From a5eaea94cbc8b2c7c79ebff1b89b2e4d5c19ac2a Mon Sep 17 00:00:00 2001
From: angie <angheloalf95@gmail.com>
Date: Tue, 14 May 2024 16:22:00 -0400
Subject: [PATCH] Handle tail calls in the middle of functions

---
 .vscode/c_cpp_properties.json | 16 ++++++++++++++++
 src/main.cpp                  |  2 +-
 src/recompilation.cpp         | 27 ++++++++++++++++++++++-----
 3 files changed, 39 insertions(+), 6 deletions(-)
 create mode 100644 .vscode/c_cpp_properties.json

diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
new file mode 100644
index 0000000..2e8c75f
--- /dev/null
+++ b/.vscode/c_cpp_properties.json
@@ -0,0 +1,16 @@
+{
+    "configurations": [
+        {
+            "name": "Linux",
+            "includePath": [
+                "${workspaceFolder}/**"
+            ],
+            "defines": [],
+            "compilerPath": "/usr/bin/clang",
+            "intelliSenseMode": "linux-clang-x64",
+            "cStandard": "c17",
+            "cppStandard": "c++20",
+        }
+    ],
+    "version": 4
+}
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index 4cab9e1..88e11ae 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -503,7 +503,6 @@ std::unordered_set<std::string> ignored_funcs {
 
     // libgcc math routines (these throw off the recompiler)
     "__divdi3",
-    "__udivdi3",
     "__moddi3",
 
     // ido math routines
@@ -626,6 +625,7 @@ std::unordered_set<std::string> renamed_funcs{
     "flush_window",
 
     "__muldi3",
+    "__udivdi3",
     "__umoddi3",
     "div64_64",
     "div64_32",
diff --git a/src/recompilation.cpp b/src/recompilation.cpp
index 8c5bf4e..32c7ac7 100644
--- a/src/recompilation.cpp
+++ b/src/recompilation.cpp
@@ -124,7 +124,7 @@ bool process_instruction(const RecompPort::Context& context, const RecompPort::C
         fmt::print(output_file, ";\n    }}\n");
     };
 
-    auto print_func_call = [&](uint32_t target_func_vram) {
+    auto print_func_call = [&](uint32_t target_func_vram, bool link_branch = true) {
         const auto matching_funcs_find = context.functions_by_vram.find(target_func_vram);
         std::string jal_target_name;
         uint32_t section_vram_start = section.ram_addr;
@@ -190,7 +190,7 @@ bool process_instruction(const RecompPort::Context& context, const RecompPort::C
                 return false;
             }
         }
-        needs_link_branch = true;
+        needs_link_branch = link_branch;
         print_unconditional_branch("{}(rdram, ctx)", jal_target_name);
         return true;
     };
@@ -492,7 +492,7 @@ bool process_instruction(const RecompPort::Context& context, const RecompPort::C
     case InstrId::cpu_swr:
         print_line("do_swr(rdram, {}, {}{}, {}{})", signed_imm_string, ctx_gpr_prefix(base), base, ctx_gpr_prefix(rt), rt);
         break;
-        
+
     // Branches
     case InstrId::cpu_jal:
         print_func_call(instr.getBranchVramGeneric());
@@ -511,7 +511,7 @@ bool process_instruction(const RecompPort::Context& context, const RecompPort::C
         {
             uint32_t branch_target = instr.getBranchVramGeneric();
             if (branch_target == instr_vram) {
-                print_line("void pause_self(uint8_t *rdram); pause_self(rdram)");
+                print_line("pause_self(rdram)");
             }
             // Check if the branch is within this function
             else if (branch_target >= func.vram && branch_target < func_vram_end) {
@@ -522,6 +522,23 @@ bool process_instruction(const RecompPort::Context& context, const RecompPort::C
                 fmt::print("Tail call in {}\n", func.name);
                 print_func_call(branch_target);
             }
+            // This may be a tail call in the middle of the control flow due to a previous check
+            // For example:
+            // ```c
+            // void test() {
+            //     if (SOME_CONDITION) {
+            //         do_a();
+            //     } else {
+            //         do_b();
+            //     }
+            // }
+            // ```
+            // FIXME: how to deal with static functions?
+            else if (context.functions_by_vram.find(branch_target) != context.functions_by_vram.end()) {
+                fmt::print("Tail call in {}\n", func.name);
+                print_func_call(branch_target, false);
+                print_line("return");
+            }
             else {
                 fmt::print(stderr, "Unhandled branch in {} at 0x{:08X} to 0x{:08X}\n", func.name, instr_vram, branch_target);
                 return false;
@@ -536,7 +553,7 @@ bool process_instruction(const RecompPort::Context& context, const RecompPort::C
                 [instr_vram](const RecompPort::JumpTable& jtbl) {
                     return jtbl.jr_vram == instr_vram;
                 });
-            
+
             if (jtbl_find_result != stats.jump_tables.end()) {
                 const RecompPort::JumpTable& cur_jtbl = *jtbl_find_result;
                 bool dummy_needs_link_branch, dummy_is_branch_likely;