From 825f14dc90a1f9adb47c647bbdee4b312aa5309a Mon Sep 17 00:00:00 2001
From: Daan Vanden Bosch <daan.v.d.bosch@gmail.com>
Date: Tue, 1 Oct 2019 22:47:01 +0200
Subject: [PATCH] Fixed a disassembler bug: va list arg_push* instructions
 would not be output when in automatic stack management mode.

---
 .../scripting/disassembly.test.ts             | 37 ++++++++++++++++++-
 src/quest_editor/scripting/disassembly.ts     | 17 ++++++++-
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/src/quest_editor/scripting/disassembly.test.ts b/src/quest_editor/scripting/disassembly.test.ts
index b3ffc473..1ca42de4 100644
--- a/src/quest_editor/scripting/disassembly.test.ts
+++ b/src/quest_editor/scripting/disassembly.test.ts
@@ -6,7 +6,7 @@ import { BufferCursor } from "../../core/data_formats/cursor/BufferCursor";
 import { parse_bin, write_bin } from "../../core/data_formats/parsing/quest/bin";
 import { assemble } from "./assembly";
 import { disassemble } from "./disassembly";
-import { Instruction, object_code_equal, SegmentType } from "./instructions";
+import { Instruction, object_code_equal, Segment, SegmentType } from "./instructions";
 import { Opcode } from "./opcodes";
 
 test("vararg instructions should be disassembled correctly", () => {
@@ -36,6 +36,40 @@ test("vararg instructions should be disassembled correctly", () => {
     );
 });
 
+// arg_push* instructions should always be output when in a va list whether manual stack management
+// is on or off.
+test("va list instructions should be disassembled correctly", () => {
+    const ir: Segment[] = [
+        {
+            type: SegmentType.Instructions,
+            labels: [0],
+            instructions: [
+                new Instruction(Opcode.VA_START, []),
+                new Instruction(Opcode.ARG_PUSHW, [{ value: 1337, size: 2 }]),
+                new Instruction(Opcode.VA_CALL, [{ value: 100, size: 2 }]),
+                new Instruction(Opcode.VA_END, []),
+                new Instruction(Opcode.RET, []),
+            ],
+        },
+    ];
+
+    for (const manual_stack of [true, false]) {
+        const asm = disassemble(ir, manual_stack);
+
+        expect(asm).toEqual(
+            `.code
+
+0:
+    va_start
+    arg_pushw 1337
+    va_call 100
+    va_end
+    ret
+`.split("\n"),
+        );
+    }
+});
+
 // Round-trip test.
 test("assembling disassembled object code with manual stack management should result in the same IR", () => {
     const orig_buffer = readFileSync("test/resources/quest27_e.bin");
@@ -62,7 +96,6 @@ test("assembling disassembled object code with automatic stack management should
     expect(warnings).toEqual([]);
 
     expect(object_code_equal(object_code, bin.object_code)).toBe(true);
-    // expect(object_code).toBe(bin.object_code);
 });
 
 // Round-trip test.
diff --git a/src/quest_editor/scripting/disassembly.ts b/src/quest_editor/scripting/disassembly.ts
index a5375b8f..2a023e2d 100644
--- a/src/quest_editor/scripting/disassembly.ts
+++ b/src/quest_editor/scripting/disassembly.ts
@@ -1,6 +1,6 @@
 import { reinterpret_i32_as_f32 } from "../../core/primitive_conversion";
 import { Arg, Segment, SegmentType } from "./instructions";
-import { AnyType, Kind, Param, StackInteraction } from "./opcodes";
+import { AnyType, Kind, Opcode, Param, StackInteraction } from "./opcodes";
 import Logger from "js-logger";
 
 const logger = Logger.get("quest_editor/scripting/disassembly");
@@ -76,8 +76,21 @@ export function disassemble(object_code: Segment[], manual_stack = false): strin
         } else if (segment.type === SegmentType.String) {
             lines.push("    " + JSON.stringify(segment.value));
         } else {
+            // SegmentType.Instructions
+            let in_va_list = false;
+
             for (const instruction of segment.instructions) {
-                if (!manual_stack && instruction.opcode.stack === StackInteraction.Push) {
+                if (instruction.opcode.code === Opcode.VA_START.code) {
+                    in_va_list = true;
+                } else if (instruction.opcode.code === Opcode.VA_END.code) {
+                    in_va_list = false;
+                }
+
+                if (
+                    !manual_stack &&
+                    !in_va_list &&
+                    instruction.opcode.stack === StackInteraction.Push
+                ) {
                     stack.push(...add_type_to_args(instruction.opcode.params, instruction.args));
                 } else {
                     let args: string[] = [];