only lookup __[set/get/del]slice__ for slice AST nodes

before this change
C()[slice(1,2)] = "a"
would call into `__setslice__` because it got handled as
C()[1,2] = "a"

This commits adds cpythons assign_slice/apply_slice and add rewriter support for them.

src/asm_writing/rewriter.cpp

@@ -287,24 +287,29 @@ void RewriterVar::addGuard(uint64_t val) {
     rewriter->addAction([=]() { rewriter->_addGuard(this, val_var); }, { this, val_var }, ActionType::GUARD);
 }
 
-void Rewriter::_nextSlotJump(bool condition_eq) {
+void Rewriter::_nextSlotJump(assembler::ConditionCode condition) {
     // If a jump offset is larger then 0x80 the instruction encoding requires 6bytes instead of 2bytes.
     // This adds up quickly, thats why we will try to find another jump to the slowpath with the same condition with a
     // smaller offset and jump to it / use it as a trampoline.
     // The benchmark show that this increases the performance slightly even though it introduces additional jumps.
-    int& last_jmp_offset = condition_eq ? offset_eq_jmp_next_slot : offset_ne_jmp_next_slot;
-    auto condition = condition_eq ? assembler::COND_EQUAL : assembler::COND_NOT_EQUAL;
+    int last_jmp_offset = -1;
+    for (auto it = next_slot_jmps.rbegin(), it_end = next_slot_jmps.rend(); it != it_end; ++it) {
+        if (std::get<2>(*it) == condition) {
+            last_jmp_offset = std::get<0>(*it);
+            break;
+        }
+    }
 
     if (last_jmp_offset != -1 && assembler->bytesWritten() - last_jmp_offset < 0x80) {
         assembler->jmp_cond(assembler::JumpDestination::fromStart(last_jmp_offset), condition);
     } else {
-        last_jmp_offset = assembler->bytesWritten();
+        int last_jmp_offset = assembler->bytesWritten();
         assembler->jmp_cond(assembler::JumpDestination::fromStart(rewrite->getSlotSize()), condition);
         next_slot_jmps.emplace_back(last_jmp_offset, assembler->bytesWritten(), condition);
     }
 }
 
-void Rewriter::_addGuard(RewriterVar* var, RewriterVar* val_constant) {
+void Rewriter::_addGuard(RewriterVar* var, RewriterVar* val_constant, bool negate) {
     if (LOG_IC_ASSEMBLY)
         assembler->comment("_addGuard");
 
@@ -316,12 +321,15 @@ void Rewriter::_addGuard(RewriterVar* var, RewriterVar* val_constant) {
         assembler::Register reg = val_constant->getInReg(Location::any(), true, /* otherThan */ var_reg);
         assembler->cmp(var_reg, reg);
     } else {
+        if (val == 0)
+            assembler->test(var_reg, var_reg);
+        else
             assembler->cmp(var_reg, assembler::Immediate(val));
     }
 
     restoreArgs(); // can only do movs, doesn't affect flags, so it's safe
     assertArgsInPlace();
-    _nextSlotJump(false /*= not equal jmp */);
+    _nextSlotJump(negate ? assembler::COND_EQUAL : assembler::COND_NOT_EQUAL);
 
     var->bumpUse();
     val_constant->bumpUse();
@@ -333,32 +341,24 @@ void RewriterVar::addGuardNotEq(uint64_t val) {
     STAT_TIMER(t0, "us_timer_rewriter", 10);
 
     RewriterVar* val_var = rewriter->loadConst(val);
-    rewriter->addAction([=]() { rewriter->_addGuardNotEq(this, val_var); }, { this, val_var }, ActionType::GUARD);
+    rewriter->addAction([=]() { rewriter->_addGuard(this, val_var, true /* negate */); }, { this, val_var },
+                        ActionType::GUARD);
 }
 
