aco: Extract uniform if handling to separate functions.

Currently we only use this for uniform ifs that come from NIR,
but we are going to need to use it with some NGG parts as well.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3576>

diff --git a/src/amd/compiler/aco_instruction_selection.cpp b/src/amd/compiler/aco_instruction_selection.cpp
index 6a63d5d..8bc0e58 100644 (file)
--- a/src/amd/compiler/aco_instruction_selection.cpp
+++ b/src/amd/compiler/aco_instruction_selection.cpp
@@ -85,6 +85,7 @@ struct if_context {
 
    unsigned BB_if_idx;
    unsigned invert_idx;
+   bool uniform_has_then_branch;
    bool then_branch_divergent;
    Block BB_invert;
    Block BB_endif;
@@ -9305,11 +9306,98 @@ static void end_divergent_if(isel_context *ctx, if_context *ic)
    }
 }
 
+static void begin_uniform_if_then(isel_context *ctx, if_context *ic, Temp cond)
+{
+   assert(cond.regClass() == s1);
+
+   append_logical_end(ctx->block);
+   ctx->block->kind |= block_kind_uniform;
+
+   aco_ptr<Pseudo_branch_instruction> branch;
+   aco_opcode branch_opcode = aco_opcode::p_cbranch_z;
+   branch.reset(create_instruction<Pseudo_branch_instruction>(branch_opcode, Format::PSEUDO_BRANCH, 1, 0));
+   branch->operands[0] = Operand(cond);
+   branch->operands[0].setFixed(scc);
+   ctx->block->instructions.emplace_back(std::move(branch));
+
+   ic->BB_if_idx = ctx->block->index;
+   ic->BB_endif = Block();
+   ic->BB_endif.loop_nest_depth = ctx->cf_info.loop_nest_depth;
+   ic->BB_endif.kind |= ctx->block->kind & block_kind_top_level;
+
+   ctx->cf_info.has_branch = false;
+   ctx->cf_info.parent_loop.has_divergent_branch = false;
+
+   /** emit then block */
+   Block* BB_then = ctx->program->create_and_insert_block();
+   BB_then->loop_nest_depth = ctx->cf_info.loop_nest_depth;
+   add_edge(ic->BB_if_idx, BB_then);
+   append_logical_start(BB_then);
+   ctx->block = BB_then;
+}
+
+static void begin_uniform_if_else(isel_context *ctx, if_context *ic)
+{
+   Block *BB_then = ctx->block;
+
+   ic->uniform_has_then_branch = ctx->cf_info.has_branch;
+   ic->then_branch_divergent = ctx->cf_info.parent_loop.has_divergent_branch;
+
+   if (!ic->uniform_has_then_branch) {
+      append_logical_end(BB_then);
+      /* branch from then block to endif block */
+      aco_ptr<Pseudo_branch_instruction> branch;
+      branch.reset(create_instruction<Pseudo_branch_instruction>(aco_opcode::p_branch, Format::PSEUDO_BRANCH, 0, 0));
+      BB_then->instructions.emplace_back(std::move(branch));
+      add_linear_edge(BB_then->index, &ic->BB_endif);
+      if (!ic->then_branch_divergent)
+         add_logical_edge(BB_then->index, &ic->BB_endif);
+      BB_then->kind |= block_kind_uniform;
+   }
+
+   ctx->cf_info.has_branch = false;
+   ctx->cf_info.parent_loop.has_divergent_branch = false;
+
+   /** emit else block */
+   Block* BB_else = ctx->program->create_and_insert_block();
+   BB_else->loop_nest_depth = ctx->cf_info.loop_nest_depth;
+   add_edge(ic->BB_if_idx, BB_else);
+   append_logical_start(BB_else);
+   ctx->block = BB_else;
+}
+
+static void end_uniform_if(isel_context *ctx, if_context *ic)
+{
+   Block *BB_else = ctx->block;
+
+   if (!ctx->cf_info.has_branch) {
+      append_logical_end(BB_else);
+      /* branch from then block to endif block */
+      aco_ptr<Pseudo_branch_instruction> branch;
+      branch.reset(create_instruction<Pseudo_branch_instruction>(aco_opcode::p_branch, Format::PSEUDO_BRANCH, 0, 0));
+      BB_else->instructions.emplace_back(std::move(branch));
+      add_linear_edge(BB_else->index, &ic->BB_endif);
+      if (!ctx->cf_info.parent_loop.has_divergent_branch)
+         add_logical_edge(BB_else->index, &ic->BB_endif);
+      BB_else->kind |= block_kind_uniform;
+   }
+
+   ctx->cf_info.has_branch &= ic->uniform_has_then_branch;
+   ctx->cf_info.parent_loop.has_divergent_branch &= ic->then_branch_divergent;
+
+   /** emit endif merge block */
+   if (!ctx->cf_info.has_branch) {
+      ctx->block = ctx->program->insert_block(std::move(ic->BB_endif));
+      append_logical_start(ctx->block);
+   }
+}
+
 static bool visit_if(isel_context *ctx, nir_if *if_stmt)
 {
    Temp cond = get_ssa_temp(ctx, if_stmt->condition.ssa);
    Builder bld(ctx->program, ctx->block);
    aco_ptr<Pseudo_branch_instruction> branch;
+   if_context ic;
 
