Re: [PATCH] PR tree-optimization/83907: Improved memset handling in strlen pass.
On 2/20/2022 9:51 AM, Roger Sayle wrote: This patch implements the missed optimization enhancement PR 83907, by handling memset with a constant byte value in tree-ssa's strlen optimization pass. Effectively, this treats memset(dst,'x',3) as it would memcpy(dst,"xxx",3). This patch also includes a tweak to handle_store to address another missed optimization observed in the related test case pr83907-2.c. The consecutive byte stores to memory get coalesced into a vector write of a vector const, but unfortunately tree-ssa-strlen's handle_store didn't previously handle the (unusual) case where the stored "string" starts with a zero byte but also contains non-zero bytes. This patch has been tested on x86_64-pc-linux-gnu with make bootstrap and make -k check with no new failures. Ok for mainline? 2022-02-20 Roger Sayle gcc/ChangeLog PR tree-optimization/83907 * tree-ssa-strlen.cc (handle_builtin_memset): Record a strinfo for memset with an constant char value. (handle_store): Improved handling of stores with a first byte of zero, but not storing_all_zeros_p. gcc/testsuite/ChangeLog PR tree-optimization/83907 * gcc.dg/tree-ssa/pr83907-1.c: New test case. * gcc.dg/tree-ssa/pr83907-2.c: New test case. OK after a re-test. Thanks for the ping. jeff
RE: [PATCH] PR tree-optimization/83907: Improved memset handling in strlen pass.
Hi Jeff, Any chance you could take a look at this patch, now that we're back in stage1? Thanks in advance, Roger > -Original Message- > From: Jeff Law > Sent: 02 March 2022 19:33 > To: Roger Sayle ; gcc-patches@gcc.gnu.org > Subject: Re: [PATCH] PR tree-optimization/83907: Improved memset handling in > strlen pass. > > On 2/20/2022 9:51 AM, Roger Sayle wrote: > > This patch implements the missed optimization enhancement PR 83907, by > > handling memset with a constant byte value in tree-ssa's strlen > > optimization pass. Effectively, this treats memset(dst,'x',3) as it > > would memcpy(dst,"xxx",3). > > > > This patch also includes a tweak to handle_store to address another > > missed optimization observed in the related test case pr83907-2.c. > > The consecutive byte stores to memory get coalesced into a vector > > write of a vector const, but unfortunately tree-ssa-strlen's > > handle_store didn't previously handle the (unusual) case where the > > stored "string" starts with a zero byte but also contains non-zero > > bytes. > > > > This patch has been tested on x86_64-pc-linux-gnu with make bootstrap > > and make -k check with no new failures. Ok for mainline? > > > > > > 2022-02-20 Roger Sayle > > > > gcc/ChangeLog > > PR tree-optimization/83907 > > * tree-ssa-strlen.cc (handle_builtin_memset): Record a strinfo > > for memset with an constant char value. > > (handle_store): Improved handling of stores with a first byte > > of zero, but not storing_all_zeros_p. > > > > gcc/testsuite/ChangeLog > > PR tree-optimization/83907 > > * gcc.dg/tree-ssa/pr83907-1.c: New test case. > > * gcc.dg/tree-ssa/pr83907-2.c: New test case. > Deferring to stage1. > jeff
Re: [PATCH] PR tree-optimization/83907: Improved memset handling in strlen pass.
On 2/20/2022 9:51 AM, Roger Sayle wrote: This patch implements the missed optimization enhancement PR 83907, by handling memset with a constant byte value in tree-ssa's strlen optimization pass. Effectively, this treats memset(dst,'x',3) as it would memcpy(dst,"xxx",3). This patch also includes a tweak to handle_store to address another missed optimization observed in the related test case pr83907-2.c. The consecutive byte stores to memory get coalesced into a vector write of a vector const, but unfortunately tree-ssa-strlen's handle_store didn't previously handle the (unusual) case where the stored "string" starts with a zero byte but also contains non-zero bytes. This patch has been tested on x86_64-pc-linux-gnu with make bootstrap and make -k check with no new failures. Ok for mainline? 2022-02-20 Roger Sayle gcc/ChangeLog PR tree-optimization/83907 * tree-ssa-strlen.cc (handle_builtin_memset): Record a strinfo for memset with an constant char value. (handle_store): Improved handling of stores with a first byte of zero, but not storing_all_zeros_p. gcc/testsuite/ChangeLog PR tree-optimization/83907 * gcc.dg/tree-ssa/pr83907-1.c: New test case. * gcc.dg/tree-ssa/pr83907-2.c: New test case. Deferring to stage1. jeff