-void Rewriter::_addGuardNotEq(RewriterVar* var, RewriterVar* val_constant) {
-    if (LOG_IC_ASSEMBLY)
-        assembler->comment("_addGuardNotEq");
+void RewriterVar::addGuardNotLt0() {
+    rewriter->addAction([=]() {
+        assembler::Register var_reg = this->getInReg();
+        rewriter->assembler->test(var_reg, var_reg);
 
-    assert(val_constant->is_constant);
-    uint64_t val = val_constant->constant_value;
+        rewriter->restoreArgs(); // can only do movs, doesn't affect flags, so it's safe
+        rewriter->assertArgsInPlace();
 
-    assembler::Register var_reg = var->getInReg();
-    if (isLargeConstant(val)) {
-        assembler::Register reg = val_constant->getInReg(Location::any(), true, /* otherThan */ var_reg);
-        assembler->cmp(var_reg, reg);
-    } else {
-        assembler->cmp(var_reg, assembler::Immediate(val));
-    }
+        rewriter->_nextSlotJump(assembler::COND_SIGN);
 
-    restoreArgs(); // can only do movs, doesn't affect flags, so it's safe
-    assertArgsInPlace();
-    _nextSlotJump(true /*= equal jmp */);
+        bumpUse();
+        rewriter->assertConsistent();
 
-    var->bumpUse();
-    val_constant->bumpUse();
-
-    assertConsistent();
+    }, { this }, ActionType::GUARD);
 }
 
 void RewriterVar::addAttrGuard(int offset, uint64_t val, bool negate) {
@@ -405,7 +405,7 @@ void Rewriter::_addAttrGuard(RewriterVar* var, int offset, RewriterVar* val_cons
 
     restoreArgs(); // can only do movs, doesn't affect flags, so it's safe
     assertArgsInPlace();
-    _nextSlotJump(negate);
+    _nextSlotJump(negate ? assembler::COND_EQUAL : assembler::COND_NOT_EQUAL);
 
     var->bumpUse();
     val_constant->bumpUse();
@@ -2220,8 +2220,6 @@ Rewriter::Rewriter(std::unique_ptr<ICSlotRewrite> rewrite, int num_args, const L
       marked_inside_ic(false),
       done_guarding(false),
       last_guard_action(-1),
-      offset_eq_jmp_next_slot(-1),
-      offset_ne_jmp_next_slot(-1),
       allocatable_regs(std_allocatable_regs) {
     initPhaseCollecting();
 

src/asm_writing/rewriter.h

@@ -147,6 +147,7 @@ public:
 
     void addGuard(uint64_t val);
     void addGuardNotEq(uint64_t val);
+    void addGuardNotLt0();
     void addAttrGuard(int offset, uint64_t val, bool negate = false);
     RewriterVar* getAttr(int offset, Location loc = Location::any(), assembler::MovType type = assembler::MovType::Q);
     // getAttrFloat casts to double (maybe I should make that separate?)
@@ -502,8 +503,6 @@ protected:
     }
 
     int last_guard_action;
-    int offset_eq_jmp_next_slot;
-    int offset_ne_jmp_next_slot;
 
     // keeps track of all jumps to the next slot so we can patch them if the size of the current slot changes
     std::vector<NextSlotJumpInfo> next_slot_jmps;
@@ -540,7 +539,7 @@ protected:
 
     bool finishAssembly(int continue_offset, bool& should_fill_with_nops, bool& variable_size_slots) override;
 
-    void _nextSlotJump(bool condition_eq);
+    void _nextSlotJump(assembler::ConditionCode condition);
     void _trap();
     void _loadConst(RewriterVar* result, int64_t val);
     void _setupCall(bool has_side_effects, llvm::ArrayRef<RewriterVar*> args = {},
@@ -557,8 +556,7 @@ protected:
     void _checkAndThrowCAPIException(RewriterVar* r, int64_t exc_val, assembler::MovType size);
 
