Marge Bot
parent 07456bcde2
commit 856b71bef0
1 changed files with 27 additions and 22 deletions
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49
src/panfrost/bifrost/bi_opt_copy_prop.c
View File

@ -24,27 +24,20 @@
#include "compiler.h"
/* A simple scalar-only SSA-based copy-propagation pass. O(N^2) due to the lack
* of use tracking. TODO: better data structures for O(N), TODO: vectors */
/* A simple scalar-only SSA-based copy-propagation pass. TODO: vectors */
static bool
bi_rewrite_scalar_uses(bi_context *ctx, bi_index old, bi_index new)
bi_is_copy(bi_instr *ins)
{
bool progress = false;
return (ins->op == BI_OPCODE_MOV_I32) && bi_is_ssa(ins->dest[0])
&& (bi_is_ssa(ins->src[0]) || ins->src[0].type == BI_INDEX_FAU);
}
bi_foreach_instr_global(ctx, use) {
bi_foreach_src(use, s) {
bi_index src = use->src[s];
bool scalar = (bi_count_read_registers(use, s) == 1);
if (bi_is_word_equiv(src, old) && scalar) {
use->src[s] = bi_replace_index(src, new);
progress = true;
}
}
}
return progress;
static inline unsigned
bi_word_node(bi_index idx)
{
assert(idx.type == BI_INDEX_NORMAL && !idx.reg);
return (idx.value << 2) | idx.offset;
}
bool
@ -52,13 +45,25 @@ bi_opt_copy_prop(bi_context *ctx)
{
bool progress = false;
bi_foreach_instr_global_safe(ctx, ins) {
if (ins->op != BI_OPCODE_MOV_I32) continue;
if (!bi_is_ssa(ins->dest[0])) continue;
if (!(bi_is_ssa(ins->src[0]) || ins->src[0].type == BI_INDEX_FAU)) continue;
bi_index *replacement = calloc(sizeof(bi_index), ((ctx->ssa_alloc + 1) << 2));
progress |= bi_rewrite_scalar_uses(ctx, ins->dest[0], ins->src[0]);
bi_foreach_instr_global_safe(ctx, ins) {
if (bi_is_copy(ins))
replacement[bi_word_node(ins->dest[0])] = ins->src[0];
bi_foreach_src(ins, s) {
bi_index use = ins->src[s];
if (use.type != BI_INDEX_NORMAL || use.reg) continue;
if (bi_count_read_registers(ins, s) != 1) continue;
bi_index repl = replacement[bi_word_node(use)];
if (!bi_is_null(repl))
ins->src[s] = bi_replace_index(ins->src[s], repl);
}
}
free(replacement);
return progress;
}