[decompiler] fix (gpr->fpr when an integer arg is converted to float (#482)

* fix gpr fpr bug

* remove unused variable

decompiler/IR2/Env.cpp

@@ -489,6 +489,12 @@ void Env::disable_def(const RegisterAccess& access, DecompWarnings& warnings) {
   }
 }
 
+void Env::disable_use(const RegisterAccess& access) {
+  if (has_local_vars()) {
+    m_var_names.disable_use(access);
+  }
+}
+
 /*!
  * Set the stack hints. This must be done before type analysis.
  * This actually parses the types, so it should be done after the dts is set up.

decompiler/IR2/Env.h

@@ -162,11 +162,7 @@ class Env {
   const std::vector<StackVarEntry>& stack_var_hints() const { return m_stack_vars; }
 
   const UseDefInfo& get_use_def_info(const RegisterAccess& ra) const;
-  void disable_use(const RegisterAccess& access) {
-    if (has_local_vars()) {
-      m_var_names.disable_use(access);
-    }
-  }
+  void disable_use(const RegisterAccess& access);
 
   void disable_def(const RegisterAccess& access, DecompWarnings& warnings);
 

decompiler/IR2/FormExpressionAnalysis.cpp

@@ -143,9 +143,14 @@ void pop_helper(const std::vector<RegisterAccess>& vars,
           submit_reg_to_var.push_back(var_idx);
           submit_regs.push_back(var.reg());
         } else {
-          //          fmt::print("Unsafe to pop {}: used {} times, def {} times, expected use {}\n",
-          //                     var.to_string(env), use_def.use_count(), use_def.def_count(),
-          //                     times);
+          /*auto var_id = env.get_program_var_id(var);
+          fmt::print(
+              "Unsafe to pop {}: used {} times, def {} times, expected use {} ({} {} rd: {}) ({}
+             {})\n", var.to_string(env), use_def.use_count(), use_def.def_count(), times,
+              var.reg().to_string(), var.idx(), var.mode() == AccessMode::READ,
+             var_id.reg.to_string(), var_id.id);
+              */
+
           //          if (var.to_string(env) == "a3-0") {
           //            for (auto& use : use_def.uses) {
           //              if (!use.disabled) {

decompiler/analysis/variable_naming.cpp

@@ -252,6 +252,11 @@ bool is_arg_reg(Register r) {
   }
 }
 
+int arg_reg_idx(Register r) {
+  assert(is_arg_reg(r));
+  return (int)r.get_gpr() - (int)Reg::A0;
+}
+
 bool is_saved_reg(Register r) {
   if (r.get_kind() == Reg::GPR) {
     if (r.get_gpr() == Reg::GP) {
@@ -349,8 +354,19 @@ SSA make_rc_ssa(const Function& function, const RegUsageInfo& rui, const Functio
 
             if (is_possible_coloring_move(dst, src) &&
                 rui.op.at(op_id).consumes.find(src) != rui.op.at(op_id).consumes.end()) {
-              ssa_i.is_arg_coloring_move = true;
-              got_not_arg_coloring = false;
+              // an integer argument going into a fpr for int->float conversion shouldn't
+              // be recognized as a coloring move.
+              if (function.type.arg_count() > 0) {
+                auto arg_idx = arg_reg_idx(src);
+                if (dst.get_kind() != Reg::FPR ||
+                    function.type.get_arg(arg_idx) == TypeSpec("float")) {
+                  ssa_i.is_arg_coloring_move = true;
+                  if (dst.get_kind() == Reg::FPR) {
+                    ssa_i.is_gpr_fpr_coloring_move = true;
+                  }
+                  got_not_arg_coloring = false;
+                }
+              }
             }
           }
         }
@@ -758,6 +774,7 @@ std::unordered_map<RegId, UseDefInfo, RegId::hash> SSA::get_use_def_info(
       if (instr.is_dead_set) {
         continue;
       }
+
       if (instr.dst.has_value()) {
         // get the SSA var:
         auto ssa_var_id =

decompiler/analysis/variable_naming.h

@@ -111,6 +111,7 @@ struct SSA {
     std::vector<VarSSA> src;
     int op_id = -1;
     bool is_arg_coloring_move = false;
+    bool is_gpr_fpr_coloring_move = false;
     bool is_dead_set = false;
 
     std::string print(const VarMapSSA& var_map) const;