     // The public versions of these are in RewriterVar
-    void _addGuard(RewriterVar* var, RewriterVar* val_constant);
-    void _addGuardNotEq(RewriterVar* var, RewriterVar* val_constant);
+    void _addGuard(RewriterVar* var, RewriterVar* val_constant, bool negate = false);
     void _addAttrGuard(RewriterVar* var, int offset, RewriterVar* val_constant, bool negate = false);
     void _getAttr(RewriterVar* result, RewriterVar* var, int offset, Location loc = Location::any(),
                   assembler::MovType type = assembler::MovType::Q);

src/capi/typeobject.cpp

@@ -1242,7 +1242,7 @@ static int slot_tp_descr_set(PyObject* self, PyObject* target, PyObject* value)
 
 PyObject* slot_sq_item(PyObject* self, Py_ssize_t i) noexcept {
     STAT_TIMER(t0, "us_timer_slot_sqitem", SLOT_AVOIDABILITY(self));
-    return getitemInternal<CAPI>(self, autoDecref(boxInt(i)));
+    return PyObject_GetItem(self, autoDecref(boxInt(i)));
 }
 
 /* Pyston change: static */ Py_ssize_t slot_sq_length(PyObject* self) noexcept {

src/codegen/ast_interpreter.cpp

@@ -554,12 +554,27 @@ void ASTInterpreter::doStore(AST_expr* node, STOLEN(Value) value) {
         Value target = visit_expr(subscript->value);
         AUTO_DECREF(target.o);
 
+        bool is_slice = (subscript->slice->type == AST_TYPE::Slice) && (((AST_Slice*)subscript->slice)->step == NULL);
+        if (is_slice) {
+            AST_Slice* slice = (AST_Slice*)subscript->slice;
+            Value lower = slice->lower ? visit_expr(slice->lower) : Value();
+            AUTO_XDECREF(lower.o);
+            Value upper = slice->upper ? visit_expr(slice->upper) : Value();
+            AUTO_XDECREF(upper.o);
+            assert(slice->step == NULL);
+
+            if (jit)
+                jit->emitAssignSlice(target, lower, upper, value);
+            assignSlice(target.o, lower.o, upper.o, value.o);
+        } else {
             Value slice = visit_slice(subscript->slice);
+
             AUTO_DECREF(slice.o);
 
             if (jit)
                 jit->emitSetItem(target, slice, value);
             setitem(target.o, slice.o, value.o);
+        }
     } else {
         RELEASE_ASSERT(0, "not implemented");
     }
@@ -1321,11 +1336,26 @@ Value ASTInterpreter::visit_delete(AST_Delete* node) {
                 AST_Subscript* sub = (AST_Subscript*)target_;
                 Value value = visit_expr(sub->value);
                 AUTO_DECREF(value.o);
+
+                bool is_slice = (sub->slice->type == AST_TYPE::Slice) && (((AST_Slice*)sub->slice)->step == NULL);
+                if (is_slice) {
+                    AST_Slice* slice = (AST_Slice*)sub->slice;
+                    Value lower = slice->lower ? visit_expr(slice->lower) : Value();
+                    AUTO_XDECREF(lower.o);
+                    Value upper = slice->upper ? visit_expr(slice->upper) : Value();
+                    AUTO_XDECREF(upper.o);
+                    assert(slice->step == NULL);
+
+                    if (jit)
+                        jit->emitAssignSlice(value, lower, upper, jit->imm(0ul));
+                    assignSlice(value.o, lower.o, upper.o, NULL);
+                } else {
                     Value slice = visit_slice(sub->slice);
                     AUTO_DECREF(slice.o);
                     if (jit)
                         jit->emitDelItem(value, slice);
                     delitem(value.o, slice.o);
+                }
                 break;
             }
             case AST_TYPE::Attribute: {
@@ -1735,10 +1765,31 @@ Value ASTInterpreter::visit_name(AST_Name* node) {
 Value ASTInterpreter::visit_subscript(AST_Subscript* node) {
     Value value = visit_expr(node->value);
     AUTO_DECREF(value.o);
+
+    bool is_slice = (node->slice->type == AST_TYPE::Slice) && (((AST_Slice*)node->slice)->step == NULL);
+    if (is_slice) {
+        AST_Slice* slice = (AST_Slice*)node->slice;
+        Value lower = slice->lower ? visit_expr(slice->lower) : Value();
+        AUTO_XDECREF(lower.o);
+        Value upper = slice->upper ? visit_expr(slice->upper) : Value();
+        AUTO_XDECREF(upper.o);
+        assert(slice->step == NULL);
+
+        Value v;
+        if (jit)
+            v.var = jit->emitApplySlice(value, lower, upper);
+        v.o = applySlice(value.o, lower.o, upper.o);
+        return v;
+    } else {
         Value slice = visit_slice(node->slice);
         AUTO_DECREF(slice.o);
 
