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Jakub Jelinek bea07159d1 vectorizer: Fix up vectorization using WIDEN_MINUS_EXPR [PR102124]
The following testcase is miscompiled on aarch64-linux at -O3 since the
introduction of WIDEN_MINUS_EXPR.
The problem is if the inner type (half_type) is unsigned and the result
type in which the subtraction is performed (type) has precision more than
twice as larger as the inner type's precision.
For other widening operations like WIDEN_{PLUS,MULT}_EXPR, if half_type
is unsigned, the addition/multiplication result in itype is also unsigned
and needs to be zero-extended to type.
But subtraction is special, even when half_type is unsigned, the subtraction
behaves as signed (also regardless of whether the result type is signed or
unsigned), 0xfeU - 0xffU is -1 or 0xffffffffU, not 0x0000ffff.

I think it is better not to use mixed signedness of types in
WIDEN_MINUS_EXPR (have unsigned vector of operands and signed result
vector), so this patch instead adds another cast to make sure we always
sign-extend the result from itype to type if type is wider than itype.

2021-09-01  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/102124
	* tree-vect-patterns.c (vect_recog_widen_op_pattern): For ORIG_CODE
	MINUS_EXPR, if itype is unsigned with smaller precision than type,
	add an extra cast to signed variant of itype to ensure sign-extension.

	* gcc.dg/torture/pr102124.c: New test.
2021-09-01 13:40:43 +02:00
INSTALL
c++tools Daily bump. 2021-07-22 00:16:46 +00:00
config Daily bump. 2021-08-19 00:16:42 +00:00
contrib Daily bump. 2021-08-31 00:16:50 +00:00
fixincludes Daily bump. 2021-08-31 00:16:50 +00:00
gcc vectorizer: Fix up vectorization using WIDEN_MINUS_EXPR [PR102124] 2021-09-01 13:40:43 +02:00
gnattools
gotools
include Daily bump. 2021-08-24 00:17:00 +00:00
intl Daily bump. 2021-06-15 00:16:37 +00:00
libada
libatomic Daily bump. 2021-07-22 00:16:46 +00:00
libbacktrace Daily bump. 2021-08-14 00:16:29 +00:00
libcc1 Daily bump. 2021-08-18 00:16:48 +00:00
libcody
libcpp Daily bump. 2021-09-01 00:16:58 +00:00
libdecnumber
libffi Daily bump. 2021-08-31 00:16:50 +00:00
libgcc Daily bump. 2021-09-01 00:16:58 +00:00
libgfortran Daily bump. 2021-08-28 00:16:42 +00:00
libgo libgo: various fixes for Solaris support 2021-08-14 17:34:52 -07:00
libgomp Daily bump. 2021-08-24 00:17:00 +00:00
libiberty Daily bump. 2021-08-30 00:16:44 +00:00
libitm Daily bump. 2021-06-18 00:16:58 +00:00
libobjc
liboffloadmic
libphobos Daily bump. 2021-08-31 00:16:50 +00:00
libquadmath
libsanitizer Daily bump. 2021-08-12 00:16:28 +00:00
libssp
libstdc++-v3 Daily bump. 2021-09-01 00:16:58 +00:00
libvtv
lto-plugin Daily bump. 2021-06-26 00:16:39 +00:00
maintainer-scripts
zlib
.dir-locals.el dir-locals: Use https for bug references 2021-07-20 11:40:34 +01:00
.gitattributes
.gitignore Add cscope.out to git ignore. 2021-06-24 16:51:40 +05:30
ABOUT-NLS
COPYING
COPYING.LIB
COPYING.RUNTIME
COPYING3
COPYING3.LIB
ChangeLog Daily bump. 2021-09-01 00:16:58 +00:00
ChangeLog.jit
ChangeLog.tree-ssa
MAINTAINERS MAINTAINERS: Add YunQiang Su for write after approval 2021-09-01 18:19:12 +08:00
Makefile.def gdb: Add a dependency between gdb and libbacktrace 2021-08-31 10:00:22 +01:00
Makefile.in gdb: Add a dependency between gdb and libbacktrace 2021-08-31 10:00:22 +01:00
Makefile.tpl configure: Allow host fragments to react to --enable-host-shared. 2021-08-18 19:46:32 +01:00
README
ar-lib
compile
config-ml.in
config.guess
config.rpath
config.sub
configure Darwin, config: Revise host config fragment. 2021-07-09 17:35:57 +01:00
configure.ac Darwin, config: Revise host config fragment. 2021-07-09 17:35:57 +01:00
depcomp
install-sh
libtool-ldflags
libtool.m4
ltgcc.m4
ltmain.sh
ltoptions.m4
ltsugar.m4
ltversion.m4
lt~obsolete.m4
missing
mkdep
mkinstalldirs
move-if-change
multilib.am
symlink-tree
test-driver
ylwrap

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