From a08e493a3a4a8a623b82f9414019a8dc5da6d37b Mon Sep 17 00:00:00 2001
From: Hans-Kristian Arntzen <post@arntzen-software.no>
Date: Wed, 16 Jun 2021 16:52:00 +0200
Subject: [PATCH] vkd3d-shader: Add interface for shader workarounds.

Don't really have much of a choice for the short term. :\

Signed-off-by: Hans-Kristian Arntzen <post@arntzen-software.no>
---
 include/vkd3d_shader.h    | 27 +++++++++++++++++++++++++++
 libs/vkd3d-shader/spirv.c | 22 ++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/include/vkd3d_shader.h b/include/vkd3d_shader.h
index 61c1ee17..d902f5b2 100644
--- a/include/vkd3d_shader.h
+++ b/include/vkd3d_shader.h
@@ -284,6 +284,32 @@ enum vkd3d_shader_target_extension
     VKD3D_SHADER_TARGET_EXTENSION_READ_STORAGE_IMAGE_WITHOUT_FORMAT
 };
 
+enum vkd3d_shader_quirk
+{
+    /* If sample or sample_b is used in control flow, force LOD 0.0 (which game should expect anyway).
+     * Works around specific, questionable shaders which rely on this to give sensible results,
+     * since LOD can become garbage on certain implementations, and even on native drivers
+     * the result is implementation defined.
+     * Outside of making this edge case well-defined in Vulkan or hacking driver compilers,
+     * this is the pragmatic solution.
+     * Hoisting gradients is not possible in all cases,
+     * and would not be worth it until it's a widespread problem. */
+    VKD3D_SHADER_QUIRK_FORCE_EXPLICIT_LOD_IN_CONTROL_FLOW = (1 << 0)
+};
+
+struct vkd3d_shader_quirk_hash
+{
+    vkd3d_shader_hash_t shader_hash;
+    uint32_t quirks;
+};
+
+struct vkd3d_shader_quirk_info
+{
+    const struct vkd3d_shader_quirk_hash *hashes;
+    unsigned int num_hashes;
+    uint32_t default_quirks;
+};
+
 struct vkd3d_shader_compile_arguments
 {
     enum vkd3d_shader_target target;
@@ -299,6 +325,7 @@ struct vkd3d_shader_compile_arguments
     unsigned int output_swizzle_count;
 
     uint64_t config_flags;
+    const struct vkd3d_shader_quirk_info *quirks;
 };
 
 enum vkd3d_tessellator_output_primitive
diff --git a/libs/vkd3d-shader/spirv.c b/libs/vkd3d-shader/spirv.c
index adb9f75f..f0154272 100644
--- a/libs/vkd3d-shader/spirv.c
+++ b/libs/vkd3d-shader/spirv.c
@@ -2241,6 +2241,7 @@ struct vkd3d_dxbc_compiler
     struct vkd3d_spirv_builder spirv_builder;
 
     uint32_t options;
+    uint32_t quirks;
 
     struct rb_tree symbol_table;
     uint32_t temp_id;
@@ -2350,6 +2351,21 @@ struct vkd3d_dxbc_compiler *vkd3d_dxbc_compiler_create(const struct vkd3d_shader
     compiler->shader_version = *shader_version;
     compiler->descriptor_qa_shader_hash = shader_hash;
 
+    if (compile_args && compile_args->quirks)
+    {
+        for (i = 0; i < compile_args->quirks->num_hashes; i++)
+        {
+            if (compile_args->quirks->hashes[i].shader_hash == shader_hash)
+            {
+                compiler->quirks = compile_args->quirks->hashes[i].quirks;
+                break;
+            }
+        }
+
+        if (i == compile_args->quirks->num_hashes)
+            compiler->quirks = compile_args->quirks->default_quirks;
+    }
+
     max_element_count = max(output_signature->element_count, patch_constant_signature->element_count);
     if (!(compiler->output_info = vkd3d_calloc(max_element_count, sizeof(*compiler->output_info))))
     {
@@ -9023,6 +9039,12 @@ static void vkd3d_dxbc_compiler_emit_lod(struct vkd3d_dxbc_compiler *compiler,
             dst, val_id, image.sampled_type, resource->swizzle);
 }
 
+static bool vkd3d_dxbc_compiler_has_quirk(struct vkd3d_dxbc_compiler *compiler,
+        enum vkd3d_shader_quirk quirk)
+{
+    return !!(compiler->quirks & quirk);
+}
+
 static void vkd3d_dxbc_compiler_emit_sample(struct vkd3d_dxbc_compiler *compiler,
         const struct vkd3d_shader_instruction *instruction)
 {