On Fri, Nov 17, 2023 at 3:26 PM Hongyu Wang <hongyu.w...@intel.com> wrote:
>
> Intel APX PPX feature has been released in [1].
>
> PPX stands for Push-Pop Acceleration. PUSH/PUSH2 and its corresponding POP
> can be marked with a 1-bit hint to indicate that the POP reads the
> value written by the PUSH from the stack. The processor tracks these marked
> instructions internally and fast-forwards register data between
> matching PUSH and POP instructions, without going through memory or
> through the training loop of the Fast Store Forwarding Predictor (FSFP).
> This feature can also be adopted to PUSH2/POP2.
>
> For GCC, we emit explicit suffix 'p' (paired) to indicate the push/pop
> pair are marked with PPX hint. To separate form original push/pop, we
> use UNSPEC to restrict the PPX related patterns. So for pushp/popp, the
> cfi is manually adjusted for the UNSPEC PPX insns.
>
> In the first implementation we only emit them under prologue/epilogue
> when saving/restoring callee-saved registers to make sure push/pop are
> paired. So an extra flag was added to check if PPX insns can be emitted
> for those register save/restore interfaces.
>
> The PPX hint is purely a performance hint. If the 'p' suffix is not
> emitted for paired push/pop, the PPX optimization will be disabled,
> while program sematic will not be affected at all.
>
> Bootstrapped/regtest on x86-64-pc-linux-gnu{-m32,}.
>
> Ok for master?
>
> [1].https://www.intel.com/content/www/us/en/developer/articles/technical/advanced-performance-extensions-apx.ht
>
> gcc/ChangeLog:
>
> * config/i386/i386-opts.h (enum apx_features): Add apx_ppx, add
> it to apx_all.
> * config/i386/i386.cc (ix86_emit_restore_reg_using_pop): Add
> ppx_p parameter for function declaration.
> (gen_push2): Add ppx_p parameter, emit push2p if ppx_p is true.
> (ix86_emit_restore_reg_using_pop2): Likewise for pop2p.
> (gen_pushp): New function to emit pushp and adjust cfi.
> (ix86_emit_save_regs): Emit pushp/push2p under TARGET_APX_PPX.
> (ix86_emit_restore_reg_using_pop): Add ppx_p, emit popp insn
> and adjust cfi when ppx_p is ture.
> (ix86_emit_restore_reg_using_pop2): Add ppx_p and parse to its
> callee.
> (ix86_emit_restore_regs_using_pop2): Likewise.
> (ix86_expand_epilogue): Parse TARGET_APX_PPX to
> ix86_emit_restore_reg_using_pop.
> * config/i386/i386.h (TARGET_APX_PPX): New.
> * config/i386/i386.md (UNSPEC_APXPUSHP): New unspec.
> (UNSPEC_APXPOPP): Likewise.
> (UNSPEC_APXPUSH2P): Likewise.
> (UNSPEC_APXPOP2P_LOW): Likewise.
> (UNSPEC_APXPOP2P_HIGH): Likewise.
> (pushp_di): New define_insn.
> (popp_di): Likewise.
> (push2p_di): Likewise.
> (pop2p_di): Likewise.
> * config/i386/i386.opt: Add apx_ppx enum.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/apx-interrupt-1.c: Adjust option to restrict them
> under certain subfeatures.
> * gcc.target/i386/apx-push2pop2-1.c: Likewise.
> * gcc.target/i386/apx-push2pop2_force_drap-1.c: Likewise.
> * gcc.target/i386/apx-push2pop2_interrupt-1.c: Likewise.
> * gcc.target/i386/apx-ppx-1.c: New test.
