amd/common: save an instruction in the build_cube_select sequence

Avoid a v_cndmask: the absolute value is free due to input modifiers.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>

diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
index 8c050f3..71468df 100644 (file)
--- a/src/amd/common/ac_llvm_build.c
+++ b/src/amd/common/ac_llvm_build.c
@@ -438,12 +438,13 @@ build_cube_intrinsic(struct ac_llvm_context *ctx,
  * selcoords.ma; i.e., a positive out_ma means that coords is pointed towards
  * the selcoords major axis.
  */
-static void build_cube_select(LLVMBuilderRef builder,
+static void build_cube_select(struct ac_llvm_context *ctx,
                              const struct cube_selection_coords *selcoords,
                              const LLVMValueRef *coords,
                              LLVMValueRef *out_st,
                              LLVMValueRef *out_ma)
 {
+       LLVMBuilderRef builder = ctx->builder;
        LLVMTypeRef f32 = LLVMTypeOf(coords[0]);
        LLVMValueRef is_ma_positive;
        LLVMValueRef sgn_ma;
@@ -480,9 +481,9 @@ static void build_cube_select(LLVMBuilderRef builder,
        /* Select ma */
        tmp = LLVMBuildSelect(builder, is_ma_z, coords[2],
                LLVMBuildSelect(builder, is_ma_y, coords[1], coords[0], ""), "");
-       sgn = LLVMBuildSelect(builder, is_ma_positive,
-               LLVMConstReal(f32, 2.0), LLVMConstReal(f32, -2.0), "");
-       *out_ma = LLVMBuildFMul(builder, tmp, sgn, "");
+       tmp = ac_build_intrinsic(ctx, "llvm.fabs.f32",
+                                ctx->f32, &tmp, 1, AC_FUNC_ATTR_READNONE);
+       *out_ma = LLVMBuildFMul(builder, tmp, LLVMConstReal(f32, 2.0), "");
 }
 
 void
@@ -570,7 +571,7 @@ ac_prepare_cube_coords(struct ac_llvm_context *ctx,
                         * seems awfully quiet about how textureGrad for cube
                         * maps should be handled.
                         */
-                       build_cube_select(builder, &selcoords, &derivs_arg[axis * 3],
+                       build_cube_select(ctx, &selcoords, &derivs_arg[axis * 3],
                                          deriv_st, &deriv_ma);
 
                        deriv_ma = LLVMBuildFMul(builder, deriv_ma, invma, "");