On Fri, Feb 17, 2023 at 8:43 PM Takayuki 'January June' Suwa <jjsuwa_sys3...@yahoo.co.jp> wrote: > > Register-register move instructions that can be easily seen as > unnecessary by the human eye may remain in the compiled result. > For example: > > /* example */ > double test(double a, double b) { > return __builtin_copysign(a, b); > } > > test: > add.n a3, a3, a3 > extui a5, a5, 31, 1 > ssai 1 > ;; Be in the same BB > src a7, a5, a3 ;; Replacing the destination doesn't > ;; violate any constraints of the > ;; operands > ;; No CALL insns in this span > ;; Both A3 and A7 are irrelevant to > ;; insns in this span > mov.n a3, a7 ;; An unnecessary reg-reg move > ;; A7 is not used after this > ret.n > > The last two instructions above, excluding the return instruction, > could be done like this: > > src a3, a5, a3 > > This symptom often occurs when handling DI/DFmode values with SImode > instructions. This patch solves the above problem using peephole2 > pattern. > > gcc/ChangeLog: > > * config/xtensa/xtensa.md: New peephole2 pattern that eliminates > the occurrence of general-purpose register used only once and for > transferring intermediate value. > > gcc/testsuite/ChangeLog: > > * gcc.target/xtensa/elim_GP_regmove_[01].c: New. > --- > gcc/config/xtensa/xtensa.md | 46 +++++++++++++++++++ > .../gcc.target/xtensa/elim_GP_regmove_0.c | 23 ++++++++++ > .../gcc.target/xtensa/elim_GP_regmove_1.c | 10 ++++ > 3 files changed, 79 insertions(+) > create mode 100644 gcc/testsuite/gcc.target/xtensa/elim_GP_regmove_0.c > create mode 100644 gcc/testsuite/gcc.target/xtensa/elim_GP_regmove_1.c
Regtested for target=xtensa-linux-uclibc, no new regressions. Committed to master. -- Thanks. -- Max