> ---
> gcc/config/i386/i386-opts.h | 3 +-
> gcc/config/i386/i386.cc | 113 ++++++++++++++----
> gcc/config/i386/i386.h | 1 +
> gcc/config/i386/i386.md | 47 +++++++-
> gcc/config/i386/i386.opt | 3 +
> .../gcc.target/i386/apx-interrupt-1.c | 2 +-
> gcc/testsuite/gcc.target/i386/apx-ppx-1.c | 9 ++
> .../gcc.target/i386/apx-push2pop2-1.c | 2 +-
> .../i386/apx-push2pop2_force_drap-1.c | 2 +-
> .../i386/apx-push2pop2_interrupt-1.c | 2 +-
> 10 files changed, 158 insertions(+), 26 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/apx-ppx-1.c
>
> diff --git a/gcc/config/i386/i386-opts.h b/gcc/config/i386/i386-opts.h
> index 2ec76a16bce..4d293edb399 100644
> --- a/gcc/config/i386/i386-opts.h
> +++ b/gcc/config/i386/i386-opts.h
> @@ -139,7 +139,8 @@ enum apx_features {
> apx_egpr = 1 << 0,
> apx_push2pop2 = 1 << 1,
> apx_ndd = 1 << 2,
> - apx_all = apx_egpr | apx_push2pop2 | apx_ndd,
> + apx_ppx = 1 << 3,
> + apx_all = apx_egpr | apx_push2pop2 | apx_ndd | apx_ppx,
> };
>
> #endif
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index 683ac643bc8..df2fc236c0a 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -105,7 +105,7 @@ along with GCC; see the file COPYING3. If not see
> static rtx legitimize_dllimport_symbol (rtx, bool);
> static rtx legitimize_pe_coff_extern_decl (rtx, bool);
> static void ix86_print_operand_address_as (FILE *, rtx, addr_space_t, bool);
> -static void ix86_emit_restore_reg_using_pop (rtx);
> +static void ix86_emit_restore_reg_using_pop (rtx, bool = false);
>
>
> #ifndef CHECK_STACK_LIMIT
> @@ -6512,7 +6512,7 @@ gen_popfl (void)
>
> /* Generate a "push2" pattern for input ARG. */
> rtx
> -gen_push2 (rtx mem, rtx reg1, rtx reg2)
> +gen_push2 (rtx mem, rtx reg1, rtx reg2, bool ppx_p = false)
> {
> struct machine_function *m = cfun->machine;
> const int offset = UNITS_PER_WORD * 2;
> @@ -6527,9 +6527,49 @@ gen_push2 (rtx mem, rtx reg1, rtx reg2)
> if (REG_P (reg2) && GET_MODE (reg2) != word_mode)
> reg2 = gen_rtx_REG (word_mode, REGNO (reg2));
>
> - return gen_push2_di (mem, reg1, reg2);
> + return ppx_p ? gen_push2p_di (mem, reg1, reg2):
> + gen_push2_di (mem, reg1, reg2);
> }
>
> +/* Generate a "pushp" insn for input ARG, and set reg notes. */
> +rtx_insn *
> +gen_pushp (rtx arg)
> +{
Can we just overload gen_push with an new arg bool ppx just like we
did for push2/pop2.
> + struct machine_function *m = cfun->machine;
> +
> + if (m->fs.cfa_reg == stack_pointer_rtx)
> + m->fs.cfa_offset += UNITS_PER_WORD;
> + m->fs.sp_offset += UNITS_PER_WORD;
> +
> + if (REG_P (arg) && GET_MODE (arg) != word_mode)
> + arg = gen_rtx_REG (word_mode, REGNO (arg));
> +
> + rtx pat = gen_rtx_MEM (word_mode,
> + gen_rtx_PRE_DEC (Pmode,
> + stack_pointer_rtx));
> + rtx_insn *insn = emit_insn (gen_pushp_di (pat, arg));
> +
Why do we need ..
> + rtx dwarf = gen_rtx_SEQUENCE (VOIDmode, rtvec_alloc (2));
> +
> + rtx dwarf_reg = gen_rtx_REG (word_mode,
> + REGNO (arg));
> + rtx tmp = gen_rtx_SET (gen_frame_mem (DImode,
> + stack_pointer_rtx),
> + dwarf_reg);
> + RTX_FRAME_RELATED_P (tmp) = 1;
> + XVECEXP (dwarf, 0, 1) = tmp;
> + rtx sp_tmp = gen_rtx_SET (stack_pointer_rtx,
> + plus_constant (Pmode,
> + stack_pointer_rtx,
> + -UNITS_PER_WORD));
> + RTX_FRAME_RELATED_P (sp_tmp) = 1;
> + XVECEXP (dwarf, 0, 0) = sp_tmp;
> + add_reg_note (insn, REG_FRAME_RELATED_EXPR, dwarf);
this. I assume pushp should be different from push only by ppx hint, not dwarf.
