On Wed, 15 Nov 2017, Tamar Christina wrote: > > > > -----Original Message----- > > From: Richard Biener [mailto:rguent...@suse.de] > > Sent: Wednesday, November 15, 2017 08:24 > > To: Tamar Christina <tamar.christ...@arm.com> > > Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>; l...@redhat.com; > > i...@airs.com > > Subject: Re: [PATCH][GCC][mid-end] Allow larger copies when target > > supports unaligned access [Patch (1/2)] > > > > On Tue, 14 Nov 2017, Tamar Christina wrote: > > > > > Hi All, > > > > > > This patch allows larger bitsizes to be used as copy size when the > > > target does not have SLOW_UNALIGNED_ACCESS. > > > > > > fun3: > > > adrp x2, .LANCHOR0 > > > add x2, x2, :lo12:.LANCHOR0 > > > mov x0, 0 > > > sub sp, sp, #16 > > > ldrh w1, [x2, 16] > > > ldrb w2, [x2, 18] > > > add sp, sp, 16 > > > bfi x0, x1, 0, 8 > > > ubfx x1, x1, 8, 8 > > > bfi x0, x1, 8, 8 > > > bfi x0, x2, 16, 8 > > > ret > > > > > > is turned into > > > > > > fun3: > > > adrp x0, .LANCHOR0 > > > add x0, x0, :lo12:.LANCHOR0 > > > sub sp, sp, #16 > > > ldrh w1, [x0, 16] > > > ldrb w0, [x0, 18] > > > strh w1, [sp, 8] > > > strb w0, [sp, 10] > > > ldr w0, [sp, 8] > > > add sp, sp, 16 > > > ret > > > > > > which avoids the bfi's for a simple 3 byte struct copy. > > > > > > Regression tested on aarch64-none-linux-gnu and x86_64-pc-linux-gnu and > > no regressions. > > > > > > This patch is just splitting off from the previous combined patch with > > > AArch64 and adding a testcase. > > > > > > I assume Jeff's ACK from > > > https://gcc.gnu.org/ml/gcc-patches/2017-08/msg01523.html is still valid as > > the code did not change. > > > > Given your no_slow_unalign isn't mode specific can't you use the existing > > non_strict_align? > > No because non_strict_align checks if the target supports unaligned access at > all, > > This no_slow_unalign corresponds instead to the target slow_unaligned_access > which checks that the access you want to make has a greater cost than doing an > aligned access. ARM for instance always return 1 (value of STRICT_ALIGNMENT) > for slow_unaligned_access while for non_strict_align it may return 0 or 1 > based > on the options provided to the compiler. > > The problem is I have no way to test STRICT_ALIGNMENT or slow_unaligned_access > So I had to hardcode some targets that I know it does work on.
I see. But then the slow_unaligned_access implementation should use non_strict_align as default somehow as SLOW_UNALIGNED_ACCESS is defaulted to STRICT_ALIGN. Given that SLOW_UNALIGNED_ACCESS has different values for different modes it would also make sense to be more specific for the testcase in question, like word_mode_slow_unaligned_access to tell this only applies to word_mode? Thanks, Richard. > Thanks, > Tamar > > > > Otherwise the expr.c change looks ok. > > > > Thanks, > > Richard. > > > > > Thanks, > > > Tamar > > > > > > > > > gcc/ > > > 2017-11-14 Tamar Christina <tamar.christ...@arm.com> > > > > > > * expr.c (copy_blkmode_to_reg): Fix bitsize for targets > > > with fast unaligned access. > > > * doc/sourcebuild.texi (no_slow_unalign): New. > > > > > > gcc/testsuite/ > > > 2017-11-14 Tamar Christina <tamar.christ...@arm.com> > > > > > > * gcc.dg/struct-simple.c: New. > > > * lib/target-supports.exp > > > (check_effective_target_no_slow_unalign): New. > > > > > > > > > > -- > > Richard Biener <rguent...@suse.de> > > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, > > HRB 21284 (AG Nuernberg) > > -- Richard Biener <rguent...@suse.de> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