-    return Value(getitem(value.o, slice.o), jit ? jit->emitGetItem(node, value, slice) : NULL);
+        Value v;
+        if (jit)
+            v.var = jit->emitGetItem(node, value, slice);
+        v.o = getitem(value.o, slice.o);
+        return v;
+    }
 }
 
 Value ASTInterpreter::visit_list(AST_List* node) {

src/codegen/baseline_jit.cpp

@@ -208,6 +208,14 @@ RewriterVar* JitFragmentWriter::emitAugbinop(AST_expr* node, RewriterVar* lhs, R
     return emitPPCall((void*)augbinop, { lhs, rhs, imm(op_type) }, 2 * 320, node).first->setType(RefType::OWNED);
 }
 
+RewriterVar* JitFragmentWriter::emitApplySlice(RewriterVar* target, RewriterVar* lower, RewriterVar* upper) {
+    if (!lower)
+        lower = imm(0ul);
+    if (!upper)
+        upper = imm(0ul);
+    return emitPPCall((void*)applySlice, { target, lower, upper }, 256).first->setType(RefType::OWNED);
+}
+
 RewriterVar* JitFragmentWriter::emitBinop(AST_expr* node, RewriterVar* lhs, RewriterVar* rhs, int op_type) {
     return emitPPCall((void*)binop, { lhs, rhs, imm(op_type) }, 2 * 240, node).first->setType(RefType::OWNED);
 }
@@ -553,6 +561,15 @@ RewriterVar* JitFragmentWriter::emitYield(RewriterVar* v) {
     return rtn;
 }
 
+void JitFragmentWriter::emitAssignSlice(RewriterVar* target, RewriterVar* lower, RewriterVar* upper,
+                                        RewriterVar* value) {
+    if (!lower)
+        lower = imm(0ul);
+    if (!upper)
+        upper = imm(0ul);
+    emitPPCall((void*)assignSlice, { target, lower, upper, value }, 256).first;
+}
+
 void JitFragmentWriter::emitDelAttr(RewriterVar* target, BoxedString* attr) {
     emitPPCall((void*)delattr, { target, imm(attr) }, 144).first;
 }

src/codegen/baseline_jit.h

@@ -239,6 +239,7 @@ public:
     RewriterVar* imm(void* val);
 
     RewriterVar* emitAugbinop(AST_expr* node, RewriterVar* lhs, RewriterVar* rhs, int op_type);
+    RewriterVar* emitApplySlice(RewriterVar* target, RewriterVar* lower, RewriterVar* upper);
     RewriterVar* emitBinop(AST_expr* node, RewriterVar* lhs, RewriterVar* rhs, int op_type);
     RewriterVar* emitCallattr(AST_expr* node, RewriterVar* obj, BoxedString* attr, CallattrFlags flags,
                               const llvm::ArrayRef<RewriterVar*> args, std::vector<BoxedString*>* keyword_names);
@@ -275,6 +276,7 @@ public:
     std::vector<RewriterVar*> emitUnpackIntoArray(RewriterVar* v, uint64_t num);
     RewriterVar* emitYield(RewriterVar* v);
 