> +
> + return insn;
> +}
> +
> +
> /* Return >= 0 if there is an unused call-clobbered register available
> for the entire function. */
>
> @@ -7369,7 +7409,10 @@ ix86_emit_save_regs (void)
> for (regno = FIRST_PSEUDO_REGISTER - 1; regno >= 0; regno--)
> if (GENERAL_REGNO_P (regno) && ix86_save_reg (regno, true, true))
> {
> - insn = emit_insn (gen_push (gen_rtx_REG (word_mode, regno)));
> + if (TARGET_APX_PPX)
> + insn = gen_pushp (gen_rtx_REG (word_mode, regno));
> + else
> + insn = emit_insn (gen_push (gen_rtx_REG (word_mode, regno)));
> RTX_FRAME_RELATED_P (insn) = 1;
> }
> }
> @@ -7399,7 +7442,8 @@ ix86_emit_save_regs (void)
> gen_rtx_REG (word_mode,
> regno_list[0]),
> gen_rtx_REG (word_mode,
> -
> regno_list[1])));
> + regno_list[1]),
> + TARGET_APX_PPX));
> RTX_FRAME_RELATED_P (insn) = 1;
> rtx dwarf = gen_rtx_SEQUENCE (VOIDmode, rtvec_alloc (3));
>
> @@ -7431,15 +7475,21 @@ ix86_emit_save_regs (void)
> }
> else
> {
> - insn = emit_insn (gen_push (gen_rtx_REG (word_mode, regno)));
> + if (TARGET_APX_PPX)
> + insn = gen_pushp (gen_rtx_REG (word_mode, regno));
> + else
> + insn = emit_insn (gen_push (gen_rtx_REG (word_mode,
> regno)));
> RTX_FRAME_RELATED_P (insn) = 1;
> aligned = true;
> }
> }
> if (loaded_regnum == 1)
> {
> - insn = emit_insn (gen_push (gen_rtx_REG (word_mode,
> - regno_list[0])));
> + if (TARGET_APX_PPX)
> + insn = gen_pushp (gen_rtx_REG (word_mode, regno_list[0]));
> + else
> + insn = emit_insn (gen_push (gen_rtx_REG (word_mode,
> + regno_list[0])));
> RTX_FRAME_RELATED_P (insn) = 1;
> }
> }
> @@ -9268,15 +9318,30 @@ ix86_expand_prologue (void)
> emit_insn (gen_prologue_use (stack_pointer_rtx));
> }
>
> -/* Emit code to restore REG using a POP insn. */
> +/* Emit code to restore REG using a POP or POPP insn. */
>
> static void
> -ix86_emit_restore_reg_using_pop (rtx reg)
> +ix86_emit_restore_reg_using_pop (rtx reg, bool ppx_p)
> {
> struct machine_function *m = cfun->machine;
> - rtx_insn *insn = emit_insn (gen_pop (reg));
> + rtx_insn *insn;
>
> - ix86_add_cfa_restore_note (insn, reg, m->fs.sp_offset);
> + if (ppx_p)
> + {
> + rtx stack = gen_rtx_MEM (word_mode,
> + gen_rtx_POST_INC (Pmode,
> + stack_pointer_rtx));
> + insn = emit_insn (gen_popp_di (reg, stack));
Diddo for ..
> + RTX_FRAME_RELATED_P (insn) = 1;
> + rtx dwarf = NULL_RTX;
> + dwarf = alloc_reg_note (REG_CFA_RESTORE, reg, dwarf);
> + REG_NOTES (insn) = dwarf;
.. this, why it's different from pop regarding cfa?
