Hi DJ, Hi Ian, GCC PR 66827 reports some problems with left shifting a negative value:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66827 Of the problems reported only two remain - in libiberty/regex.c: libiberty/regex.c:6970:11: runtime error: left shift of negative value -1 libiberty/regex.c:7165:4: runtime error: left shift of negative value -1 The patch below fixes these errors by casting the value to be shifted to unsigned before the shift occurs. No regressions were found in the libiberty testsuite or bootstrapping gcc (on an x86_64 target). OK to apply ? Cheers Nick PS: Running the libiberty testsuite with -fsanitize=undefined does throw up a couple more runtime errors: libiberty/cplus-dem.c:503:13: runtime error: signed integer overflow: 922337203 * 10 cannot be represented in type 'int' libiberty/cp-demangle.c:4123:40: runtime error: variable length array bound evaluates to non-positive value 0 libiberty/cp-demangle.c:4124:43: runtime error: variable length array bound evaluates to non-positive value 0 I have not attempted to fix these. The first looks like it is a deliberate piece of coding and the other two look unimportant since the zero sized arrays will never be used. libiberty/ChangeLog 2015-12-18 Nick Clifton <ni...@redhat.com> PR 66827 * regex.c (EXTRACT_NUMBER): Cast sign byte to unsigned before left shifting. Index: libiberty/regex.c =================================================================== --- libiberty/regex.c (revision 231805) +++ libiberty/regex.c (working copy) @@ -685,7 +685,7 @@ # define EXTRACT_NUMBER(destination, source) \ do { \ (destination) = *(source) & 0377; \ - (destination) += SIGN_EXTEND_CHAR (*((source) + 1)) << 8; \ + (destination) += ((unsigned) SIGN_EXTEND_CHAR (*((source) + 1))) << 8; \ } while (0) # endif