+    void emitAssignSlice(RewriterVar* target, RewriterVar* lower, RewriterVar* upper, RewriterVar* value);
     void emitDelAttr(RewriterVar* target, BoxedString* attr);
     void emitDelGlobal(BoxedString* name);
     void emitDelItem(RewriterVar* target, RewriterVar* slice);

src/codegen/compvars.cpp

@@ -331,6 +331,9 @@ public:
 
     CompilerVariable* getitem(IREmitter& emitter, const OpInfo& info, ConcreteCompilerVariable* var,
                               CompilerVariable* slice) override {
+        ExceptionStyle target_exception_style = info.preferredExceptionStyle();
+        bool do_patchpoint = ENABLE_ICGETITEMS;
+
         if (slice->getType() == UNBOXED_SLICE) {
             UnboxedSlice slice_val = extractSlice(slice);
 
@@ -340,31 +343,37 @@ public:
                     = var->getType()->getattrType(attr, true)->callType(ArgPassSpec(1), { SLICE }, NULL);
                 assert(return_type->getConcreteType() == return_type);
 
-                if (return_type != UNDEF) {
                 llvm::Value* cstart, *cstop;
                 cstart = slice_val.start ? slice_val.start->makeConverted(emitter, UNKNOWN)->getValue()
                                          : emitter.setType(getNullPtr(g.llvm_value_type_ptr), RefType::BORROWED);
                 cstop = slice_val.stop ? slice_val.stop->makeConverted(emitter, UNKNOWN)->getValue()
                                        : emitter.setType(getNullPtr(g.llvm_value_type_ptr), RefType::BORROWED);
-
-                    llvm::Value* r = emitter.createCall3(info.unw_info, g.funcs.apply_slice, var->getValue(), cstart,
-                                                         cstop, CAPI, getNullPtr(g.llvm_value_type_ptr));
+                llvm::Value* r = NULL;
+                if (do_patchpoint) {
+                    ICSetupInfo* pp = createGetitemIC(info.getTypeRecorder(), info.getBJitICInfo());
+                    llvm::Instruction* uncasted = emitter.createIC(
+                        pp, (void*)(target_exception_style == CAPI ? pyston::apply_slice : pyston::applySlice),
+                        { var->getValue(), cstart, cstop }, info.unw_info, target_exception_style,
+                        getNullPtr(g.llvm_value_type_ptr));
+                    r = createAfter<llvm::IntToPtrInst>(uncasted, uncasted, g.llvm_value_type_ptr, "");
+                } else {
+                    r = emitter.createCall3(
+                        info.unw_info, target_exception_style == CAPI ? g.funcs.apply_slice : g.funcs.applySlice,
+                        var->getValue(), cstart, cstop, target_exception_style, getNullPtr(g.llvm_value_type_ptr));
+                }
                 emitter.setType(r, RefType::OWNED);
+                if (target_exception_style == CAPI)
                     emitter.setNullable(r, true);
 
+                if (return_type != UNDEF)
                     return new ConcreteCompilerVariable(static_cast<ConcreteCompilerType*>(return_type), r);
-                } else {
-                    // TODO: we could directly emit an exception if we know getitem is undefined but for now let it just
-                    // call the normal getitem which will raise the exception
-                }
+                return new ConcreteCompilerVariable(UNKNOWN, r);
             }
         }
 
         ConcreteCompilerVariable* converted_slice = slice->makeConverted(emitter, slice->getBoxType());
 
-        ExceptionStyle target_exception_style = info.preferredExceptionStyle();
 
