http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55184
Bug #: 55184
Summary: Invalid codegen with vectors and casts
Classification: Unclassified
Product: gcc
Version: 4.6.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: math...@gaunard.com
Created attachment 28600
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28600
Testcase
On x86-64, when 128-bit vectors of long or unsigned long are aliased, an
invalid optimization seems to occur and causes only the first element of the
vector to be modified.
Output is correct when compiled without optimization, but fails with -O1 or
greater. Usage of -fno-strict-aliasing doesn't change anything.
The problem doesn't seem to appear in the 4.4, 4.5 and 4.7 series.
Nevertheless I'd like to know all the cases it affects and whether there is a
workaround.
