gcc/libstdc++-v3
Matthias Kretz e77f314ccd libstdc++: Fix find_last_set(simd_mask) to ignore padding bits
With the change to the AVX512 find_last_set implementation, the change
to AVX512 operator!= is unnecessary. However, the latter was not
producing optimal code and unnecessarily set the padding bits. In
theory, the compiler could determine that with the new !=
implementation, the bit operation for clearing the padding bits is a
no-op and can be elided.

Signed-off-by: Matthias Kretz <m.kretz@gsi.de>

libstdc++-v3/ChangeLog:

	PR libstdc++/115454
	* include/experimental/bits/simd_x86.h (_S_not_equal_to): Use
	neq comparison instead of bitwise negation after eq.
	(_S_find_last_set): Clear unused high bits before computing
	bit_width.
	* testsuite/experimental/simd/pr115454_find_last_set.cc: New
	test.

(cherry picked from commit 1340ddea0158de3f49aeb75b4013e5fc313ff6f4)
2024-06-20 13:28:06 +02:00
..
config libstdc++: Update powerpc-linux-gnu baseline_symbols 2024-05-03 15:39:00 +02:00
doc libstdc++: Replace link to gcc-4.3.2 docs in manual [PR115269] 2024-06-01 11:01:37 +01:00
include libstdc++: Fix find_last_set(simd_mask) to ignore padding bits 2024-06-20 13:28:06 +02:00
libsupc++ libstdc++: Fix declaration of posix_memalign for freestanding 2024-06-14 15:39:27 +01:00
po Update copyright years. 2024-01-03 12:19:35 +01:00
python libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318] 2024-01-17 11:49:11 +00:00
scripts libstdc++: Rename man pages to use '::' instead of '_' 2024-04-25 18:38:44 +01:00
src libstdc++: Build libbacktrace and 19_diagnostics/stacktrace with -funwind-tables [PR111641] 2024-06-04 09:10:24 +02:00
testsuite libstdc++: Fix find_last_set(simd_mask) to ignore padding bits 2024-06-20 13:28:06 +02:00
acinclude.m4 Fix up duplicated words mostly in comments, part 1 2024-04-02 13:39:11 +02:00
aclocal.m4
ChangeLog Daily bump. 2024-06-15 00:22:06 +00:00
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ChangeLog-2023 Rotate ChangeLog files. 2024-01-03 11:29:39 +01:00
config.h.in libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318] 2024-01-17 11:49:11 +00:00
configure libstdc++, Darwin: Handle a linker warning [PR112397]. 2024-02-19 20:14:34 +00:00
configure.ac libstdc++, Darwin: Handle a linker warning [PR112397]. 2024-02-19 20:14:34 +00:00
configure.host Fix up duplicated words mostly in comments, part 1 2024-04-02 13:39:11 +02:00
crossconfig.m4
fragment.am
linkage.m4 libstdc++: Remove handling for underscore-prefixed libm functions [PR111638] 2023-11-11 00:41:08 +00:00
Makefile.am Update copyright years. 2024-01-03 12:19:35 +01:00
Makefile.in Allow overriding EXPECT 2023-12-22 10:24:56 +00:00
README

file: libstdc++-v3/README

New users may wish to point their web browsers to the file
index.html in the 'doc/html' subdirectory.  It contains brief
building instructions and notes on how to configure the library in
interesting ways.