Re: [PATCH] LoongArch: Enable shrink wrapping

[Lulu Cheng <chenglulu@loongson.cn>]

+guojie

在 2023/4/23 下午9:19, Xi Ruoyao 写道:
> This commit implements the target macros for shrink wrapping of function
> prologues/epilogues shrink wrapping on LoongArch.
>
> Bootstrapped and regtested on loongarch64-linux-gnu.  I don't have an
> access to SPEC CPU so I hope the reviewer can perform a benchmark to see
> if there is real benefit.
>
> gcc/ChangeLog:
>
> 	* config/loongarch/loongarch.h (struct machine_function): Add
> 	reg_is_wrapped_separately array for register wrapping
> 	information.
> 	* config/loongarch/loongarch.cc
> 	(loongarch_get_separate_components): New function.
> 	(loongarch_components_for_bb): Likewise.
> 	(loongarch_disqualify_components): Likewise.
> 	(loongarch_process_components): Likewise.
> 	(loongarch_emit_prologue_components): Likewise.
> 	(loongarch_emit_epilogue_components): Likewise.
> 	(loongarch_set_handled_components): Likewise.
> 	(TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS): Define.
> 	(TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB): Likewise.
> 	(TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS): Likewise.
> 	(TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS): Likewise.
> 	(TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS): Likewise.
> 	(TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS): Likewise.
> 	(loongarch_for_each_saved_reg): Skip registers that are wrapped
> 	separately.
>
> gcc/testsuite/ChangeLog:
>
> 	* gcc.target/loongarch/shrink-wrap.c: New test.
> ---
>   gcc/config/loongarch/loongarch.cc             | 179 +++++++++++++++++-
>   gcc/config/loongarch/loongarch.h              |   2 +
>   .../gcc.target/loongarch/shrink-wrap.c        |  22 +++
>   3 files changed, 200 insertions(+), 3 deletions(-)
>   create mode 100644 gcc/testsuite/gcc.target/loongarch/shrink-wrap.c
>
> diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
> index e523fcb6b7f..d0024237a6a 100644
> --- a/gcc/config/loongarch/loongarch.cc
> +++ b/gcc/config/loongarch/loongarch.cc
> @@ -64,6 +64,7 @@ along with GCC; see the file COPYING3.  If not see
>   #include "builtins.h"
>   #include "rtl-iter.h"
>   #include "opts.h"
> +#include "function-abi.h"
>   
>   /* This file should be included last.  */
>   #include "target-def.h"
> @@ -1017,19 +1018,23 @@ loongarch_for_each_saved_reg (HOST_WIDE_INT sp_offset,
>     for (int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
>       if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
>         {
> -	loongarch_save_restore_reg (word_mode, regno, offset, fn);
> +	if (!cfun->machine->reg_is_wrapped_separately[regno])
> +	  loongarch_save_restore_reg (word_mode, regno, offset, fn);
> +
>   	offset -= UNITS_PER_WORD;
>         }
>   
>     /* This loop must iterate over the same space as its companion in
>        loongarch_compute_frame_info.  */
>     offset = cfun->machine->frame.fp_sp_offset - sp_offset;
> +  machine_mode mode = TARGET_DOUBLE_FLOAT ? DFmode : SFmode;
> +
>     for (int regno = FP_REG_FIRST; regno <= FP_REG_LAST; regno++)
>       if (BITSET_P (cfun->machine->frame.fmask, regno - FP_REG_FIRST))
>         {
> -	machine_mode mode = TARGET_DOUBLE_FLOAT ? DFmode : SFmode;
> +	if (!cfun->machine->reg_is_wrapped_separately[regno])
> +	  loongarch_save_restore_reg (word_mode, regno, offset, fn);
>   
> -	loongarch_save_restore_reg (mode, regno, offset, fn);
>   	offset -= GET_MODE_SIZE (mode);
>         }
>   }
> @@ -6644,6 +6649,151 @@ loongarch_asan_shadow_offset (void)
>     return TARGET_64BIT ? (HOST_WIDE_INT_1 << 46) : 0;
>   }
>   
> +static sbitmap
> +loongarch_get_separate_components (void)
> +{
> +  HOST_WIDE_INT offset;
> +  sbitmap components = sbitmap_alloc (FIRST_PSEUDO_REGISTER);
> +  bitmap_clear (components);
> +  offset = cfun->machine->frame.gp_sp_offset;
> +
> +  /* The stack should be aligned to 16-bytes boundary, so we can make the use
> +     of ldptr instructions.  */
> +  gcc_assert (offset % UNITS_PER_WORD == 0);
> +
> +  for (unsigned int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
> +    if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
> +      {
> +	/* We can wrap general registers saved at [sp, sp + 32768) using the
> +	   ldptr/stptr instructions.  For large offsets a pseudo register
> +	   might be needed which cannot be created during the shrink
> +	   wrapping pass.
> +
> +	   TODO: This may need a revise when we add LA32 as ldptr.w is not
> +	   guaranteed available by the manual.  */
> +	if (offset < 32768)
> +	  bitmap_set_bit (components, regno);
> +
> +	offset -= UNITS_PER_WORD;
> +      }
> +
> +  offset = cfun->machine->frame.fp_sp_offset;
> +  for (unsigned int regno = FP_REG_FIRST; regno <= FP_REG_LAST; regno++)
> +    if (BITSET_P (cfun->machine->frame.fmask, regno - FP_REG_FIRST))
> +      {
> +	/* We can only wrap FP registers with imm12 offsets.  For large
> +	   offsets a pseudo register might be needed which cannot be
> +	   created during the shrink wrapping pass.  */
> +	if (IMM12_OPERAND (offset))
> +	  bitmap_set_bit (components, regno);
> +
