rewriter: clean up memory managment.

It deleted the passed ICSlotRewrite* and there was no way for a caller to know this without looking at the source.
Make the ownership explicit by using a std::unique_ptr

src/asm_writing/icinfo.cpp

@@ -151,8 +151,8 @@ assembler::GenericRegister ICSlotRewrite::returnRegister() {
 
 
 
-ICSlotRewrite* ICInfo::startRewrite(const char* debug_name) {
-    return new ICSlotRewrite(this, debug_name);
+std::unique_ptr<ICSlotRewrite> ICInfo::startRewrite(const char* debug_name) {
+    return std::unique_ptr<ICSlotRewrite>(new ICSlotRewrite(this, debug_name));
 }
 
 ICSlotInfo* ICInfo::pickEntryForRewrite(const char* debug_name) {
@@ -236,11 +236,11 @@ std::unique_ptr<ICInfo> registerCompiledPatchpoint(uint8_t* start_addr, uint8_t*
         // writer->emitNop();
         // writer->emitGuardFalse();
 
-        std::unique_ptr<Assembler> writer(new Assembler(start, ic->slot_size));
-        writer->nop();
-        // writer->trap();
-        // writer->jmp(JumpDestination::fromStart(ic->slot_size * (ic->num_slots - i)));
-        writer->jmp(JumpDestination::fromStart(slowpath_start_addr - start));
+        Assembler writer(start, ic->slot_size);
+        writer.nop();
+        // writer.trap();
+        // writer.jmp(JumpDestination::fromStart(ic->slot_size * (ic->num_slots - i)));
+        writer.jmp(JumpDestination::fromStart(slowpath_start_addr - start));
     }
 
     ICInfo* icinfo = new ICInfo(start_addr, slowpath_rtn_addr, continue_addr, stack_info, ic->num_slots, ic->slot_size,
@@ -272,10 +272,10 @@ void ICInfo::clear(ICSlotInfo* icentry) {
     if (VERBOSITY() >= 4)
         printf("clearing patchpoint %p, slot at %p\n", start_addr, start);
 
-    std::unique_ptr<Assembler> writer(new Assembler(start, getSlotSize()));
-    writer->nop();
-    writer->jmp(JumpDestination::fromStart(getSlotSize()));
-    assert(writer->bytesWritten() <= IC_INVALDITION_HEADER_SIZE);
+    Assembler writer(start, getSlotSize());
+    writer.nop();
+    writer.jmp(JumpDestination::fromStart(getSlotSize()));
+    assert(writer.bytesWritten() <= IC_INVALDITION_HEADER_SIZE);
 
     // std::unique_ptr<MCWriter> writer(createMCWriter(start, getSlotSize(), 0));
     // writer->emitNop();

src/asm_writing/icinfo.h

@@ -119,7 +119,7 @@ public:
     llvm::CallingConv::ID getCallingConvention() { return calling_conv; }
     const std::vector<int>& getLiveOuts() { return live_outs; }
 
-    ICSlotRewrite* startRewrite(const char* debug_name);
+    std::unique_ptr<ICSlotRewrite> startRewrite(const char* debug_name);
     void clear(ICSlotInfo* entry);
 
     bool shouldAttempt();

src/asm_writing/rewriter.cpp

@@ -1676,11 +1676,11 @@ TypeRecorder* Rewriter::getTypeRecorder() {
     return rewrite->getTypeRecorder();
 }
 
-Rewriter::Rewriter(ICSlotRewrite* rewrite, int num_args, const std::vector<int>& live_outs)
-    : rewrite(rewrite),
-      assembler(rewrite->getAssembler()),
+Rewriter::Rewriter(std::unique_ptr<ICSlotRewrite> rewrite, int num_args, const std::vector<int>& live_outs)
+    : rewrite(std::move(rewrite)),
+      assembler(this->rewrite->getAssembler()),
       const_loader(this),
-      return_location(rewrite->returnRegister()),
+      return_location(this->rewrite->returnRegister()),
       failed(false),
       added_changing_action(false),
       marked_inside_ic(false),

src/asm_writing/rewriter.h

@@ -344,7 +344,7 @@ protected:
     std::vector<RewriterVar*> args;
     std::vector<RewriterVar*> live_outs;
 
-    Rewriter(ICSlotRewrite* rewrite, int num_args, const std::vector<int>& live_outs);
+    Rewriter(std::unique_ptr<ICSlotRewrite> rewrite, int num_args, const std::vector<int>& live_outs);
 
     std::vector<RewriterAction> actions;
     void addAction(const std::function<void()>& action, std::vector<RewriterVar*> const& vars, ActionType type) {