coff: fix runtime traps

src/arch/x86_64/CodeGen.zig

@@ -4204,6 +4204,7 @@ fn airRet(self: *Self, inst: Air.Inst.Index) !void {
         },
         .stack_offset => {
             const reg = try self.copyToTmpRegister(Type.usize, self.ret_mcv);
+            log.warn("REG = {}", .{reg});
             const reg_lock = self.register_manager.lockRegAssumeUnused(reg);
             defer self.register_manager.unlockReg(reg_lock);
 
@@ -5854,7 +5855,11 @@ fn genInlineMemcpy(
     len: MCValue,
     opts: InlineMemcpyOpts,
 ) InnerError!void {
-    // TODO preserve contents of .rax and .rcx if not free, and then restore
+    // TODO: Preserve contents of .rax and .rcx if not free and locked, and then restore
+    // How can we do this without context if the value inside .rax or .rcx we preserve contains
+    // value needed to perform the memcpy in the first place?
+    // I think we should have an accumulator-based context that we pass with each subsequent helper
+    // call until we resolve the entire instruction.
     try self.register_manager.getReg(.rax, null);
     try self.register_manager.getReg(.rcx, null);
 

src/arch/x86_64/abi.zig

@@ -447,7 +447,7 @@ pub fn getCAbiIntReturnRegs(target: Target) []const Register {
 }
 
 const gp_regs = [_]Register{
-    .rax, .rbx, .rcx, .rdx, .rsi, .rdi, .r8, .r9, .r10, .r11, .r12, .r13, .r14, .r15,
+    .rbx, .r12, .r13, .r14, .r15, .rax, .rcx, .rdx, .rsi, .rdi, .r8, .r9, .r10, .r11,
 };
 const sse_avx_regs = [_]Register{
     .ymm0, .ymm1, .ymm2,  .ymm3,  .ymm4,  .ymm5,  .ymm6,  .ymm7,

src/link/Coff.zig

@@ -1053,7 +1053,7 @@ pub fn updateDecl(self: *Coff, module: *Module, decl_index: Module.Decl.Index) !
         .ty = decl.ty,
         .val = decl_val,
     }, &code_buffer, .none, .{
-        .parent_atom_index = 0,
+        .parent_atom_index = decl.link.coff.sym_index,
     });
     const code = switch (res) {
         .externally_managed => |x| x,