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authorAlyssa Rosenzweig <[email protected]>2019-08-30 10:53:13 -0700
committerAlyssa Rosenzweig <[email protected]>2019-08-30 15:50:26 -0700
commitcc2ba8efe96f2b44a6dc3d1e0b06c3a1ee9b8f50 (patch)
tree2d3b481215dee4cc696e6294ef47ca4b6818e118
parent19bceb5812cf3056c1b5ffb3c372d3f8b9872e26 (diff)
pan/midgard: Add scheduling barriers
Scheduling occurs on a per-block basis, strongly assuming that a given block contains at most a single branch. This does not always map to the source NIR control flow, particularly when discard intrinsics are involved. The solution is to allow scheduling barriers, which will terminate a block early in code generation and open a new block. To facilitate this, we need to move some post-block processing to a new pass, rather than relying hackily on the current_block pointer. This allows us to cleanup some logic analyzing branches in other parts of the driver us well, now that the MIR is much more well-formed. Signed-off-by: Alyssa Rosenzweig <[email protected]>
-rw-r--r--src/panfrost/midgard/midgard_compile.c80
1 files changed, 42 insertions, 38 deletions
diff --git a/src/panfrost/midgard/midgard_compile.c b/src/panfrost/midgard/midgard_compile.c
index 6317e886dcc..2223f92f1bd 100644
--- a/src/panfrost/midgard/midgard_compile.c
+++ b/src/panfrost/midgard/midgard_compile.c
@@ -75,6 +75,20 @@ midgard_is_branch_unit(unsigned unit)
return (unit == ALU_ENAB_BRANCH) || (unit == ALU_ENAB_BR_COMPACT);
}
+static midgard_block *
+create_empty_block(compiler_context *ctx)
+{
+ midgard_block *blk = rzalloc(ctx, midgard_block);
+
+ blk->predecessors = _mesa_set_create(blk,
+ _mesa_hash_pointer,
+ _mesa_key_pointer_equal);
+
+ blk->source_id = ctx->block_source_count++;
+
+ return blk;
+}
+
static void
midgard_block_add_successor(midgard_block *block, midgard_block *successor)
{
@@ -94,6 +108,19 @@ midgard_block_add_successor(midgard_block *block, midgard_block *successor)
_mesa_set_add(successor->predecessors, block);
}
+static void
+schedule_barrier(compiler_context *ctx)
+{
+ midgard_block *temp = ctx->after_block;
+ ctx->after_block = create_empty_block(ctx);
+ ctx->block_count++;
+ list_addtail(&ctx->after_block->link, &ctx->blocks);
+ list_inithead(&ctx->after_block->instructions);
+ midgard_block_add_successor(ctx->current_block, ctx->after_block);
+ ctx->current_block = ctx->after_block;
+ ctx->after_block = temp;
+}
+
/* Helpers to generate midgard_instruction's using macro magic, since every
* driver seems to do it that way */
@@ -1431,6 +1458,8 @@ emit_intrinsic(compiler_context *ctx, nir_intrinsic_instr *instr)
discard.src[0] = nir_src_index(ctx, &instr->src[0]);
emit_mir_instruction(ctx, discard);
+ schedule_barrier(ctx);
+
break;
}
@@ -1498,6 +1527,7 @@ emit_intrinsic(compiler_context *ctx, nir_intrinsic_instr *instr)
midgard_instruction move = v_mov(SSA_FIXED_REGISTER(0), blank_alu_src, reg);
emit_mir_instruction(ctx, move);
+ schedule_barrier(ctx);
} else if (ctx->stage == MESA_SHADER_VERTEX) {
midgard_instruction ins = m_ld_attr_32(reg, offset);
ins.load_store.arg_1 = 0x1E;
@@ -1938,9 +1968,9 @@ emit_instr(compiler_context *ctx, struct nir_instr *instr)
}
static void
-inline_alu_constants(compiler_context *ctx)
+inline_alu_constants(compiler_context *ctx, midgard_block *block)
{
- mir_foreach_instr(ctx, alu) {
+ mir_foreach_instr_in_block(block, alu) {
/* Other instructions cannot inline constants */
if (alu->type != TAG_ALU_4) continue;
@@ -2023,9 +2053,9 @@ mir_contrapositive(midgard_alu_op op)
* sometimes a performance boost */
static void
-embedded_to_inline_constant(compiler_context *ctx)
+embedded_to_inline_constant(compiler_context *ctx, midgard_block *block)
{
- mir_foreach_instr(ctx, ins) {
+ mir_foreach_instr_in_block(block, ins) {
if (!ins->has_constants) continue;
if (ins->has_inline_constant) continue;
@@ -2173,19 +2203,8 @@ midgard_opt_cull_dead_branch(compiler_context *ctx, midgard_block *block)
mir_foreach_instr_in_block_safe(block, ins) {
if (!midgard_is_branch_unit(ins->unit)) continue;
- /* We ignore prepacked branches since the fragment epilogue is
- * just generally special */
- if (ins->prepacked_branch) continue;
-
- /* Discards are similarly special and may not correspond to the
- * end of a block */
-
- if (ins->branch.target_type == TARGET_DISCARD) continue;
-
- if (branched) {
- /* We already branched, so this is dead */
+ if (branched)
mir_remove_instruction(ins);
- }
branched = true;
}
@@ -2261,20 +2280,6 @@ emit_fragment_epilogue(compiler_context *ctx)
}
static midgard_block *
-create_empty_block(compiler_context *ctx)
-{
- midgard_block *blk = rzalloc(ctx, midgard_block);
-
- blk->predecessors = _mesa_set_create(blk,
- _mesa_hash_pointer,
- _mesa_key_pointer_equal);
-
- blk->source_id = ctx->block_source_count++;
-
- return blk;
-}
-
-static midgard_block *
emit_block(compiler_context *ctx, nir_block *block)
{
midgard_block *this_block = ctx->after_block;
@@ -2300,14 +2305,6 @@ emit_block(compiler_context *ctx, nir_block *block)
++ctx->instruction_count;
}
- inline_alu_constants(ctx);
- midgard_opt_promote_fmov(ctx, ctx->current_block);
- embedded_to_inline_constant(ctx);
-
- /* Allow the next control flow to access us retroactively, for
- * branching etc */
- ctx->current_block = this_block;
-
return this_block;
}
@@ -2595,6 +2592,13 @@ midgard_compile_shader_nir(struct midgard_screen *screen, nir_shader *nir, midga
util_dynarray_init(compiled, NULL);
+ /* Per-block lowering before opts */
+
+ mir_foreach_block(ctx, block) {
+ inline_alu_constants(ctx, block);
+ midgard_opt_promote_fmov(ctx, block);
+ embedded_to_inline_constant(ctx, block);
+ }
/* MIR-level optimizations */
bool progress = false;