radv/llvm: implement radv_enable_mrt_output_nan_fixup workaround

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5359>

diff --git a/src/amd/vulkan/radv_nir_to_llvm.c b/src/amd/vulkan/radv_nir_to_llvm.c
index 4dd6ded5d029e62bfdb17f2ed1da99541e97608e..e8ad6d83df3c0276e55752ee143850895dd2613a 100644 (file)
--- a/src/amd/vulkan/radv_nir_to_llvm.c
+++ b/src/amd/vulkan/radv_nir_to_llvm.c
@@ -1553,6 +1553,30 @@ si_llvm_init_export_args(struct radv_shader_context *ctx,
                        break;
                }
 
+               /* Replace NaN by zero (only 32-bit) to fix game bugs if
+                * requested.
+                */
+               if (ctx->args->options->enable_mrt_output_nan_fixup &&
+                   !is_16bit &&
+                   (col_format == V_028714_SPI_SHADER_32_R ||
+                    col_format == V_028714_SPI_SHADER_32_GR ||
+                    col_format == V_028714_SPI_SHADER_32_AR ||
+                    col_format == V_028714_SPI_SHADER_32_ABGR ||
+                    col_format == V_028714_SPI_SHADER_FP16_ABGR)) {
+                       for (unsigned i = 0; i < 4; i++) {
+                               LLVMValueRef args[2] = {
+                                       values[i],
+                                       LLVMConstInt(ctx->ac.i32, S_NAN | Q_NAN, false)
+                               };
+                               LLVMValueRef isnan =
+                                       ac_build_intrinsic(&ctx->ac, "llvm.amdgcn.class.f32", ctx->ac.i1,
+                                                          args, 2, AC_FUNC_ATTR_READNONE);
+                               values[i] = LLVMBuildSelect(ctx->ac.builder, isnan,
+                                                           ctx->ac.f32_0,
+                                                           values[i], "");
+                       }
+               }
+
                /* Pack f16 or norm_i16/u16. */
                if (packf) {
                        for (chan = 0; chan < 2; chan++) {