On Wed, Jun 15, 2022 at 5:23 AM Takayuki 'January June' Suwa <jjsuwa_sys3...@yahoo.co.jp> wrote: > > On 2022/06/15 5:17, Max Filippov wrote: > > Hi Suwa-san, > hi! > > > This change results in a bunch of new regression test failures: > > The code generated for e.g. gcc.c-torture/execute/921208-2.c looks like > > this: > oh, PICed... > > indirect (incl. via function pointer, virtual functions and of course PIC > ones in Xtensa ISA) sibcalls must be avoided if pointer to the target cannot > be retained during function epilogue. > otherwise, it will be look like this: > > callx0 a14 > > l32i.n a0, sp, 12 > > l32i.n a14, sp, 0 // restored by the epilogue because A14 is > > callee-saved > > mov.n a4, a12 > > mov.n a5, a13 > > l32i.n a12, sp, 8 > > l32i.n a13, sp, 4 > > l32r a3, .LC4 > > movi.n a2, 0 > > addi sp, sp, 16 > > jx a14 // but A14 pointed to g@PLT in this > > function... > > luckily, no role is assigned from A9 to A11 in call0 ABI (A9 is already used > inside of the pro/epilogue), and the "split2" stage is prior to > "pro_and_epilogue"... > > === > This patch introduces support for sibling call optimization, when call0 > ABI is in effect. > > gcc/ChangeLog: > > * config/xtensa/xtensa-protos.h (xtensa_prepare_expand_call, > xtensa_emit_sibcall): New prototypes. > (xtensa_expand_epilogue): Add new argument that specifies whether > or not sibling call. > * config/xtensa/xtensa.cc (TARGET_FUNCTION_OK_FOR_SIBCALL): > New macro definition. > (xtensa_prepare_expand_call): New function in order to share > the common code. > (xtensa_emit_sibcall, xtensa_function_ok_for_sibcall): > New functions. > (xtensa_expand_epilogue): Add new argument sibcall_p and use it > for sibling call handling. > * config/xtensa/xtensa.md (call, call_value): > Use xtensa_prepare_expand_call. > (call_internal, call_value_internal): > Add the condition in order to be disabled if sibling call. > (sibcall, sibcall_value, sibcall_epilogue): New expansions. > (sibcall_internal, sibcall_value_internal): New insn patterns, > and split ones in order to take care of the indirect sibcalls. > > gcc/testsuite/ChangeLog: > > * gcc.target/xtensa/sibcalls.c: New. > --- > gcc/config/xtensa/xtensa-protos.h | 4 +- > gcc/config/xtensa/xtensa.cc | 58 +++++++++++++- > gcc/config/xtensa/xtensa.md | 93 ++++++++++++++++++---- > gcc/testsuite/gcc.target/xtensa/sibcalls.c | 20 +++++ > 4 files changed, 155 insertions(+), 20 deletions(-) > create mode 100644 gcc/testsuite/gcc.target/xtensa/sibcalls.c
Regtested for target=xtensa-linux-uclibc, no new regressions. Committed to master. -- Thanks. -- Max
