[Mesa-dev] [PATCH 3/7] gallium/radeon: simplify if/else/endif blocks

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

In particular, we no longer emit an else block when there is no ELSE
instruction.
---
 src/gallium/drivers/radeon/radeon_llvm.h           |  4 +--
 .../drivers/radeon/radeon_setup_tgsi_llvm.c        | 39 ++++++++++------------
 2 files changed, 18 insertions(+), 25 deletions(-)

diff --git a/src/gallium/drivers/radeon/radeon_llvm.h b/src/gallium/drivers/radeon/radeon_llvm.h
index f508d32..58193db 100644
--- a/src/gallium/drivers/radeon/radeon_llvm.h
+++ b/src/gallium/drivers/radeon/radeon_llvm.h
@@ -34,23 +34,21 @@
 
 #define RADEON_LLVM_MAX_INPUT_SLOTS 32
 #define RADEON_LLVM_MAX_INPUTS 32 * 4
 #define RADEON_LLVM_MAX_OUTPUTS 32 * 4
 
 #define RADEON_LLVM_INITIAL_CF_DEPTH 4
 
 #define RADEON_LLVM_MAX_SYSTEM_VALUES 4
 
 struct radeon_llvm_branch {
-	LLVMBasicBlockRef endif_block;
-	LLVMBasicBlockRef if_block;
-	LLVMBasicBlockRef else_block;
+	LLVMBasicBlockRef next_block;
 	unsigned has_else;
 };
 
 struct radeon_llvm_loop {
 	LLVMBasicBlockRef loop_block;
 	LLVMBasicBlockRef endloop_block;
 };
 
 struct radeon_llvm_context {
 	struct lp_build_tgsi_soa_context soa;
diff --git a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
index 2f6b7e2..6cae858 100644
--- a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
+++ b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
@@ -871,46 +871,45 @@ static void cont_emit(const struct lp_build_tgsi_action *action,
 	LLVMBuildBr(gallivm->builder, current_loop->loop_block);
 }
 
 static void else_emit(const struct lp_build_tgsi_action *action,
 		      struct lp_build_tgsi_context *bld_base,
 		      struct lp_build_emit_data *emit_data)
 {
 	struct radeon_llvm_context *ctx = radeon_llvm_context(bld_base);
 	struct gallivm_state *gallivm = bld_base->base.gallivm;
 	struct radeon_llvm_branch *current_branch = get_current_branch(ctx);
+	LLVMBasicBlockRef endif_block;
+
+	endif_block = LLVMAppendBasicBlockInContext(gallivm->context,
+						    ctx->main_fn, "ENDIF");
+	emit_default_branch(gallivm->builder, endif_block);
 
-	emit_default_branch(gallivm->builder, current_branch->endif_block);
 	current_branch->has_else = 1;
-	LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->else_block);
-	set_basicblock_name(current_branch->else_block, "else", bld_base->pc);
+	LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->next_block);
+	set_basicblock_name(current_branch->next_block, "else", bld_base->pc);
+
+	current_branch->next_block = endif_block;
 }
 
 static void endif_emit(const struct lp_build_tgsi_action *action,
 		       struct lp_build_tgsi_context *bld_base,
 		       struct lp_build_emit_data *emit_data)
 {
 	struct radeon_llvm_context *ctx = radeon_llvm_context(bld_base);
 	struct gallivm_state *gallivm = bld_base->base.gallivm;
 	struct radeon_llvm_branch *current_branch = get_current_branch(ctx);
 
-	emit_default_branch(gallivm->builder, current_branch->endif_block);
+	emit_default_branch(gallivm->builder, current_branch->next_block);
+	LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->next_block);
+	set_basicblock_name(current_branch->next_block, "endif", bld_base->pc);
 
-	/* Need to fixup an empty else block if there was no ELSE opcode. */
-	if (!LLVMGetBasicBlockTerminator(current_branch->else_block)) {
-		LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->else_block);
-		LLVMBuildBr(gallivm->builder, current_branch->endif_block);
-		set_basicblock_name(current_branch->else_block, "empty_else", bld_base->pc);
-	}
-
-	LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->endif_block);
-	set_basicblock_name(current_branch->endif_block, "endif", bld_base->pc);
 	ctx->branch_depth--;
 }
 
 static void endloop_emit(const struct lp_build_tgsi_action *action,
 			 struct lp_build_tgsi_context *bld_base,
 			 struct lp_build_emit_data *emit_data)
 {
 	struct radeon_llvm_context *ctx = radeon_llvm_context(bld_base);
 	struct gallivm_state *gallivm = bld_base->base.gallivm;
 	struct radeon_llvm_loop *current_loop = get_current_loop(ctx);
@@ -922,47 +921,43 @@ static void endloop_emit(const struct lp_build_tgsi_action *action,
 	ctx->loop_depth--;
 }
 
 static void if_cond_emit(const struct lp_build_tgsi_action *action,
 			 struct lp_build_tgsi_context *bld_base,
 			 struct lp_build_emit_data *emit_data,
 			 LLVMValueRef cond)
 {
 	struct radeon_llvm_context *ctx = radeon_llvm_context(bld_base);
 	struct gallivm_state *gallivm = bld_base->base.gallivm;
-	LLVMBasicBlockRef if_block, else_block, endif_block;
+	LLVMBasicBlockRef if_block, else_block;
 
-	endif_block = LLVMAppendBasicBlockInContext(gallivm->context,
-						ctx->main_fn, "ENDIF");
+	else_block = LLVMAppendBasicBlockInContext(gallivm->context,
+						   ctx->main_fn, "ELSE");
 	if_block = LLVMInsertBasicBlockInContext(gallivm->context,
-						endif_block, "IF");
-	else_block = LLVMInsertBasicBlockInContext(gallivm->context,
-						endif_block, "ELSE");
+						else_block, "IF");
 	set_basicblock_name(if_block, "if", bld_base->pc);
 	LLVMBuildCondBr(gallivm->builder, cond, if_block, else_block);
 	LLVMPositionBuilderAtEnd(gallivm->builder, if_block);
 
 	if (++ctx->branch_depth > ctx->branch_depth_max) {
 		unsigned new_max = ctx->branch_depth_max << 1;
 
 		if (!new_max)
 			new_max = RADEON_LLVM_INITIAL_CF_DEPTH;
 
 		ctx->branch = REALLOC(ctx->branch, ctx->branch_depth_max *
 				      sizeof(ctx->branch[0]),
 				      new_max * sizeof(ctx->branch[0]));
 		ctx->branch_depth_max = new_max;
 	}
 
-	ctx->branch[ctx->branch_depth - 1].endif_block = endif_block;
-	ctx->branch[ctx->branch_depth - 1].if_block = if_block;
-	ctx->branch[ctx->branch_depth - 1].else_block = else_block;
+	ctx->branch[ctx->branch_depth - 1].next_block = else_block;
 	ctx->branch[ctx->branch_depth - 1].has_else = 0;
 }
 
 static void if_emit(const struct lp_build_tgsi_action *action,
 		    struct lp_build_tgsi_context *bld_base,
 		    struct lp_build_emit_data *emit_data)
 {
 	struct gallivm_state *gallivm = bld_base->base.gallivm;
 	LLVMValueRef cond;
 
-- 
2.7.4