py/nlr: Factor out common NLR code to macro and generic funcs in nlr.c.

Each NLR implementation (Thumb, x86, x64, xtensa, setjmp) duplicates a lot
of the NLR code, specifically that dealing with pushing and popping the NLR
pointer to maintain the linked-list of NLR buffers.  This patch factors all
of that code out of the specific implementations into generic functions in
nlr.c, along with a helper macro in nlr.h.  This eliminates duplicated
code.

1 files changed, 51 insertions, 0 deletions

diff --git a/py/nlr.c b/py/nlr.c
new file mode 100644
index 000000000..52d56afb8
--- /dev/null
+++ b/py/nlr.c
@@ -0,0 +1,51 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2017 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/mpstate.h"
+
+#if !MICROPY_NLR_SETJMP
+// When not using setjmp, nlr_push_tail is called from inline asm so needs special c
+#if MICROPY_NLR_X86 && (defined(_WIN32) || defined(__CYGWIN__))
+// On these 32-bit platforms make sure nlr_push_tail doesn't have a leading undersco
+unsigned int nlr_push_tail(nlr_buf_t *nlr) asm("nlr_push_tail");
+#else
+// LTO can't see inside inline asm functions so explicitly mark nlr_push_tail as use
+__attribute__((used)) unsigned int nlr_push_tail(nlr_buf_t *nlr);
+#endif
+#endif
+
+unsigned int nlr_push_tail(nlr_buf_t *nlr) {
+    nlr_buf_t **top = &MP_STATE_THREAD(nlr_top);
+    nlr->prev = *top;
+    MP_NLR_SAVE_PYSTACK(nlr);
+    *top = nlr;
+    return 0; // normal return
+}
+
+void nlr_pop(void) {
+    nlr_buf_t **top = &MP_STATE_THREAD(nlr_top);
+    *top = (*top)->prev;
+}