> + }
> + else
> + {
> + insn = emit_insn (gen_pop (reg));
> + ix86_add_cfa_restore_note (insn, reg, m->fs.sp_offset);
> + }
> m->fs.sp_offset -= UNITS_PER_WORD;
>
> if (m->fs.cfa_reg == crtl->drap_reg
> @@ -9328,14 +9393,19 @@ ix86_emit_restore_reg_using_pop (rtx reg)
>
> /* Emit code to restore REG using a POP2 insn. */
> static void
> -ix86_emit_restore_reg_using_pop2 (rtx reg1, rtx reg2)
> +ix86_emit_restore_reg_using_pop2 (rtx reg1, rtx reg2, bool ppx_p = false)
> {
> struct machine_function *m = cfun->machine;
> const int offset = UNITS_PER_WORD * 2;
> + rtx_insn *insn;
>
> rtx mem = gen_rtx_MEM (TImode, gen_rtx_POST_INC (Pmode,
> stack_pointer_rtx));
> - rtx_insn *insn = emit_insn (gen_pop2_di (reg1, mem, reg2));
> +
> + if (ppx_p)
> + insn = emit_insn (gen_pop2p_di (reg1, mem, reg2));
> + else
> + insn = emit_insn (gen_pop2_di (reg1, mem, reg2));
>
> RTX_FRAME_RELATED_P (insn) = 1;
>
> @@ -9397,13 +9467,13 @@ ix86_emit_restore_reg_using_pop2 (rtx reg1, rtx reg2)
> /* Emit code to restore saved registers using POP insns. */
>
> static void
> -ix86_emit_restore_regs_using_pop (void)
> +ix86_emit_restore_regs_using_pop (bool ppx_p)
> {
> unsigned int regno;
>
> for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
> if (GENERAL_REGNO_P (regno) && ix86_save_reg (regno, false, true))
> - ix86_emit_restore_reg_using_pop (gen_rtx_REG (word_mode, regno));
> + ix86_emit_restore_reg_using_pop (gen_rtx_REG (word_mode, regno),
> ppx_p);
> }
>
> /* Emit code to restore saved registers using POP2 insns. */
> @@ -9432,20 +9502,23 @@ ix86_emit_restore_regs_using_pop2 (void)
> ix86_emit_restore_reg_using_pop2 (gen_rtx_REG (word_mode,
> regno_list[0]),
> gen_rtx_REG (word_mode,
> -
> regno_list[1]));
> + regno_list[1]),
> + TARGET_APX_PPX);
> loaded_regnum = 0;
> regno_list[0] = regno_list[1] = -1;
> }
> }
> else
> {
> - ix86_emit_restore_reg_using_pop (gen_rtx_REG (word_mode, regno));
> + ix86_emit_restore_reg_using_pop (gen_rtx_REG (word_mode, regno),
> + TARGET_APX_PPX);
> aligned = true;
> }
> }
>
> if (loaded_regnum == 1)
> - ix86_emit_restore_reg_using_pop (gen_rtx_REG (word_mode, regno_list[0]));
> + ix86_emit_restore_reg_using_pop (gen_rtx_REG (word_mode, regno_list[0]),
> + TARGET_APX_PPX);
> }
>
> /* Emit code and notes for the LEAVE instruction. If insn is non-null,
> @@ -9990,7 +10063,7 @@ ix86_expand_epilogue (int style)
> if (TARGET_APX_PUSH2POP2 && m->func_type == TYPE_NORMAL)
> ix86_emit_restore_regs_using_pop2 ();
> else
> - ix86_emit_restore_regs_using_pop ();
> + ix86_emit_restore_regs_using_pop (TARGET_APX_PPX);
> }
>
> /* If we used a stack pointer and haven't already got rid of it,
> diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
> index 037074758ea..227217a8712 100644
> --- a/gcc/config/i386/i386.h
> +++ b/gcc/config/i386/i386.h
> @@ -54,6 +54,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.
