Hi Suwa-san, On Mon, Jan 16, 2023 at 8:12 PM Takayuki 'January June' Suwa <jjsuwa_sys3...@yahoo.co.jp> wrote: > > In the case of the CALL0 ABI, values that must be retained before and > after function calls are placed in the callee-saved registers (A12 > through A15) and referenced later. However, it is often the case that > the save and the reference are each only once and a simple register- > register move (the frame pointer is needed to recover the stack pointer > and must be excluded). > > e.g. in the following example, if there are no other occurrences of > register A14: > > ;; before > ; prologue { > ... > s32i.n a14, sp, 16 > ... > ; } prologue > ... > mov.n a14, a6 > ... > call0 foo > ... > mov.n a8, a14 > ... > ; epilogue { > ... > l32i.n a14, sp, 16 > ... > ; } epilogue > > It can be possible like this: > > ;; after > ; prologue { > ... > (deleted) > ... > ; } prologue > ... > s32i.n a6, sp, 16 > ... > call0 foo > ... > l32i.n a8, sp, 16 > ... > ; epilogue { > ... > (deleted) > ... > ; } epilogue > > This patch introduces a new peephole2 pattern that implements the above. > > gcc/ChangeLog: > > * config/xtensa/xtensa.md: New peephole2 pattern that eliminates > the use of callee-saved register that saves and restores only once > for other register, by using its stack slot directly. > --- > gcc/config/xtensa/xtensa.md | 60 +++++++++++++++++++++++++++++++++++++ > 1 file changed, 60 insertions(+)
There's still a few regressions in tests with -fcompare-debug because code generated with -g and without it is different: +FAIL: gcc.dg/pr41241.c (test for excess errors) +FAIL: gcc.dg/pr48159-1.c (test for excess errors) +FAIL: gcc.dg/pr65521.c (test for excess errors) +FAIL: gcc.dg/torture/pr42878-1.c -O2 (test for excess errors) +FAIL: gcc.dg/torture/pr42878-1.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions (test for excess errors) +FAIL: gcc.dg/torture/pr42878-1.c -O3 -g (test for excess errors) +FAIL: gcc.dg/torture/pr42878-1.c -Os (test for excess errors) +FAIL: gcc.dg/torture/pr42878-1.c -O2 -flto -fno-use-linker-plugin -flto-partition=none (test for excess errors) E.g. check the following test with -g0 and -g: gcc/cc1 gcc/testsuite/gcc.dg/torture/pr42878-1.c -mlongcalls -mtext-section-literals -fdiagnostics-plain-output -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions -- Thanks. -- Max