    if (!ctx->divergent_vals[if_stmt->condition.ssa->index]) { /* uniform condition */
       /**
@@ -9327,77 +9415,19 @@ static bool visit_if(isel_context *ctx, nir_if *if_stmt)
        *    to the loop exit/entry block. Otherwise, it branches to the next
        *    merge block.
        **/
-      append_logical_end(ctx->block);
-      ctx->block->kind |= block_kind_uniform;
 
-      /* emit branch */
-      assert(cond.regClass() == bld.lm);
       // TODO: in a post-RA optimizer, we could check if the condition is in VCC and omit this instruction
+      assert(cond.regClass() == ctx->program->lane_mask);
       cond = bool_to_scalar_condition(ctx, cond);
 
-      branch.reset(create_instruction<Pseudo_branch_instruction>(aco_opcode::p_cbranch_z, Format::PSEUDO_BRANCH, 1, 0));
-      branch->operands[0] = Operand(cond);
-      branch->operands[0].setFixed(scc);
-      ctx->block->instructions.emplace_back(std::move(branch));
-
-      unsigned BB_if_idx = ctx->block->index;
-      Block BB_endif = Block();
-      BB_endif.loop_nest_depth = ctx->cf_info.loop_nest_depth;
-      BB_endif.kind |= ctx->block->kind & block_kind_top_level;
-
-      /** emit then block */
-      Block* BB_then = ctx->program->create_and_insert_block();
-      BB_then->loop_nest_depth = ctx->cf_info.loop_nest_depth;
-      add_edge(BB_if_idx, BB_then);
-      append_logical_start(BB_then);
-      ctx->block = BB_then;
+      begin_uniform_if_then(ctx, &ic, cond);
       visit_cf_list(ctx, &if_stmt->then_list);
-      BB_then = ctx->block;
-      bool then_branch = ctx->cf_info.has_branch;
-      bool then_branch_divergent = ctx->cf_info.parent_loop.has_divergent_branch;
-
-      if (!then_branch) {
-         append_logical_end(BB_then);
-         /* branch from then block to endif block */
-         branch.reset(create_instruction<Pseudo_branch_instruction>(aco_opcode::p_branch, Format::PSEUDO_BRANCH, 0, 0));
-         BB_then->instructions.emplace_back(std::move(branch));
-         add_linear_edge(BB_then->index, &BB_endif);
-         if (!then_branch_divergent)
-            add_logical_edge(BB_then->index, &BB_endif);
-         BB_then->kind |= block_kind_uniform;
-      }
-
-      ctx->cf_info.has_branch = false;
-      ctx->cf_info.parent_loop.has_divergent_branch = false;
 
-      /** emit else block */
-      Block* BB_else = ctx->program->create_and_insert_block();
-      BB_else->loop_nest_depth = ctx->cf_info.loop_nest_depth;
-      add_edge(BB_if_idx, BB_else);
-      append_logical_start(BB_else);
-      ctx->block = BB_else;
+      begin_uniform_if_else(ctx, &ic);
       visit_cf_list(ctx, &if_stmt->else_list);
-      BB_else = ctx->block;
 
-      if (!ctx->cf_info.has_branch) {
-         append_logical_end(BB_else);
-         /* branch from then block to endif block */
-         branch.reset(create_instruction<Pseudo_branch_instruction>(aco_opcode::p_branch, Format::PSEUDO_BRANCH, 0, 0));
-         BB_else->instructions.emplace_back(std::move(branch));
-         add_linear_edge(BB_else->index, &BB_endif);
-         if (!ctx->cf_info.parent_loop.has_divergent_branch)
-            add_logical_edge(BB_else->index, &BB_endif);
-         BB_else->kind |= block_kind_uniform;
-      }
-
-      ctx->cf_info.has_branch &= then_branch;
-      ctx->cf_info.parent_loop.has_divergent_branch &= then_branch_divergent;
+      end_uniform_if(ctx, &ic);
 
-      /** emit endif merge block */
-      if (!ctx->cf_info.has_branch) {
-         ctx->block = ctx->program->insert_block(std::move(BB_endif));
-         append_logical_start(ctx->block);
-      }
       return !ctx->cf_info.has_branch;
    } else { /* non-uniform condition */
       /**
@@ -9425,8 +9455,6 @@ static bool visit_if(isel_context *ctx, nir_if *if_stmt)
        * *) Exceptions may be due to break and continue statements within loops
        **/
 
-      if_context ic;
-
       begin_divergent_if_then(ctx, &ic, cond);
       visit_cf_list(ctx, &if_stmt->then_list);