-        bool do_patchpoint = ENABLE_ICGETITEMS;
         llvm::Value* rtn;
         if (do_patchpoint) {
             ICSetupInfo* pp = createGetitemIC(info.getTypeRecorder(), info.getBJitICInfo());

src/codegen/irgen/irgenerator.cpp

@@ -1508,7 +1508,6 @@ private:
     CompilerVariable* evalSubscript(AST_Subscript* node, const UnwindInfo& unw_info) {
         CompilerVariable* value = evalExpr(node->value, unw_info);
         CompilerVariable* slice = evalSlice(node->slice, unw_info);
-
         CompilerVariable* rtn = value->getitem(emitter, getOpInfoForNode(node, unw_info), slice);
         return rtn;
     }
@@ -1992,15 +1991,42 @@ private:
         t->setattr(emitter, getEmptyOpInfo(unw_info), target->attr.getBox(), val);
     }
 
+    void _assignSlice(llvm::Value* target, llvm::Value* value, const UnboxedSlice& slice_val,
+                      const UnwindInfo& unw_info) {
+        llvm::Value* cstart, *cstop;
+        cstart = slice_val.start ? slice_val.start->makeConverted(emitter, UNKNOWN)->getValue()
+                                 : emitter.setType(getNullPtr(g.llvm_value_type_ptr), RefType::BORROWED);
+        cstop = slice_val.stop ? slice_val.stop->makeConverted(emitter, UNKNOWN)->getValue()
+                               : emitter.setType(getNullPtr(g.llvm_value_type_ptr), RefType::BORROWED);
+
+        bool do_patchpoint = ENABLE_ICSETITEMS;
+        if (do_patchpoint) {
+            ICSetupInfo* pp = createSetitemIC(getEmptyOpInfo(unw_info).getTypeRecorder());
+
+            std::vector<llvm::Value*> llvm_args;
+            llvm_args.push_back(target);
+            llvm_args.push_back(cstart);
+            llvm_args.push_back(cstop);
+            llvm_args.push_back(value);
+
+            emitter.createIC(pp, (void*)pyston::assignSlice, llvm_args, unw_info);
+        } else {
+            emitter.createCall(unw_info, g.funcs.assignSlice, { target, cstart, cstop, value });
+        }
+    }
+
     void _doSetitem(AST_Subscript* target, CompilerVariable* val, const UnwindInfo& unw_info) {
         CompilerVariable* tget = evalExpr(target->value, unw_info);
-        CompilerVariable* slice = evalSlice(target->slice, unw_info);
 
+        CompilerVariable* slice = evalSlice(target->slice, unw_info);
         ConcreteCompilerVariable* converted_target = tget->makeConverted(emitter, tget->getBoxType());
-        ConcreteCompilerVariable* converted_slice = slice->makeConverted(emitter, slice->getBoxType());
-
         ConcreteCompilerVariable* converted_val = val->makeConverted(emitter, val->getBoxType());
 
+        if (slice->getType() == UNBOXED_SLICE && !extractSlice(slice).step) {
+            _assignSlice(converted_target->getValue(), converted_val->getValue(), extractSlice(slice), unw_info);
+        } else {
+            ConcreteCompilerVariable* converted_slice = slice->makeConverted(emitter, slice->getBoxType());
+
             // TODO add a CompilerVariable::setattr, which can (similar to getitem)
             // statically-resolve the function if possible, and only fall back to
             // patchpoints if it couldn't.
@@ -2015,8 +2041,9 @@ private:
 
                 emitter.createIC(pp, (void*)pyston::setitem, llvm_args, unw_info);
             } else {
-            emitter.createCall3(unw_info, g.funcs.setitem, converted_target->getValue(), converted_slice->getValue(),
-                                converted_val->getValue());
+                emitter.createCall3(unw_info, g.funcs.setitem, converted_target->getValue(),
+                                    converted_slice->getValue(), converted_val->getValue());
+            }
         }
     }
 
@@ -2125,6 +2152,12 @@ private:
         CompilerVariable* slice = evalSlice(target->slice, unw_info);
 
