From 10351a5dade506b85992c0d9f029cf37c8e90ef4 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Tue, 5 Dec 2023 09:35:57 +0000 Subject: [PATCH 046/144] Add a target hook for sibcall epilogues Reference: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=2e0aefa77157396acb48833407637303edba450a Epilogues for sibling calls are generated using the sibcall_epilogue pattern. One disadvantage of this approach is that the target doesn't know which call the epilogue is for, even though the code that generates the pattern has the call to hand. Although call instructions are currently rtxes, and so could be passed as an operand to the pattern, the main point of introducing rtx_insn was to move towards separating the rtx and insn types (a good thing IMO). There also isn't an existing practice of passing genuine instructions (as opposed to labels) to instruction patterns. This patch therefore adds a hook that can be defined as an alternative to sibcall_epilogue. The advantage is that it can be passed the call; the disadvantage is that it can't use .md conveniences like generating instructions from textual patterns (although most epilogues are too complex to benefit much from that anyway). gcc/ * doc/tm.texi.in: Add TARGET_EMIT_EPILOGUE_FOR_SIBCALL. * doc/tm.texi: Regenerate. * target.def (emit_epilogue_for_sibcall): New hook. * calls.cc (can_implement_as_sibling_call_p): Use it. * function.cc (thread_prologue_and_epilogue_insns): Likewise. (reposition_prologue_and_epilogue_notes): Likewise. * config/aarch64/aarch64-protos.h (aarch64_expand_epilogue): Take an rtx_call_insn * rather than a bool. * config/aarch64/aarch64.cc (aarch64_expand_epilogue): Likewise. (TARGET_EMIT_EPILOGUE_FOR_SIBCALL): Define. * config/aarch64/aarch64.md (epilogue): Update call. (sibcall_epilogue): Delete. --- gcc/calls.cc | 3 ++- gcc/config/aarch64/aarch64-protos.h | 2 +- gcc/config/aarch64/aarch64.cc | 11 +++++++---- gcc/config/aarch64/aarch64.md | 11 +---------- gcc/doc/tm.texi | 8 ++++++++ gcc/doc/tm.texi.in | 2 ++ gcc/function.cc | 15 +++++++++++++-- gcc/target.def | 9 +++++++++ 8 files changed, 43 insertions(+), 18 deletions(-) diff --git a/gcc/calls.cc b/gcc/calls.cc index 4d0bc45be..c1db66883 100644 --- a/gcc/calls.cc +++ b/gcc/calls.cc @@ -2461,7 +2461,8 @@ can_implement_as_sibling_call_p (tree exp, tree addr, const args_size &args_size) { - if (!targetm.have_sibcall_epilogue ()) + if (!targetm.have_sibcall_epilogue () + && !targetm.emit_epilogue_for_sibcall) { maybe_complain_about_tail_call (exp, diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h index 86e444a60..97984f3ab 100644 --- a/gcc/config/aarch64/aarch64-protos.h +++ b/gcc/config/aarch64/aarch64-protos.h @@ -887,7 +887,7 @@ const char * aarch64_gen_far_branch (rtx *, int, const char *, const char *); const char * aarch64_output_probe_stack_range (rtx, rtx); const char * aarch64_output_probe_sve_stack_clash (rtx, rtx, rtx, rtx); void aarch64_err_no_fpadvsimd (machine_mode); -void aarch64_expand_epilogue (bool); +void aarch64_expand_epilogue (rtx_call_insn *); rtx aarch64_ptrue_all (unsigned int); opt_machine_mode aarch64_ptrue_all_mode (rtx); rtx aarch64_convert_sve_data_to_pred (rtx, machine_mode, rtx); diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc index fc7540023..76bb0a5dd 100644 --- a/gcc/config/aarch64/aarch64.cc +++ b/gcc/config/aarch64/aarch64.cc @@ -9829,7 +9829,7 @@ aarch64_use_return_insn_p (void) from a deallocated stack, and we optimize the unwind records by emitting them all together if possible. */ void -aarch64_expand_epilogue (bool for_sibcall) +aarch64_expand_epilogue (rtx_call_insn *sibcall) { poly_int64 initial_adjust = cfun->machine->frame.initial_adjust; HOST_WIDE_INT callee_adjust = cfun->machine->frame.callee_adjust; @@ -9977,7 +9977,7 @@ aarch64_expand_epilogue (bool for_sibcall) explicitly authenticate. */ if (aarch64_return_address_signing_enabled () - && (for_sibcall || !TARGET_ARMV8_3)) + && (sibcall || !TARGET_ARMV8_3)) { switch (aarch64_ra_sign_key) { @@ -9995,7 +9995,7 @@ aarch64_expand_epilogue (bool