https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86055
Bug ID: 86055
Summary: Bitshifts temporarly change uint32_t to int32_t on
x86_64 Mac OS
Product: gcc
Version: 8.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: guicrith at gmail dot com
Target Milestone: ---
Created attachment 44238
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44238&action=edit
Simple test program source, no dependancys.
Right-shifting a negative value is implementation-defined and not recommended
by good coding practice. Wikipedia
The same behavior is occuring with a uint32_t, but it should be impossible for
it to be negative.
Under the existing C rules uint16_t should be promoted to int64_t(the native
int type for x86_64) before bitshifting.
It seems to be taking the signed part of int64_t without the 64 bits part.
x86_64 Mac OS 10.13.5 gcc version 8.1.0 (Homebrew GCC 8.1.0)
