vk_shader_compiler: Implement the decompiler in SPIR-V

src/video_core/shader/ast.h

@@ -205,13 +205,29 @@ public:
         return nullptr;
     }
 
-    void MarkLabelUnused() const {
+    void MarkLabelUnused() {
         auto inner = std::get_if<ASTLabel>(&data);
         if (inner) {
             inner->unused = true;
         }
     }
 
+    bool IsLabelUnused() const {
+        auto inner = std::get_if<ASTLabel>(&data);
+        if (inner) {
+            return inner->unused;
+        }
+        return true;
+    }
+
+    u32 GetLabelIndex() const {
+        auto inner = std::get_if<ASTLabel>(&data);
+        if (inner) {
+            return inner->index;
+        }
+        return -1;
+    }
+
     Expr GetIfCondition() const {
         auto inner = std::get_if<ASTIfThen>(&data);
         if (inner) {
@@ -336,6 +352,10 @@ public:
         return variables;
     }
 
+    const std::vector<ASTNode>& GetLabels() const {
+        return labels;
+    }
+
 private:
     bool IsBackwardsJump(ASTNode goto_node, ASTNode label_node) const;