Get rid of the global "last_exc" in favor of sys.exc_info

last_exc was not thread safe, and didn't respect frame-localness.
Now that we have sys.exc_info support we can do this the right way

src/codegen/runtime_hooks.cpp

@@ -253,5 +253,7 @@ void initGlobalFuncs(GlobalState& g) {
     GET(floordiv_float_float);
     GET(mod_float_float);
     GET(pow_float_float);
+
+    GET(dump);
 }
 }

src/codegen/runtime_hooks.h

@@ -50,6 +50,8 @@ struct GlobalFuncs {
     llvm::Value* raise0, *raise3;
 
     llvm::Value* div_float_float, *floordiv_float_float, *mod_float_float, *pow_float_float;
+
+    llvm::Value* dump;
 };
 }
 

src/codegen/unwinding.cpp

@@ -80,9 +80,11 @@ private:
 public:
     void registerCF(CompiledFunction* cf) { cfs.push_back(cf); }
 
+    // addr is the return address of the callsite, so we will check it against
+    // the region (start, end] (opposite-endedness of normal half-open regions)
     CompiledFunction* getCFForAddress(uint64_t addr) {
         for (auto* cf : cfs) {
-            if (cf->code_start <= addr && addr < cf->code_start + cf->code_size)
+            if (cf->code_start < addr && addr <= cf->code_start + cf->code_size)
                 return cf;
         }
         return NULL;

src/codegen/unwinding.h

@@ -26,7 +26,6 @@ const LineInfo* getMostRecentLineInfo();
 class BoxedModule;
 BoxedModule* getCurrentModule();
 
-CompiledFunction* getCFForAddress(uint64_t addr);
 class BoxedDict;
 BoxedDict* getLocals(bool only_user_visible);
 

src/runtime/inline/link_forcer.cpp

@@ -116,6 +116,8 @@ void force() {
     FORCE(mod_float_float);
     FORCE(pow_float_float);
 
+    FORCE(dump);
+
     FORCE(boxFloat);
 
     FORCE(createModule);

src/runtime/stacktrace.cpp

@@ -95,7 +95,6 @@ void unwindExc(Box* exc_obj) {
     abort();
 }
 
-static gc::GCRootHandle last_exc;
 static std::vector<const LineInfo*> last_tb;
 
 void raiseRaw(const ExcInfo& e) __attribute__((__noreturn__));
@@ -115,7 +114,6 @@ void raiseRaw(const ExcInfo& e) {
 void raiseExc(Box* exc_obj) {
     auto entries = getTracebackEntries();
     last_tb = std::move(entries);
-    last_exc = exc_obj;
 
     raiseRaw(ExcInfo(exc_obj->cls, exc_obj, None));
 }
@@ -123,14 +121,14 @@ void raiseExc(Box* exc_obj) {
 // Have a special helper function for syntax errors, since we want to include the location
 // of the syntax error in the traceback, even though it is not part of the execution:
 void raiseSyntaxError(const char* msg, int lineno, int col_offset, const std::string& file, const std::string& func) {
-    last_exc = exceptionNew2(SyntaxError, boxStrConstant(msg));
+    Box* exc = exceptionNew2(SyntaxError, boxStrConstant(msg));
 
     auto entries = getTracebackEntries();
     last_tb = std::move(entries);
     // TODO: leaks this!
     last_tb.push_back(new LineInfo(lineno, col_offset, file, func));
 
-    raiseRaw(ExcInfo(SyntaxError, last_exc, None));
+    raiseRaw(ExcInfo(exc->cls, exc, None));
 }
 
 static void _printTraceback(const std::vector<const LineInfo*>& tb) {
@@ -221,7 +219,7 @@ extern "C" void exit(int code) {
 }
 
 void raise0() {
-    raiseRaw(ExcInfo(last_exc->cls, last_exc, None));
+    raiseRaw(getFrameExcInfo());
 }
 
 bool ExcInfo::matches(BoxedClass* cls) const {

test/tests/sys_excinfo.py

@@ -107,6 +107,26 @@ def f4():
         print "caught attribute error (makes sense, but wrong)"
     except NotImplementedError:
         print "caught not implemented error (weird, but right)"
+
+    # As a variant, if we put the inner exception inside a function call,
+    # it only sets that frame's exc_info.
+    try:
+        try:
+            raise AttributeError()
+        except AttributeError:
+            def thrower():
+                try:
+                    raise NotImplementedError()
+                except:
+                    pass
+            thrower()
+
+            # This time, it should throw the AttributeError
+            raise
+    except AttributeError:
+        print "caught attribute error (right this time)"
+    except NotImplementedError:
+        print "caught not implemented error (wrong this time)"
 f4()
 
 def f5():