Add a check for NULL nlr_top in nlr_jump.

If no nlr_buf has been pushed, and an nlr_jump is called, then control
is transferred to nlr_jump_fail (which should bail out with a fatal
error).

py/nlr.h

@@ -27,6 +27,11 @@ unsigned int nlr_push(nlr_buf_t *);
 void nlr_pop(void);
 void nlr_jump(void *val) __attribute__((noreturn));
 
+// This must be implemented by a port.  It's called by nlr_jump
+// if no nlr buf has been pushed.  It must not return, but rather
+// should bail out with a fatal error.
+void nlr_jump_fail(void *val);
+
 // use nlr_raise instead of nlr_jump so that debugging is easier
 #ifndef DEBUG
 #define nlr_raise(val) nlr_jump(val)

py/nlrthumb.S

@@ -60,6 +60,8 @@ nlr_pop:
 nlr_jump:
     ldr     r3, .L2                 @ load addr of nlr_top
     ldr     r2, [r3]                @ load nlr_top
+    cmp     r2, #0                  @ test if nlr_top is NULL
+    beq     nlr_jump_fail           @ if nlr_top is NULL, transfer control to nlr_jump_fail
     str     r0, [r2, #4]            @ store return value
     ldr     r0, [r2]                @ load prev nlr_buf
     str     r0, [r3]                @ store prev nol_buf into nlr_top (to unlink list)

py/nlrx64.S

@@ -61,6 +61,8 @@ nlr_jump:
 #endif
     movq    %rdi, %rax              # put return value in %rax
     movq    nlr_top(%rip), %rdi     # get nlr_top into %rdi
+    test    %rdi, %rdi              # check for nlr_top being NULL
+    je      .fail                   # fail if nlr_top is NULL
     movq    %rax, 8(%rdi)           # store return value
     movq    (%rdi), %rax            # load prev nlr_buf
     movq    %rax, nlr_top(%rip)     # store prev nlr_buf (to unlink list)
@@ -76,10 +78,14 @@ nlr_jump:
     xorq    %rax, %rax              # clear return register
     inc     %al                     # increase to make 1, non-local return
     ret                             # return
+.fail:
+    movq    %rax, %rdi              # put argument back in first-arg register
+    je      nlr_jump_fail           # transfer control to nlr_jump_fail
 #if !(defined(__APPLE__) && defined(__MACH__))
     .size   nlr_jump, .-nlr_jump
 #endif
 
+    .bss
 #if !(defined(__APPLE__) && defined(__MACH__))
     .local  nlr_top
 #endif
@@ -107,12 +113,21 @@ nlr_push:
     xorq    %rax, %rax              # return 0, normal return
     ret                             # return
 
-/* void nlr_jump(rcx=uint val) */
+/* void nlr_pop() */
+    .globl  nlr_pop
+nlr_pop:
+    movq    nlr_top(%rip), %rax     # get nlr_top into %rax
+    movq    (%rax), %rax            # load prev nlr_buf
+    movq    %rax, nlr_top(%rip)     # store prev nlr_buf (to unlink list)
+    ret                             # return
 
+/* void nlr_jump(rcx=uint val) */
     .globl  nlr_jump
 nlr_jump:
     movq    %rcx, %rax              # put return value in %rax
-    movq    nlr_top(%rip), %rcx     # get nlr_top into %rsi
+    movq    nlr_top(%rip), %rcx     # get nlr_top into %rcx
+    test    %rcx, %rcx              # check for nlr_top being NULL
+    je      .fail                   # fail if nlr_top is NULL
     movq    %rax, 8(%rcx)           # store return value
     movq    (%rcx), %rax            # load prev nlr_buf
     movq    %rax, nlr_top(%rip)     # store prev nlr_buf (to unlink list)
@@ -130,17 +145,13 @@ nlr_jump:
     xorq    %rax, %rax              # clear return register
     inc     %al                     # increase to make 1, non-local return
     ret                             # return
+.fail:
+    movq    %rax, %rcx              # put argument back in first-arg register
+    je      nlr_jump_fail           # transfer control to nlr_jump_fail
 
+    .bss
     .comm   nlr_top,8,8
 
-    /* void nlr_pop() */
-    .globl  nlr_pop
-nlr_pop:
-    movq    nlr_top(%rip), %rax     # get nlr_top into %rax
-    movq    (%rax), %rax            # load prev nlr_buf
-    movq    %rax, nlr_top(%rip)     # store prev nlr_buf (to unlink list)
-    ret                             # return
-
 #endif // !defined(__CYGWIN__)
 
 #endif // __x86_64__

py/nlrx86.S

@@ -60,6 +60,8 @@ _nlr_jump:
 nlr_jump:
 #endif
     mov     nlr_top, %edx           # load nlr_top
+    test    %edx, %edx              # check for nlr_top being NULL
+    je      nlr_jump_fail           # fail if nlr_top is NULL
     mov     4(%esp), %eax           # load return value
     mov     %eax, 4(%edx)           # store return value
     mov     (%edx), %eax            # load prev nlr_top
@@ -78,6 +80,7 @@ nlr_jump:
     .size   nlr_jump, .-nlr_jump
 #endif
 
+    .bss
 #ifndef _WIN32
     .local  nlr_top
 #endif

stm/main.c

@@ -79,6 +79,11 @@ void __fatal_error(const char *msg) {
     }
 }
 
+void nlr_jump_fail(void *val) {
+    printf("FATAL: uncaught exception %p\n", val);
+    __fatal_error("");
+}
+
 STATIC mp_obj_t pyb_config_source_dir = MP_OBJ_NULL;
 STATIC mp_obj_t pyb_config_main = MP_OBJ_NULL;
 

stmhal/main.c

@@ -73,6 +73,11 @@ void __fatal_error(const char *msg) {
     }
 }
 
+void nlr_jump_fail(void *val) {
+    printf("FATAL: uncaught exception %p\n", val);
+    __fatal_error("");
+}
+
 STATIC mp_obj_t pyb_config_source_dir = MP_OBJ_NULL;
 STATIC mp_obj_t pyb_config_main = MP_OBJ_NULL;
 STATIC mp_obj_t pyb_config_usb_mode = MP_OBJ_NULL;

unix-cpy/main.c

+#include <stdlib.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
@@ -74,12 +75,11 @@ int main(int argc, char **argv) {
     return 0;
 }
 
-// for sqrt
-#include <math.h>
-machine_float_t machine_sqrt(machine_float_t x) {
-    return sqrt(x);
-}
-
 mp_import_stat_t mp_import_stat(const char *path) {
     return MP_IMPORT_STAT_NO_EXIST;
 }
+
+void nlr_jump_fail(void *val) {
+    printf("FATAL: uncaught NLR %p\n", val);
+    exit(1);
+}

unix/main.c

@@ -293,6 +293,7 @@ void pre_process_options(int argc, char **argv) {
 }
 
 int main(int argc, char **argv) {
+    nlr_jump(0);
     volatile int stack_dummy;
     stack_top = (void*)&stack_dummy;
 
@@ -447,3 +448,8 @@ int DEBUG_printf(const char *fmt, ...) {
     va_end(ap);
     return ret;
 }
+
+void nlr_jump_fail(void *val) {
+    printf("FATAL: uncaught NLR %p\n", val);
+    exit(1);
+}