mirror of
https://github.com/gcc-mirror/gcc.git
synced 2026-05-06 14:59:39 +02:00
984bdeaa39
In gimple the operation short _8; double _9; _9 = (double) _8; denotes two operations on AArch64. First we have to widen from short to long and then convert this integer to a double. Currently however we only count the widen/truncate operations: (double) _5 6 times vec_promote_demote costs 12 in body (double) _5 12 times vec_promote_demote costs 24 in body but not the actual conversion operation, which needs an additional 12 instructions in the attached testcase. Without this the attached testcase ends up incorrectly thinking that it's beneficial to vectorize the loop at a very high VF = 8 (4x unrolled). Because we can't change the mid-end to account for this the costing code in the backend now keeps track of whether the previous operation was a promotion/demotion and ajdusts the expected number of instructions to: 1. If it's the first FLOAT_EXPR and the precision of the lhs and rhs are different, double it, since we need to convert and promote. 2. If it's the previous operation was a demonition/promotion then reduce the cost of the current operation by the amount we added extra in the last. with the patch we get: (double) _5 6 times vec_promote_demote costs 24 in body (double) _5 12 times vec_promote_demote costs 36 in body which correctly accounts for 30 operations. This fixes the 16% regression in imagick in SPECCPU 2017 reported on Neoverse N2 and using the new generic Armv9-a cost model. gcc/ChangeLog: PR target/110625 * config/aarch64/aarch64.cc (aarch64_vector_costs::add_stmt_cost): Adjust throughput and latency calculations for vector conversions. (class aarch64_vector_costs): Add m_num_last_promote_demote. gcc/testsuite/ChangeLog: PR target/110625 * gcc.target/aarch64/pr110625_4.c: New test. * gcc.target/aarch64/sve/unpack_fcvt_signed_1.c: Add --param aarch64-sve-compare-costs=0. * gcc.target/aarch64/sve/unpack_fcvt_unsigned_1.c: Likewise
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.