[pypy-commit] pypy default: Do left-shifts on unsigned numbers to avoid a C99 undefined case (thanks

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r84842:07ecf33562ee
Date: 2016-05-31 10:02 +0200
http://bitbucket.org/pypy/pypy/changeset/07ecf33562ee/

Log:	Do left-shifts on unsigned numbers to avoid a C99 undefined case
	(thanks mjacob)

diff --git a/rpython/translator/c/src/int.h b/rpython/translator/c/src/int.h
--- a/rpython/translator/c/src/int.h
+++ b/rpython/translator/c/src/int.h
@@ -112,15 +112,19 @@
 						r = Py_ARITHMETIC_RIGHT_SHIFT(PY_LONG_LONG,x, (y))
 #define OP_ULLONG_RSHIFT(x,y,r) CHECK_SHIFT_RANGE(y, PYPY_LONGLONG_BIT); \
 						r = (x) >> (y)
-#define OP_LLLONG_RSHIFT(x,y,r)  r = x >> y
+#define OP_LLLONG_RSHIFT(x,y,r) CHECK_SHIFT_RANGE(y, 128); r = (x) >> (y)
 
+/* left-shift of a signed value: C99 makes the result undefined if the
+   value is negative.  Force the left-shift to occur on unsigned instead. */
 #define OP_INT_LSHIFT(x,y,r)    CHECK_SHIFT_RANGE(y, PYPY_LONG_BIT); \
+                                    r = (Signed)(((Unsigned)(x)) << (y))
+#define OP_LLONG_LSHIFT(x,y,r)  CHECK_SHIFT_RANGE(y, PYPY_LONGLONG_BIT); \
+                       r = (long long)(((unsigned long long)(x)) << (y))
+#define OP_LLLONG_LSHIFT(x,y,r) CHECK_SHIFT_RANGE(y, 128); \
+                         r = (__int128)(((unsigned __int128)(x)) << (y))
+
+#define OP_UINT_LSHIFT(x,y,r)   CHECK_SHIFT_RANGE(y, PYPY_LONG_BIT);    \
 							r = (x) << (y)
-#define OP_UINT_LSHIFT(x,y,r)   CHECK_SHIFT_RANGE(y, PYPY_LONG_BIT); \
-							r = (x) << (y)
-#define OP_LLONG_LSHIFT(x,y,r)  CHECK_SHIFT_RANGE(y, PYPY_LONGLONG_BIT); \
-							r = (x) << (y)
-#define OP_LLLONG_LSHIFT(x,y,r)  r = x << y
 #define OP_ULLONG_LSHIFT(x,y,r) CHECK_SHIFT_RANGE(y, PYPY_LONGLONG_BIT); \
 							r = (x) << (y)