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[PATCH, ARM][0/6] LDRD/STRD generation - introduction
- From: "Greta Yorsh" <Greta dot Yorsh at arm dot com>
- To: <gcc-patches at gcc dot gnu dot org>
- Cc: <nickc at redhat dot com>, "Richard Earnshaw" <Richard dot Earnshaw at arm dot com>, <paul at codesourcery dot com>, "Ramana Radhakrishnan" <Ramana dot Radhakrishnan at arm dot com>
- Date: Mon, 7 Nov 2011 11:42:23 -0000
- Subject: [PATCH, ARM][0/6] LDRD/STRD generation - introduction
The following sequence of patches enables generation of LDRD/STRD
instructions for Cortex-A15 with -O2 and for all Cortex-A CPUs with -Os when
profitable. This almost always improves code size and is expected to improve
performance on Cortex-A15.
[0/6] LDRD/STRD generation - introduction (this email)
[1/6] Merge LDR/STR into LDRD/STRD with -O2 in Thumb (1-ldrdstrd.patch)
[2/6] Merge LDR/STR into LDRD/STRD with -O2 in ARM (2-output-double.patch)
[3/6] Merge LDR/STR into LDRD/STRD with -Os (3-size.patch)
[4/6] Improve peepholes for generating LDM with commutative operators
(4-ldm-commute.patch)
[5/6] Generate LDRD/STRD for internal memcpy (5-internal-memcpy.patch)
[6/6] Tests for LDRD/STRD/LDM/STM generation for Cortex-A9/A15
(6-cortexa-tests.patch, creatests.py)
The patches are to be applied in the given order.
Testing and benchmarking is in progress:
* Passed all tests in check-gcc without regressions on qemu for target
arm-none-eabi built with newlib and various configurations of
A15/A9/Thumb/ARM (see ^note).
* Successful cross-build of arm-none-linux-gnueabi with eglibc and
A15/A9/Thumb/ARM
* Successful bootstrap on Cortex-A9 Tegra Linux Ubuntu board (A9 Thumb/ARM).
* Cross-built Spec2k using arm-none-linux-gnueabi compiler in several
configurations of A9/A15/Thumb/ARM.
* Ran CINT Spec2K on Cortex-A9 VE2 Linux board. No regression in runtime
between the files built with the trunk and the patched versions of the
compiler (A9 Thumb/ARM). There are some LDRD/STRD instructions in the
patched version.
* A brief look at CSiBE benchmark: the results show small improvement in
code size with a small increase in compilation time for most benchmarks.
I am working on more benchmark results and their detailed analysis.
-- Greta
(^note) The patch has accidently fixed or masked a failure in a regression
test of vector shuffle:
FAIL->PASS: gcc.dg/torture/vshuf-v8sf.c -O2 execution test (an abort
statement is executed)
The test fails when the compiler is configured with cortex-a15 thumb neon
and softfp, gcc trunk r180197. After the patch is applied, the test passes.