Merge pull request #1123 from undingen/exc_capi_problem

fix two python frame handling crashes

src/codegen/ast_interpreter.cpp

@@ -1857,10 +1857,11 @@ Box* astInterpretFunctionEval(FunctionMetadata* md, Box* globals, Box* boxedLoca
     return v ? v : None;
 }
 
-static Box* astInterpretDeoptInner(FunctionMetadata* md, AST_expr* after_expr, AST_stmt* enclosing_stmt, Box* expr_val,
-                                   FrameStackState frame_state) __attribute__((noinline));
-static Box* astInterpretDeoptInner(FunctionMetadata* md, AST_expr* after_expr, AST_stmt* enclosing_stmt, Box* expr_val,
-                                   FrameStackState frame_state) {
+// caution when changing the function arguments: this function gets called from an assembler wrapper!
+extern "C" Box* astInterpretDeoptFromASM(FunctionMetadata* md, AST_expr* after_expr, AST_stmt* enclosing_stmt,
+                                         Box* expr_val, FrameStackState frame_state) {
+    static_assert(sizeof(FrameStackState) <= 2 * 8, "astInterpretDeopt assumes that all args get passed in regs!");
+
     assert(md);
     assert(enclosing_stmt);
     assert(frame_state.locals);
@@ -1958,11 +1959,6 @@ static Box* astInterpretDeoptInner(FunctionMetadata* md, AST_expr* after_expr, A
     return v ? v : None;
 }
 
-Box* astInterpretDeopt(FunctionMetadata* md, AST_expr* after_expr, AST_stmt* enclosing_stmt, Box* expr_val,
-                       FrameStackState frame_state) {
-    return astInterpretDeoptInner(md, after_expr, enclosing_stmt, expr_val, frame_state);
-}
-
 extern "C" void printExprHelper(Box* obj) {
     Box* displayhook = PySys_GetObject("displayhook");
     if (!displayhook)

src/codegen/ast_interpreter.h

@@ -77,8 +77,9 @@ struct Value {
 Box* astInterpretFunction(FunctionMetadata* f, Box* closure, Box* generator, Box* globals, Box* arg1, Box* arg2,
                           Box* arg3, Box** args);
 Box* astInterpretFunctionEval(FunctionMetadata* cf, Box* globals, Box* boxedLocals);
-Box* astInterpretDeopt(FunctionMetadata* cf, AST_expr* after_expr, AST_stmt* enclosing_stmt, Box* expr_val,
-                       FrameStackState frame_state);
+// this function is implemented in the src/codegen/ast_interpreter_exec.S assembler file
+extern "C" Box* astInterpretDeopt(FunctionMetadata* cf, AST_expr* after_expr, AST_stmt* enclosing_stmt, Box* expr_val,
+                                  FrameStackState frame_state);
 
 struct FrameInfo;
 FrameInfo* getFrameInfoForInterpretedFrame(void* frame_ptr);

src/codegen/ast_interpreter_exec.S

@@ -32,11 +32,36 @@ executeInnerAndSetupFrame:
     sub $16, %rsp
     mov %rdi, -8(%rbp)
     call executeInnerFromASM
-    leave
+    add $16, %rsp
+    pop %rbp
     .cfi_def_cfa            rsp,8
     ret
     .cfi_endproc
 .size executeInnerAndSetupFrame,.-executeInnerAndSetupFrame
 
+// This function is just a small wrapper around astInterpretDeoptFromASM.
+// Our unwinder must be able to detect deopt frames and by writting this wrapper in assembler we can be sure to correctly
+// detect the frame independent of compiler optimizations because this function will always appear in the call stack.
+//
+// Box* astInterpretDeopt(FunctionMetadata* cf, AST_expr* after_expr, AST_stmt* enclosing_stmt, Box* expr_val,
+//                        FrameStackState frame_state);
+.text
+.globl astInterpretDeopt
+.type astInterpretDeopt,@function
+.align 16
+astInterpretDeopt:
+    .cfi_startproc
+    push %rbp
+    .cfi_def_cfa_offset     16
+    .cfi_offset             rbp,-16
+    mov %rsp, %rbp
+    .cfi_def_cfa_register   rbp
+    call astInterpretDeoptFromASM
+    pop %rbp
+    .cfi_def_cfa            rsp,8
+    ret
+    .cfi_endproc
+.size astInterpretDeopt,.-astInterpretDeopt
+
 .section .note.GNU-stack,"",%progbits // we don't need executable stack
 

src/codegen/irgen/irgenerator.cpp

@@ -3058,6 +3058,7 @@ public:
             // just not created an Invoke and let the exception machinery propagate it for us.
             assert(irstate->getExceptionStyle() == CAPI);
             builder->CreateCall3(g.funcs.PyErr_Restore, exc_type, exc_value, exc_traceback);
+            builder->CreateCall(g.funcs.deinitFrame, irstate->getFrameInfoVar());
             builder->CreateRet(getNullPtr(g.llvm_value_type_ptr));
         }
 

test/tests/exceptions_test2.py

+# this test caused crashes because of a missing deinitFrame call in the LLVM tier when compiling funcs in CAPI mode
+def next(x):
+    1/x
+
+def foo(x):
+    try:
+        next(x)
+    except Exception as e:
+        print "exc", e
+
+foo(1)
+foo(0)