[PATCH vkd3d 6/7] vkd3d-shader/hlsl: Don't bother synthesizing a temp for input or output variables if they're not written to or read from, respectively.

[Zebediah Figura]

As a cheap substitute for actual variable copy-prop.

Signed-off-by: Zebediah Figura <zfigura at codeweavers.com>
---
 libs/vkd3d-shader/hlsl_codegen.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/libs/vkd3d-shader/hlsl_codegen.c b/libs/vkd3d-shader/hlsl_codegen.c
index df10ca272..495ba7c47 100644
--- a/libs/vkd3d-shader/hlsl_codegen.c
+++ b/libs/vkd3d-shader/hlsl_codegen.c
@@ -34,6 +34,13 @@ static void prepend_uniform_copy(struct hlsl_ctx *ctx, struct list *instrs, stru
     /* Use the synthetic name for the temp, rather than the uniform, so that we
      * can write the uniform name into the shader reflection data. */
 
+    if (!temp->first_write)
+    {
+        temp->is_uniform = 1;
+        list_add_tail(&ctx->extern_vars, &temp->extern_entry);
+        return;
+    }
+
     if (!(uniform = hlsl_new_var(ctx, temp->name, temp->data_type, temp->loc, NULL, 0, &temp->reg_reservation)))
         return;
     list_add_before(&temp->scope_entry, &uniform->scope_entry);
@@ -67,6 +74,14 @@ static void prepend_input_copy(struct hlsl_ctx *ctx, struct list *instrs, struct
     struct hlsl_ir_load *load;
     struct hlsl_ir_var *input;
 
+    /* We still need to split up non-vector types. */
+    if (!var->first_write && var->data_type->type <= HLSL_CLASS_VECTOR)
+    {
+        var->is_input_semantic = 1;
+        list_add_tail(&ctx->extern_vars, &var->extern_entry);
+        return;
+    }
+
     if (!(name = hlsl_get_string_buffer(ctx)))
         return;
     vkd3d_string_buffer_printf(name, "<input-%s%u>", semantic->name, semantic->index);
@@ -138,6 +153,14 @@ static void append_output_copy(struct hlsl_ctx *ctx, struct list *instrs, struct
     struct hlsl_ir_var *output;
     struct hlsl_ir_load *load;
 
+    /* We still need to split up non-vector types. */
+    if (!var->last_read && var->data_type->type <= HLSL_CLASS_VECTOR)
+    {
+        var->is_output_semantic = 1;
+        list_add_tail(&ctx->extern_vars, &var->extern_entry);
+        return;
+    }
+
     if (!(name = hlsl_get_string_buffer(ctx)))
         return;
     vkd3d_string_buffer_printf(name, "<output-%s%u>", semantic->name, semantic->index);
@@ -1306,6 +1329,12 @@ int hlsl_emit_dxbc(struct hlsl_ctx *ctx, struct hlsl_ir_function_decl *entry_fun
 
     list_move_head(&body->instrs, &ctx->static_initializers);
 
+    /* Do an initial liveness pass for externs so that we don't create
+     * unnecessary temps. Note that we might modify the instruction stream
+     * during the pass, but we're only checking whether a variable was read to
+     * or written from at all, so it's okay. */
+    compute_liveness(ctx, entry_func);
+
     LIST_FOR_EACH_ENTRY(var, &ctx->globals->vars, struct hlsl_ir_var, scope_entry)
     {
         if (var->modifiers & HLSL_STORAGE_UNIFORM)
-- 
2.33.0