r600g: use a select to handle front/back color in llvm

Reviewed-by: Tom Stellard <[email protected]>

2 files changed, 44 insertions, 5 deletions

diff --git a/src/gallium/drivers/r600/r600_llvm.c b/src/gallium/drivers/r600/r600_llvm.c
index 71ea5781220..c6e60afaba3 100644
--- a/src/gallium/drivers/r600/r600_llvm.c
+++ b/src/gallium/drivers/r600/r600_llvm.c
@@ -86,6 +86,42 @@ static void llvm_load_input(
 				"llvm.R600.load.input",
 				ctx->soa.bld_base.base.elem_type, &reg, 1,
 				LLVMReadNoneAttribute);
+				
+		if (decl->Semantic.Name == TGSI_SEMANTIC_COLOR && ctx->two_side) {
+			unsigned back_reg = ctx->r600_inputs[input_index]
+				.potential_back_facing_reg;
+			unsigned back_soa_index = radeon_llvm_reg_index_soa(
+				ctx->r600_inputs[back_reg].gpr
+				, chan);
+			LLVMValueRef backcolor_reg = lp_build_const_int32(
+				ctx->soa.bld_base.base.gallivm,
+				back_soa_index);
+			LLVMValueRef backcolor = build_intrinsic(
+				ctx->soa.bld_base.base.gallivm->builder,
+				"llvm.R600.load.input",
+				ctx->soa.bld_base.base.elem_type, &backcolor_reg, 1,
+				LLVMReadNoneAttribute);
+			LLVMValueRef face_reg = lp_build_const_int32(
+				ctx->soa.bld_base.base.gallivm,
+				ctx->face_input * 4);
+			LLVMValueRef face = build_intrinsic(
+				ctx->soa.bld_base.base.gallivm->builder,
+				"llvm.R600.load.input",
+				ctx->soa.bld_base.base.elem_type,
+				&face_reg, 1,
+				LLVMReadNoneAttribute);
+			LLVMValueRef is_face_positive = LLVMBuildFCmp(
+				ctx->soa.bld_base.base.gallivm->builder,
+				LLVMRealUGT, face, 
+				lp_build_const_float(ctx->soa.bld_base.base.gallivm, 0.0f),
+				"");
+			ctx->inputs[soa_index] = LLVMBuildSelect(
+				ctx->soa.bld_base.base.gallivm->builder,
+				is_face_positive,
+				ctx->inputs[soa_index],
+				backcolor,
+				"");
+		}
 	}
 }
 
diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
index 0c585de8263..daa50823448 100644
--- a/src/gallium/drivers/r600/r600_shader.c
+++ b/src/gallium/drivers/r600/r600_shader.c
@@ -1128,7 +1128,7 @@ static int tgsi_split_literal_constant(struct r600_shader_ctx *ctx)
 	return 0;
 }
 
-static int process_twoside_color_inputs(struct r600_shader_ctx *ctx)
+static int process_twoside_color_inputs(struct r600_shader_ctx *ctx, unsigned use_llvm)
 {
 	int i, r, count = ctx->shader->ninput;
 
@@ -1139,9 +1139,12 @@ static int process_twoside_color_inputs(struct r600_shader_ctx *ctx)
 				if ((r = evergreen_interp_input(ctx, back_facing_reg)))
 					return r;
 			}
-			r = select_twoside_color(ctx, i, back_facing_reg);
-			if (r)
-				return r;
+			
+			if (!use_llvm) {
+				r = select_twoside_color(ctx, i, back_facing_reg);
+				if (r)
+					return r;
+			}
 		}
 	}
 	return 0;
@@ -1402,7 +1405,7 @@ static int r600_shader_from_tgsi(struct r600_screen *rscreen,
 	}
 
 	if (shader->two_side && ctx.colors_used) {
-		if ((r = process_twoside_color_inputs(&ctx)))
+		if ((r = process_twoside_color_inputs(&ctx, use_llvm)))
 			return r;
 	}