> If not, see
> #define TARGET_APX_EGPR (ix86_apx_features & apx_egpr)
> #define TARGET_APX_PUSH2POP2 (ix86_apx_features & apx_push2pop2)
> #define TARGET_APX_NDD (ix86_apx_features & apx_ndd)
> +#define TARGET_APX_PPX (ix86_apx_features & apx_ppx)
>
> #include "config/vxworks-dummy.h"
>
> diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
> index 1b5a794b9e5..8cce4c11e35 100644
> --- a/gcc/config/i386/i386.md
> +++ b/gcc/config/i386/i386.md
> @@ -210,10 +210,17 @@ (define_c_enum "unspec" [
> ;; For insn_callee_abi:
> UNSPEC_CALLEE_ABI
>
> - ;; For PUSH2/POP2 support
> + ;; For APX PUSH2/POP2 support
> UNSPEC_APXPUSH2
> UNSPEC_APXPOP2_LOW
> UNSPEC_APXPOP2_HIGH
> +
> + ;; For APX PPX support
> + UNSPEC_APXPUSHP
> + UNSPEC_APXPOPP
> + UNSPEC_APXPUSH2P
> + UNSPEC_APXPOP2P_LOW
> + UNSPEC_APXPOP2P_HIGH
> ])
>
> (define_c_enum "unspecv" [
> @@ -3785,6 +3792,44 @@ (define_insn "pop2_di"
> [(set_attr "mode" "TI")
> (set_attr "prefix" "evex")])
>
> +(define_insn "pushp_di"
> + [(set (match_operand:DI 0 "push_operand" "=<")
> + (unspec: DI [(match_operand:DI 1 "register_operand" "r")]
> + UNSPEC_APXPUSHP))]
> + "TARGET_64BIT"
> + "pushp\t%1"
> + [(set_attr "mode" "DI")])
I think you just need to add an extra (unspec [(const_int 0)]
UNSPEC_PPX) to origin push_di pattern, then no need for particular
handling of dwarf and cfa stuffs.
Ditto for popp and push2p and pop2p.
> +
> +(define_insn "popp_di"
> + [(set (match_operand:DI 0 "nonimmediate_operand" "=r")
> + (unspec:DI [(match_operand:DI 1 "pop_operand" ">")]
> + UNSPEC_APXPOPP))]
> + "TARGET_APX_PPX"
> + "popp\t%0"
> + [(set_attr "mode" "DI")])
> +
> +(define_insn "push2p_di"
> + [(set (match_operand:TI 0 "push_operand" "=<")
> + (unspec:TI [(match_operand:DI 1 "register_operand" "r")
> + (match_operand:DI 2 "register_operand" "r")]
> + UNSPEC_APXPUSH2P))]
> + "TARGET_APX_PUSH2POP2 && TARGET_APX_PPX"
> + "push2p\t%1, %2"
> + [(set_attr "mode" "TI")
> + (set_attr "type" "multi")
> + (set_attr "prefix" "evex")])
> +
> +(define_insn "pop2p_di"
> + [(parallel [(set (match_operand:DI 0 "register_operand" "=r")
> + (unspec:DI [(match_operand:TI 1 "pop_operand" ">")]
> + UNSPEC_APXPOP2P_LOW))
> + (set (match_operand:DI 2 "register_operand" "=r")
> + (unspec:DI [(const_int 0)] UNSPEC_APXPOP2P_HIGH))])]
> + "TARGET_APX_PUSH2POP2 && TARGET_APX_PPX"
> + "pop2p\t%0, %2"
> + [(set_attr "mode" "TI")
> + (set_attr "prefix" "evex")])
> +
> (define_insn "*pushsf_rex64"
> [(set (match_operand:SF 0 "push_operand" "=X,X,X")
> (match_operand:SF 1 "nonmemory_no_elim_operand" "f,rF,v"))]
> diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
> index 0c3b8f4b621..ee8898e3abb 100644
> --- a/gcc/config/i386/i386.opt
> +++ b/gcc/config/i386/i386.opt
> @@ -1333,6 +1333,9 @@ Enum(apx_features) String(push2pop2)
> Value(apx_push2pop2) Set(3)
> EnumValue
> Enum(apx_features) String(ndd) Value(apx_ndd) Set(4)
>
> +EnumValue
> +Enum(apx_features) String(ppx) Value(apx_ppx) Set(5)
> +
> EnumValue
> Enum(apx_features) String(all) Value(apx_all) Set(1)
>
> diff --git a/gcc/testsuite/gcc.target/i386/apx-interrupt-1.c