for_sibcall) } /* Stack adjustment for exception handler. */ - if (crtl->calls_eh_return && !for_sibcall) + if (crtl->calls_eh_return && !sibcall) { /* We need to unwind the stack by the offset computed by EH_RETURN_STACKADJ_RTX. We have already reset the CFA @@ -10006,7 +10006,7 @@ aarch64_expand_epilogue (bool for_sibcall) } emit_use (gen_rtx_REG (DImode, LR_REGNUM)); - if (!for_sibcall) + if (!sibcall) emit_jump_insn (ret_rtx); } @@ -27923,6 +27923,9 @@ aarch64_libgcc_floating_mode_supported_p #undef TARGET_HAVE_SHADOW_CALL_STACK #define TARGET_HAVE_SHADOW_CALL_STACK true +#undef TARGET_EMIT_EPILOGUE_FOR_SIBCALL +#define TARGET_EMIT_EPILOGUE_FOR_SIBCALL aarch64_expand_epilogue + struct gcc_target targetm = TARGET_INITIALIZER; #include "gt-aarch64.h" diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md index 5473e2720..22c22b1c6 100644 --- a/gcc/config/aarch64/aarch64.md +++ b/gcc/config/aarch64/aarch64.md @@ -869,16 +869,7 @@ [(clobber (const_int 0))] "" " - aarch64_expand_epilogue (false); - DONE; - " -) - -(define_expand "sibcall_epilogue" - [(clobber (const_int 0))] - "" - " - aarch64_expand_epilogue (true); + aarch64_expand_epilogue (nullptr); DONE; " ) diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index f8109834d..3601994c3 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -11913,6 +11913,14 @@ the hook might return true if the prologue and epilogue need to switch between instruction sets. @end deftypefn +@deftypefn {Target Hook} void TARGET_EMIT_EPILOGUE_FOR_SIBCALL (rtx_call_insn *@var{call}) +If defined, this hook emits an epilogue sequence for sibling (tail) +call instruction @var{call}. Another way of providing epilogues +for sibling calls is to define the @code{sibcall_epilogue} instruction +pattern; the main advantage of this hook over the pattern is that it +has access to the call instruction. +@end deftypefn + @deftypefn {Target Hook} void TARGET_MACHINE_DEPENDENT_REORG (void) If non-null, this hook performs a target-specific pass over the instruction stream. The compiler will run it at all optimization levels, diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in index 9d72fe18d..8062ee79c 100644 --- a/gcc/doc/tm.texi.in +++ b/gcc/doc/tm.texi.in @@ -7920,6 +7920,8 @@ to by @var{ce_info}. @hook TARGET_USE_LATE_PROLOGUE_EPILOGUE +@hook TARGET_EMIT_EPILOGUE_FOR_SIBCALL + @hook TARGET_MACHINE_DEPENDENT_REORG @hook TARGET_INIT_BUILTINS diff --git a/gcc/function.cc b/gcc/function.cc index eac179dd3..94afb266e 100644 --- a/gcc/function.cc +++ b/gcc/function.cc @@ -6217,7 +6217,17 @@ thread_prologue_and_epilogue_insns (void) if (!(CALL_P (insn) && SIBLING_CALL_P (insn))) continue; - if (rtx_insn *ep_seq = targetm.gen_sibcall_epilogue ()) + rtx_insn *ep_seq; + if (targetm.emit_epilogue_for_sibcall) + { + start_sequence (); + targetm.emit_epilogue_for_sibcall (as_a (insn)); + ep_seq = get_insns (); + end_sequence (); + } + else + ep_seq = targetm.gen_sibcall_epilogue (); + if (ep_seq) { start_sequence (); emit_note (NOTE_INSN_EPILOGUE_BEG); @@ -6267,7 +6277,8 @@ reposition_prologue_and_epilogue_notes (void) { if (!targetm.have_prologue () && !targetm.have_epilogue () - && !targetm.have_sibcall_epilogue ()) + && !targetm.have_sibcall_epilogue () + && !targetm.emit_epilogue_for_sibcall) return; /* Since the hash table is created on demand, the fact that it is diff --git a/gcc/target.def b/gcc/target.def index d70363da5..609b2dff6 100644 --- a/gcc/target.def +++ b/gcc/target.def @@ -4084,6 +4084,15 @@ between instruction sets.", bool, (), hook_bool_void_false) +DEFHOOK +(emit_epilogue_for_sibcall, + "If defined, this hook emits an epilogue sequence for sibling (tail)\n\ +call instruction @var{call}. Another way of providing epilogues\n\ +for sibling calls is to define the @code{sibcall_epilogue} instruction\n\ +pattern; the main advantage of this hook over the pattern is that it\n\ +has access to the call instruction.", + void, (rtx_call_insn *call), NULL) + /* Do machine-dependent code transformations. Called just before delayed-branch scheduling. */ DEFHOOK -- 2.19.1