There are a number of aliasing warnings coming out of tree-ssa-structalias.c
when compiling code in pymol which uses their endianswap.h header at -O3 -Wall.
The warnings are of the form...
In file included from gromacsplugin.cpp:34:
endianswap.h: In function int put_trx_real(md_file*, float):
endianswap.h:117: warning: dereferencing pointer N does break strict-aliasing
rules
endianswap.h:115: note: initialized from here
endianswap.h: In function int trx_real(md_file*, float*):
endianswap.h:143: warning: dereferencing pointer N does break strict-aliasing
rules
endianswap.h:135: warning: dereferencing pointer N does break strict-aliasing
rules
endianswap.h:128: note: initialized from here
endianswap.h:144: warning: dereferencing pointer <anonymous> does break
strict-aliasing rules
endianswap.h:139: warning: dereferencing pointer <anonymous> does break
strict-aliasing rules
endianswap.h:139: note: initialized from here
endianswap.h: In function int write_trr_timestep(void*, const
molfile_timestep_t*):
endianswap.h:117: warning: dereferencing pointer N does break strict-aliasing
rules
endianswap.h:115: note: initialized from here
endianswap.h:117: warning: dereferencing pointer N does break strict-aliasing
rules
endianswap.h:115: note: initialized from here
and don't occur under gcc 4.3. I am wondering if these are valid warnings or a
bug in gcc 4.4? I am attaching the preprocessed source for gromacsplugin.ii.
The weird part is that just compiling the contents of endianswap.h doesn't
trigger the warnings. Also many files in pymol use this header and the errors
appear rather randomly among them. Also I have never seen the 'does break'
warning from tree-ssa-structalias.c, but only the 'will break' warning from
c-common.c.
--
Summary: strange aliasing warnings compiling pymol under gcc 4.4
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: howarth at nitro dot med dot uc dot edu
GCC build triplet: i686-apple-darwin9
GCC host triplet: i686-apple-darwin9
GCC target triplet: i686-apple-darwin9
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39460