         ConcreteCompilerVariable* converted_target = tget->makeConverted(emitter, tget->getBoxType());
+
+        if (slice->getType() == UNBOXED_SLICE && !extractSlice(slice).step) {
+            _assignSlice(converted_target->getValue(),
+                         emitter.setType(getNullPtr(g.llvm_value_type_ptr), RefType::BORROWED), extractSlice(slice),
+                         unw_info);
+        } else {
             ConcreteCompilerVariable* converted_slice = slice->makeConverted(emitter, slice->getBoxType());
 
             bool do_patchpoint = ENABLE_ICDELITEMS;
@@ -2137,7 +2170,9 @@ private:
 
                 emitter.createIC(pp, (void*)pyston::delitem, llvm_args, unw_info);
             } else {
-            emitter.createCall2(unw_info, g.funcs.delitem, converted_target->getValue(), converted_slice->getValue());
+                emitter.createCall2(unw_info, g.funcs.delitem, converted_target->getValue(),
+                                    converted_slice->getValue());
+            }
         }
     }
 

src/codegen/runtime_hooks.cpp

@@ -229,6 +229,8 @@ void initGlobalFuncs(GlobalState& g) {
     GET(getiterHelper);
     GET(hasnext);
     GET(apply_slice);
+    GET(applySlice);
+    GET(assignSlice);
 
     GET(unpackIntoArray);
     GET(raiseAttributeError);

src/codegen/runtime_hooks.h

@@ -39,7 +39,7 @@ struct GlobalFuncs {
     llvm::Value* getattr, *getattr_capi, *setattr, *delattr, *delitem, *delGlobal, *nonzero, *binop, *compare,
         *augbinop, *unboxedLen, *getitem, *getitem_capi, *getclsattr, *getGlobal, *setitem, *unaryop, *import,
         *importFrom, *importStar, *repr, *exceptionMatches, *yield_capi, *getiterHelper, *hasnext, *setGlobal,
-        *apply_slice;
+        *apply_slice, *applySlice, *assignSlice;
 
     llvm::Value* unpackIntoArray, *raiseAttributeError, *raiseAttributeErrorStr, *raiseAttributeErrorCapi,
         *raiseAttributeErrorStrCapi, *raiseNotIterableError, *raiseIndexErrorStr, *raiseIndexErrorStrCapi,

src/runtime/classobj.cpp

@@ -777,6 +777,15 @@ Box* instanceGetslice(Box* _inst, Box* i, Box* j) {
     return runtimeCall(getslice_func, ArgPassSpec(2), i, j, NULL, NULL, NULL);
 }
 
+Box* instance_slice(PyObject* self, Py_ssize_t i, Py_ssize_t j) noexcept {
+    try {
+        return instanceGetslice(self, autoDecref(boxInt(i)), autoDecref((boxInt(j))));
+    } catch (ExcInfo e) {
+        setCAPIException(e);
+        return 0;
+    }
+}
+
 Box* instanceSetslice(Box* _inst, Box* i, Box* j, Box** sequence) {
     RELEASE_ASSERT(_inst->cls == instance_cls, "");
     BoxedInstance* inst = static_cast<BoxedInstance*>(_inst);
@@ -2005,5 +2014,6 @@ void setupClassobj() {
     instance_cls->tp_as_number->nb_index = instance_index;
     instance_cls->tp_as_number->nb_power = instance_pow;
     instance_cls->tp_as_number->nb_inplace_power = instance_ipow;
+    instance_cls->tp_as_sequence->sq_slice = instance_slice;
 }
 }

src/runtime/dict.cpp

@@ -377,13 +377,13 @@ extern "C" BORROWED(PyObject*) PyDict_GetItem(PyObject* dict, PyObject* key) noe
         /* preserve the existing exception */
         PyObject* err_type, *err_value, *err_tb;
         PyErr_Fetch(&err_type, &err_value, &err_tb);
-        Box* b = getitemInternal<CAPI>(dict, key);
+        Box* b = PyObject_GetItem(dict, key);
         /* ignore errors */
         PyErr_Restore(err_type, err_value, err_tb);
         Py_XDECREF(b);
         return b;
     } else {
-        Box* b = getitemInternal<CAPI>(dict, key);
+        Box* b = PyObject_GetItem(dict, key);
         if (b == NULL)
             PyErr_Clear();
         else
@@ -514,13 +514,7 @@ extern "C" int PyDict_DelItem(PyObject* op, PyObject* key) noexcept {
     }
 
