From c1a6dc93bfa5977de0ea256562058be4f1b73353 Mon Sep 17 00:00:00 2001
From: Wiseguy <68165316+Mr-Wiseguy@users.noreply.github.com>
Date: Sat, 19 Jul 2025 03:39:41 -0400
Subject: [PATCH] Implement fixed address and globally loaded sections in mods,
 respect section index in mod self-section relocs (#150)

---
 include/recompiler/context.h |  2 ++
 src/mod_symbols.cpp          | 19 ++++++++++++++++++-
 src/recompilation.cpp        | 10 ++++++++--
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/include/recompiler/context.h b/include/recompiler/context.h
index a3f0ac6..7b8c1f7 100644
--- a/include/recompiler/context.h
+++ b/include/recompiler/context.h
@@ -104,6 +104,8 @@ namespace N64Recomp {
         bool executable = false;
         bool relocatable = false; // TODO is this needed? relocs being non-empty should be an equivalent check.
         bool has_mips32_relocs = false;
+        bool fixed_address = false; // Only used in mods, indicates that the section shouldn't be relocated or placed into mod memory.
+        bool globally_loaded = false; // Only used in mods, indicates that the section's functions should be globally loaded. Does not actually load the section's contents into ram.
         std::optional<uint32_t> got_ram_addr = std::nullopt;
     };
 
diff --git a/src/mod_symbols.cpp b/src/mod_symbols.cpp
index ab80b04..c65b08e 100644
--- a/src/mod_symbols.cpp
+++ b/src/mod_symbols.cpp
@@ -20,6 +20,11 @@ struct FileSubHeaderV1 {
     uint32_t string_data_size;
 };
 
+enum class SectionFlags : uint32_t {
+    FixedAddress = 1 << 0,
+    GloballyLoaded = 1 << 1,
+};
+
 struct SectionHeaderV1 {
     uint32_t flags;
     uint32_t file_offset;
@@ -172,10 +177,22 @@ bool parse_v1(std::span<const char> data, const std::unordered_map<uint32_t, uin
         cur_section.bss_size = section_header->bss_size;
         cur_section.name = "mod_section_" + std::to_string(section_index);
         cur_section.relocatable = true;
+        cur_section.fixed_address = (section_header->flags & static_cast<uint32_t>(SectionFlags::FixedAddress)) != 0;
+        cur_section.globally_loaded = (section_header->flags & static_cast<uint32_t>(SectionFlags::GloballyLoaded)) != 0;
+
+        if (cur_section.fixed_address && !cur_section.globally_loaded) {
+            printf("Fixed address sections that aren't globally loaded aren't currently supported\n");
+            return false;
+        }
+
+        if (cur_section.globally_loaded && !cur_section.fixed_address) {
+            printf("A globally loaded section must have a fixed address\n");
+            return false;
+        }
+
         uint32_t num_funcs = section_header->num_funcs;
         uint32_t num_relocs = section_header->num_relocs;
 
-
         const FuncV1* funcs = reinterpret_data<FuncV1>(data, offset, num_funcs);
         if (funcs == nullptr) {
             printf("Failed to read funcs (count: %d)\n", num_funcs);
diff --git a/src/recompilation.cpp b/src/recompilation.cpp
index 5cfe8e5..a54b85f 100644
--- a/src/recompilation.cpp
+++ b/src/recompilation.cpp
@@ -152,6 +152,7 @@ bool process_instruction(GeneratorType& generator, const N64Recomp::Context& con
     }
 
     N64Recomp::RelocType reloc_type = N64Recomp::RelocType::R_MIPS_NONE;
+    bool has_reloc = false;
     uint32_t reloc_section = 0;
     uint32_t reloc_target_section_offset = 0;
     size_t reloc_reference_symbol = (size_t)-1;
@@ -162,6 +163,7 @@ bool process_instruction(GeneratorType& generator, const N64Recomp::Context& con
 
     // Check if this instruction has a reloc.
     if (section.relocs.size() > 0 && section.relocs[reloc_index].address == instr_vram) {
+        has_reloc = true;
         // Get the reloc data for this instruction
         const auto& reloc = section.relocs[reloc_index];
         reloc_section = reloc.target_section;
@@ -257,7 +259,7 @@ bool process_instruction(GeneratorType& generator, const N64Recomp::Context& con
         return true;
     };
 
-    auto print_func_call_by_address = [&generator, reloc_target_section_offset, reloc_section, reloc_reference_symbol, reloc_type, &context, &func, &static_funcs_out, &needs_link_branch, &print_indent, &process_delay_slot, &print_link_branch]
+    auto print_func_call_by_address = [&generator, reloc_target_section_offset, has_reloc, reloc_section, reloc_reference_symbol, reloc_type, &context, &func, &static_funcs_out, &needs_link_branch, &print_indent, &process_delay_slot, &print_link_branch]
         (uint32_t target_func_vram, bool tail_call = false, bool indent = false)
     {
         bool call_by_lookup = false;
@@ -294,7 +296,11 @@ bool process_instruction(GeneratorType& generator, const N64Recomp::Context& con
                 }
             }
             else {
-                JalResolutionResult jal_result = resolve_jal(context, func.section_index, target_func_vram, matched_func_index);
+                uint32_t target_section = func.section_index;
+                if (has_reloc) {
+                    target_section = reloc_section;
+                }
+                JalResolutionResult jal_result = resolve_jal(context, target_section, target_func_vram, matched_func_index);
 
                 switch (jal_result) {
                     case JalResolutionResult::NoMatch: