Clear the exc_info when resuming a generator

src/analysis/type_analysis.cpp

@@ -372,6 +372,7 @@ private:
                 return UNKNOWN;
             case AST_LangPrimitive::NONE:
             case AST_LangPrimitive::SET_EXC_INFO:
+            case AST_LangPrimitive::UNCACHE_EXC_INFO:
                 return NONE;
             case AST_LangPrimitive::NONZERO:
                 return BOOL;

src/codegen/ast_interpreter.cpp

@@ -562,6 +562,10 @@ Value ASTInterpreter::visit_langPrimitive(AST_LangPrimitive* node) {
 
         getFrameInfo()->exc = ExcInfo(type.o, value.o, traceback.o);
         v = None;
+    } else if (node->opcode == AST_LangPrimitive::UNCACHE_EXC_INFO) {
+        assert(node->args.empty());
+        getFrameInfo()->exc = ExcInfo(NULL, NULL, NULL);
+        v = None;
     } else
         RELEASE_ASSERT(0, "not implemented");
     return v;

src/codegen/irgen/irgenerator.cpp

@@ -638,6 +638,22 @@ private:
 
                 return getNone();
             }
+            case AST_LangPrimitive::UNCACHE_EXC_INFO: {
+                assert(node->args.empty());
+
+                auto* builder = emitter.getBuilder();
+
+                llvm::Value* frame_info = irstate->getFrameInfoVar();
+                llvm::Value* exc_info = builder->CreateConstInBoundsGEP2_32(frame_info, 0, 0);
+                assert(exc_info->getType() == g.llvm_excinfo_type->getPointerTo());
+
+                llvm::Constant* v = embedConstantPtr(0, g.llvm_value_type_ptr);
+                builder->CreateStore(v, builder->CreateConstInBoundsGEP2_32(exc_info, 0, 0));
+                builder->CreateStore(v, builder->CreateConstInBoundsGEP2_32(exc_info, 0, 1));
+                builder->CreateStore(v, builder->CreateConstInBoundsGEP2_32(exc_info, 0, 2));
+
+                return getNone();
+            }
             default:
                 RELEASE_ASSERT(0, "%d", node->opcode);
         }

src/core/ast.cpp

@@ -1454,6 +1454,9 @@ bool PrintVisitor::visit_langprimitive(AST_LangPrimitive* node) {
         case AST_LangPrimitive::SET_EXC_INFO:
             printf("SET_EXC_INFO");
             break;
+        case AST_LangPrimitive::UNCACHE_EXC_INFO:
+            printf("UNCACHE_EXC_INFO");
+            break;
         default:
             RELEASE_ASSERT(0, "%d", node->opcode);
     }

src/core/ast.h

@@ -997,6 +997,7 @@ public:
         NONE,
         NONZERO,
         SET_EXC_INFO,
+        UNCACHE_EXC_INFO,
     } opcode;
     std::vector<AST_expr*> args;
 

src/core/cfg.cpp

@@ -1006,7 +1006,13 @@ private:
         rtn->lineno = node->lineno;
         rtn->col_offset = node->col_offset;
         rtn->value = remapExpr(node->value);
-        return rtn;
+
+        InternedString node_name(nodeName(rtn));
+        pushAssign(node_name, rtn);
+
+        push_back(makeExpr(new AST_LangPrimitive(AST_LangPrimitive::UNCACHE_EXC_INFO)));
+
+        return makeName(node_name, AST_TYPE::Load, node->lineno);
     }
 
     AST_expr* remapExpr(AST_expr* node, bool wrap_with_assign = true) {

test/tests/generator_tracebacks.py

-# expected: fail
-# - wip
-
 # Generators participate in the notional Python stack just like normal function calls do,
 # even if we implement them using separate C stacks.
 #
@@ -8,6 +5,7 @@
 # get inherited when we go into a generator
 
 # exc_info gets passed into generators (at both begin and send()) and cleared like normal on the way out:
+import sys
 def f12():
     print
     print "f12"
@@ -25,6 +23,7 @@ def f12():
         print "after KeyError:", sys.exc_info()[0]
         yield 2
 
+    print list(g())
     try:
         raise AttributeError()
     except:
@@ -32,6 +31,7 @@ def f12():
 
     i = g()
     i.next()
+    print list(g())
     try:
         1/0
     except: