We reshuffle the existing "dead move elimination" pass into a generic
dead code elimination layer, fixing bugs incurred with looping in the
process.
Signed-off-by: Alyssa Rosenzweig <aly...@rosenzweig.io>
---
.../panfrost/midgard/midgard_compile.c | 25 ++++++++-----------
1 file changed, 10 insertions(+), 15 deletions(-)
diff --git a/src/gallium/drivers/panfrost/midgard/midgard_compile.c
b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
index 317f25762dc..7fe5b98b0ab 100644
--- a/src/gallium/drivers/panfrost/midgard/midgard_compile.c
+++ b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
@@ -643,8 +643,6 @@ print_mir_block(midgard_block *block)
printf("}\n");
}
-
-
static void
attach_constants(compiler_context *ctx, midgard_instruction *ins, void
*constants, int name)
{
@@ -3045,26 +3043,18 @@ map_ssa_to_alias(compiler_context *ctx, int *ref)
}
}
-#define AS_SRC(to, u) \
- int q##to = ins->alu.src2; \
- midgard_vector_alu_src *to = (midgard_vector_alu_src *) &q##to;
-
-/* Removing unused moves is necessary to clean up the texture pipeline results.
- *
- * To do so, we find moves in the MIR. We check if their destination is live
later. If it's not, the move is redundant. */
+/* Basic dead code elimination on the MIR itself, which cleans up e.g. the
+ * texture pipeline */
static void
-midgard_eliminate_orphan_moves(compiler_context *ctx, midgard_block *block)
+midgard_opt_dead_code_eliminate(compiler_context *ctx, midgard_block *block)
{
mir_foreach_instr_in_block_safe(block, ins) {
if (ins->type != TAG_ALU_4) continue;
-
- if (ins->alu.op != midgard_alu_op_fmov) continue;
+ if (ins->compact_branch) continue;
if (ins->ssa_args.dest >= SSA_FIXED_MINIMUM) continue;
-
if (midgard_is_pinned(ctx, ins->ssa_args.dest)) continue;
-
if (is_live_after(ctx, block, ins, ins->ssa_args.dest))
continue;
mir_remove_instruction(ins);
@@ -3321,7 +3311,6 @@ emit_block(compiler_context *ctx, nir_block *block)
actualise_ssa_to_alias(ctx);
midgard_emit_store(ctx, this_block);
- midgard_eliminate_orphan_moves(ctx, this_block);
midgard_pair_load_store(ctx, this_block);
/* Append fragment shader epilogue (value writeout) */
@@ -3608,6 +3597,12 @@ midgard_compile_shader_nir(nir_shader *nir,
midgard_program *program, bool is_bl
util_dynarray_init(compiled, NULL);
+ /* Peephole optimizations */
+
+ mir_foreach_block(ctx, block) {
+ midgard_opt_dead_code_eliminate(ctx, block);
+ }
+
/* Schedule! */
schedule_program(ctx);
--
2.20.1
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