Subzero, MIPS32: Sandbox initial patch

src/IceTargetLoweringMIPS32.h

Index: src/IceTargetLoweringMIPS32.h
diff --git a/src/IceTargetLoweringMIPS32.h b/src/IceTargetLoweringMIPS32.h
index e7cc5a322a85cf43210141b892306e23c55b073a..2c8c96b657dadf1aaf678cc8bfdf829ab977efa1 100644
--- a/src/IceTargetLoweringMIPS32.h
+++ b/src/IceTargetLoweringMIPS32.h
@@ -580,6 +580,34 @@ public:
 
   void lowerArguments() override;
 
+  class Sandboxer {
+    Sandboxer() = delete;
+    Sandboxer(const Sandboxer &) = delete;
+    Sandboxer &operator=(const Sandboxer &) = delete;
+
+  public:
+    explicit Sandboxer(
+        TargetMIPS32 *Target,
+        InstBundleLock::Option BundleOption = InstBundleLock::Opt_None);
+    ~Sandboxer();
+
+    void addiu_sp(uint32_t StackOffset);
+    void lw(Variable *Dest, OperandMIPS32Mem *Mem);
+    void sw(Variable *Dest, OperandMIPS32Mem *Mem);
+    void ret(Variable *RetAddr, Variable *RetValue);
+    void reset_sp(Variable *Src);
+    InstMIPS32Call *jal(Variable *ReturnReg, Operand *CallTarget);
+
+  private:
+    TargetMIPS32 *const Target;
+    const InstBundleLock::Option BundleOption;
+    std::unique_ptr<AutoBundle> Bundler;
+
+    void createAutoBundle();
+  };
+
+  const bool NeedSandboxing;
+
   /// Make a pass through the SortedSpilledVariables and actually assign stack
   /// slots. SpillAreaPaddingBytes takes into account stack alignment padding.
   /// The SpillArea starts after that amount of padding. This matches the scheme