     ASSERT(op->cls == attrwrapper_cls, "%s", getTypeName(op));
-    try {
-        delitem(op, key);
-        return 0;
-    } catch (ExcInfo e) {
-        setCAPIException(e);
-        return -1;
-    }
+    return PyObject_DelItem(op, key);
 }
 
 extern "C" int PyDict_DelItemString(PyObject* v, const char* key) noexcept {

src/runtime/inline/link_forcer.cpp

@@ -105,6 +105,8 @@ void force() {
     FORCE(getiterHelper);
     FORCE(hasnext);
     FORCE(apply_slice);
+    FORCE(applySlice);
+    FORCE(assignSlice);
 
     FORCE(unpackIntoArray);
     FORCE(raiseAttributeError);

src/runtime/objmodel.h

@@ -88,6 +88,9 @@ extern "C" Box* getitem_capi(Box* value, Box* slice) noexcept __attribute__((noi
 extern "C" void setitem(Box* target, Box* slice, Box* value) __attribute__((noinline));
 extern "C" void delitem(Box* target, Box* slice) __attribute__((noinline));
 extern "C" PyObject* apply_slice(PyObject* u, PyObject* v, PyObject* w) noexcept;
+extern "C" PyObject* applySlice(PyObject* u, PyObject* v, PyObject* w);
+extern "C" int assign_slice(PyObject* u, PyObject* v, PyObject* w, PyObject* x) noexcept;
+extern "C" void assignSlice(PyObject* u, PyObject* v, PyObject* w, PyObject* x);
 extern "C" Box* getclsattr(Box* obj, BoxedString* attr) __attribute__((noinline));
 extern "C" Box* getclsattrMaybeNonstring(Box* obj, Box* attr) __attribute__((noinline));
 extern "C" Box* unaryop(Box* operand, int op_type) __attribute__((noinline));

test/test_extension/slots_test.c

@@ -326,7 +326,7 @@ static PyTypeObject slots_tester_map= {
     0,                                  /* tp_getattro */
     0,                                  /* tp_setattro */
     0,                                  /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT,                 /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,                 /* tp_flags */
     0,                   /* tp_doc */
     0,                                  /* tp_traverse */
     0,                                  /* tp_clear */

test/tests/capi_slots.py

@@ -242,3 +242,12 @@ class C(object):
 c = C()
 proxy = weakref.proxy(c)
 print isinstance(proxy, C)
+
+# test if __setslice__ is prioritised over mp_ass_subscript
+class D(slots_test.SlotsTesterMap):
+    def __setslice__(self, *args):
+        print "setslice", args
+d = D(1)
+for i in xrange(10):
+    print i
+    d[1:2] = 1

test/tests/slice.py

@@ -101,11 +101,13 @@ sliceable[3:8]
 both[0]
 both[:]
 both[3:8]
+both[slice(3, 8)]
 both[::2] # this should call __getitem__ since __getslice__ doesn't support steps
 
 both[0] = xrange(2)
 both[:] = xrange(2)
 both[3:8] = xrange(2)
+both[slice(3, 8)] = xrange(2)
 both[::2] = xrange(2)
 
 # Should all call getitem as a fallback
@@ -118,6 +120,7 @@ both[1:2:'c']
 del both[0]
 del both[:]
 del both[3:8]
+del both[slice(3, 8)]
 del both [::2]
 
 try: