[Mesa-dev] [PATCH] radv: do not load vertex attributes that are not provided by the pipeline

[Samuel Pitoiset]

Per the Vulkan spec this is definitely invalid but X4 Foundations
does that and it ends up by hanging the GPU.

Found while enabling validation layers with the game. The issue
will be reported to the developers.

Cc: "19.0" mesa-stable at lists.freedesktop.org
Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
---

This is a backport for staging/19.0 *only*!

 src/amd/vulkan/radv_nir_to_llvm.c | 30 ++++++++++++++++++++++++++----
 src/amd/vulkan/radv_pipeline.c    |  3 +++
 src/amd/vulkan/radv_private.h     |  1 +
 src/amd/vulkan/radv_shader.h      |  3 +++
 4 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/amd/vulkan/radv_nir_to_llvm.c b/src/amd/vulkan/radv_nir_to_llvm.c
index bb8ebca0dab..fba08f29134 100644
--- a/src/amd/vulkan/radv_nir_to_llvm.c
+++ b/src/amd/vulkan/radv_nir_to_llvm.c
@@ -2027,10 +2027,32 @@ handle_vs_input_decl(struct radv_shader_context *ctx,
 
 		t_list = ac_build_load_to_sgpr(&ctx->ac, t_list_ptr, t_offset);
 
-		input = ac_build_buffer_load_format(&ctx->ac, t_list,
-						    buffer_index,
-						    ctx->ac.i32_0,
-						    num_channels, false, true);
+		if (ctx->options->key.vs.vertex_attribute_provided & (1u << attrib_index)) {
+			input = ac_build_buffer_load_format(&ctx->ac, t_list,
+							    buffer_index,
+							    ctx->ac.i32_0,
+							    num_channels, false, true);
+		} else {
+			/* Per the Vulkan spec, it's invalid to consume vertex
+			 * attributes that are not provided by the pipeline but
+			 * some (invalid) apps appear to do that. Fill the
+			 * input array with (eg. (0, 0, 0, 1)) to workaround
+			 * the problem and to avoid possible GPU hangs.
+			 */
+			LLVMValueRef chan[4];
+
+			/* The input_usage mask might be 0 if input variables
+			 * are not removed by the compiler.
+			 */
+			num_channels = CLAMP(num_channels, 1, 4);
+
+			for (unsigned i = 0; i < num_channels; i++) {
+				chan[i] = i == 3 ? ctx->ac.i32_1 : ctx->ac.i32_0;
+				chan[i] = ac_to_float(&ctx->ac, chan[i]);
+			}
+
+			input = ac_build_gather_values(&ctx->ac, chan, num_channels);
+		}
 
 		input = ac_build_expand_to_vec4(&ctx->ac, input, num_channels);
 
diff --git a/src/amd/vulkan/radv_pipeline.c b/src/amd/vulkan/radv_pipeline.c
index 61bdfc5cd2d..91f468910f1 100644
--- a/src/amd/vulkan/radv_pipeline.c
+++ b/src/amd/vulkan/radv_pipeline.c
@@ -1922,6 +1922,8 @@ radv_generate_graphics_pipeline_key(struct radv_pipeline *pipeline,
 			}
 			key.vertex_alpha_adjust |= adjust << (2 * location);
 		}
+
+		key.vertex_attribute_provided |= 1 << location;
 	}
 
 	if (pCreateInfo->pTessellationState)
@@ -1950,6 +1952,7 @@ radv_fill_shader_keys(struct radv_shader_variant_key *keys,
 {
 	keys[MESA_SHADER_VERTEX].vs.instance_rate_inputs = key->instance_rate_inputs;
 	keys[MESA_SHADER_VERTEX].vs.alpha_adjust = key->vertex_alpha_adjust;
+	keys[MESA_SHADER_VERTEX].vs.vertex_attribute_provided = key->vertex_attribute_provided;
 	for (unsigned i = 0; i < MAX_VERTEX_ATTRIBS; ++i)
 		keys[MESA_SHADER_VERTEX].vs.instance_rate_divisors[i] = key->instance_rate_divisors[i];
 
diff --git a/src/amd/vulkan/radv_private.h b/src/amd/vulkan/radv_private.h
index aaf057ea919..cd025cd5c4c 100644
--- a/src/amd/vulkan/radv_private.h
+++ b/src/amd/vulkan/radv_private.h
@@ -365,6 +365,7 @@ struct radv_pipeline_cache {
 struct radv_pipeline_key {
 	uint32_t instance_rate_inputs;
 	uint32_t instance_rate_divisors[MAX_VERTEX_ATTRIBS];
+	uint32_t vertex_attribute_provided;
 	uint64_t vertex_alpha_adjust;
 	unsigned tess_input_vertices;
 	uint32_t col_format;
diff --git a/src/amd/vulkan/radv_shader.h b/src/amd/vulkan/radv_shader.h
index 31839c3a85e..f6f9dd2bbf1 100644
--- a/src/amd/vulkan/radv_shader.h
+++ b/src/amd/vulkan/radv_shader.h
@@ -66,6 +66,9 @@ struct radv_vs_variant_key {
 	uint32_t instance_rate_inputs;
 	uint32_t instance_rate_divisors[MAX_VERTEX_ATTRIBS];
 
+	/* Mask of vertex attributes that are provided by the pipeline. */
+	uint32_t vertex_attribute_provided;
+
 	/* For 2_10_10_10 formats the alpha is handled as unsigned by pre-vega HW.
 	 * so we may need to fix it up. */
 	uint64_t alpha_adjust;
-- 
2.21.0