> b/gcc/testsuite/gcc.target/i386/apx-interrupt-1.c
> index 5f732d3e316..ffcb8fce71c 100644
> --- a/gcc/testsuite/gcc.target/i386/apx-interrupt-1.c
> +++ b/gcc/testsuite/gcc.target/i386/apx-interrupt-1.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile { target { ! ia32 } } } */
> -/* { dg-options "-mapxf -m64 -O2 -mgeneral-regs-only -mno-cld -mno-push-args
> -maccumulate-outgoing-args" } */
> +/* { dg-options "-mapx-features=egpr -m64 -O2 -mgeneral-regs-only -mno-cld
> -mno-push-args -maccumulate-outgoing-args" } */
> /* { dg-skip-if "does not emit .cfi_xxx" "*-*-darwin*" } */
>
> extern void foo (void *) __attribute__ ((interrupt));
> diff --git a/gcc/testsuite/gcc.target/i386/apx-ppx-1.c
> b/gcc/testsuite/gcc.target/i386/apx-ppx-1.c
> new file mode 100644
> index 00000000000..e9a595381e3
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/apx-ppx-1.c
> @@ -0,0 +1,9 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mapx-features=egpr,push2pop2,ppx" } */
> +
> +#include "apx-push2pop2-1.c"
> +
> +/* { dg-final { scan-assembler "pushp" } } */
> +/* { dg-final { scan-assembler "popp" } } */
> +/* { dg-final { scan-assembler "push2p" } } */
> +/* { dg-final { scan-assembler "pop2p" } } */
> diff --git a/gcc/testsuite/gcc.target/i386/apx-push2pop2-1.c
> b/gcc/testsuite/gcc.target/i386/apx-push2pop2-1.c
> index 089941d3726..c53112758a5 100644
> --- a/gcc/testsuite/gcc.target/i386/apx-push2pop2-1.c
> +++ b/gcc/testsuite/gcc.target/i386/apx-push2pop2-1.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile { target { ! ia32 } } } */
> -/* { dg-options "-O2 -mapxf" } */
> +/* { dg-options "-O2 -mapx-features=push2pop2" } */
> /* { dg-skip-if "does not emit .cfi_xxx" "*-*-darwin*" } */
>
> extern int bar (int);
> diff --git a/gcc/testsuite/gcc.target/i386/apx-push2pop2_force_drap-1.c
> b/gcc/testsuite/gcc.target/i386/apx-push2pop2_force_drap-1.c
> index 656ca91391a..022113bb1e2 100644
> --- a/gcc/testsuite/gcc.target/i386/apx-push2pop2_force_drap-1.c
> +++ b/gcc/testsuite/gcc.target/i386/apx-push2pop2_force_drap-1.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile { target { ! ia32 } } } */
> -/* { dg-options "-O2 -mapxf -mforce-drap" } */
> +/* { dg-options "-O2 -mapx-features=push2pop2 -mforce-drap" } */
> /* { dg-skip-if "does not emit .cfi_xxx" "*-*-darwin*" } */
>
> #include "apx-push2pop2-1.c"
> diff --git a/gcc/testsuite/gcc.target/i386/apx-push2pop2_interrupt-1.c
> b/gcc/testsuite/gcc.target/i386/apx-push2pop2_interrupt-1.c
> index 747f7aaf191..a5b46893208 100644
> --- a/gcc/testsuite/gcc.target/i386/apx-push2pop2_interrupt-1.c
> +++ b/gcc/testsuite/gcc.target/i386/apx-push2pop2_interrupt-1.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile { target { ! ia32 } } } */
> -/* { dg-options "-O2 -mapxf -mgeneral-regs-only -mno-cld -mno-push-args
> -maccumulate-outgoing-args" } */
> +/* { dg-options "-O2 -mapx-features=egpr,push2pop2 -mgeneral-regs-only
> -mno-cld -mno-push-args -maccumulate-outgoing-args" } */
>
> extern void foo (void *) __attribute__ ((interrupt));
>
> --
> 2.31.1
>
--
BR,
Hongtao