> +	offset -= UNITS_PER_FPREG;
> +      }
> +
> +  /* Don't mess with the hard frame pointer.  */
> +  if (frame_pointer_needed)
> +    bitmap_clear_bit (components, HARD_FRAME_POINTER_REGNUM);
> +
> +  bitmap_clear_bit (components, RETURN_ADDR_REGNUM);
> +
> +  return components;
> +}
> +
> +static sbitmap
> +loongarch_components_for_bb (basic_block bb)
> +{
> +  /* Registers are used in a bb if they are in the IN, GEN, or KILL sets.  */
> +  auto_bitmap used;
> +  bitmap_copy (used, DF_LIVE_IN (bb));
> +  bitmap_ior_into (used, &DF_LIVE_BB_INFO (bb)->gen);
> +  bitmap_ior_into (used, &DF_LIVE_BB_INFO (bb)->kill);
> +
> +  sbitmap components = sbitmap_alloc (FIRST_PSEUDO_REGISTER);
> +  bitmap_clear (components);
> +
> +  function_abi_aggregator callee_abis;
> +  rtx_insn *insn;
> +  FOR_BB_INSNS (bb, insn)
> +    if (CALL_P (insn))
> +      callee_abis.note_callee_abi (insn_callee_abi (insn));
> +
> +  HARD_REG_SET extra_caller_saves =
> +    callee_abis.caller_save_regs (*crtl->abi);
> +
> +  for (unsigned int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
> +    if (!fixed_regs[regno]
> +	&& !crtl->abi->clobbers_full_reg_p (regno)
> +	&& (TEST_HARD_REG_BIT (extra_caller_saves, regno) ||
> +	    bitmap_bit_p (used, regno)))
> +      bitmap_set_bit (components, regno);
> +
> +  for (unsigned int regno = FP_REG_FIRST; regno <= FP_REG_LAST; regno++)
> +    if (!fixed_regs[regno]
> +	&& !crtl->abi->clobbers_full_reg_p (regno)
> +	&& (TEST_HARD_REG_BIT (extra_caller_saves, regno) ||
> +	    bitmap_bit_p (used, regno)))
> +      bitmap_set_bit (components, regno);
> +
> +  return components;
> +}
> +
> +static void
> +loongarch_disqualify_components (sbitmap, edge, sbitmap, bool)
> +{
> +  /* Do nothing.  */
> +}
> +
> +static void
> +loongarch_process_components (sbitmap components, loongarch_save_restore_fn fn)
> +{
> +  HOST_WIDE_INT offset = cfun->machine->frame.gp_sp_offset;
> +
> +  for (unsigned int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
> +    if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
> +      {
> +	if (bitmap_bit_p (components, regno))
> +	  loongarch_save_restore_reg (word_mode, regno, offset, fn);
> +
> +	offset -= UNITS_PER_WORD;
> +      }
> +
> +  offset = cfun->machine->frame.fp_sp_offset;
> +  machine_mode mode = TARGET_DOUBLE_FLOAT ? DFmode : SFmode;
> +
> +  for (unsigned int regno = FP_REG_FIRST; regno <= FP_REG_LAST; regno++)
> +    if (BITSET_P (cfun->machine->frame.fmask, regno - FP_REG_FIRST))
> +      {
> +	if (bitmap_bit_p (components, regno))
> +	  loongarch_save_restore_reg (mode, regno, offset, fn);
> +
> +	offset -= UNITS_PER_FPREG;
> +      }
> +}
> +
> +static void
> +loongarch_emit_prologue_components (sbitmap components)
> +{
> +  loongarch_process_components (components, loongarch_save_reg);
> +}
> +
> +static void
> +loongarch_emit_epilogue_components (sbitmap components)
> +{
> +  loongarch_process_components (components, loongarch_restore_reg);
> +}
> +
> +static void
> +loongarch_set_handled_components (sbitmap components)
> +{
> +    for (unsigned int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
> +      if (bitmap_bit_p (components, regno))
> +	cfun->machine->reg_is_wrapped_separately[regno] = true;
> +
> +    for (unsigned int regno = FP_REG_FIRST; regno <= FP_REG_LAST; regno++)
> +      if (bitmap_bit_p (components, regno))
> +	cfun->machine->reg_is_wrapped_separately[regno] = true;
> +}
> +
>   /* Initialize the GCC target structure.  */
>   #undef TARGET_ASM_ALIGNED_HI_OP
>   #define TARGET_ASM_ALIGNED_HI_OP "\t.half\t"
> @@ -6841,6 +6991,29 @@ loongarch_asan_shadow_offset (void)
>   #undef TARGET_ASAN_SHADOW_OFFSET
>   #define TARGET_ASAN_SHADOW_OFFSET loongarch_asan_shadow_offset
>   
> +#undef TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS
> +#define TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS \
> +  loongarch_get_separate_components
> +
> +#undef TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB
> +#define TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB loongarch_components_for_bb
> +
> +#undef TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS
> +#define TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS \
> +  loongarch_disqualify_components
> +
> +#undef TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS
> +#define TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS \
> +  loongarch_emit_prologue_components
> +
> +#undef TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS
> +#define TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS \
> +  loongarch_emit_epilogue_components
> +
> +#undef TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS
> +#define TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS \
> +  loongarch_set_handled_components
> +
>   struct gcc_target targetm = TARGET_INITIALIZER;
>   
>   #include "gt-loongarch.h"
> diff --git a/gcc/config/loongarch/loongarch.h b/gcc/config/loongarch/loongarch.h
> index a9eff6a81bd..829acdaa9be 100644
> --- a/gcc/config/loongarch/loongarch.h
> +++ b/gcc/config/loongarch/loongarch.h
> @@ -1147,6 +1147,8 @@ struct GTY (()) machine_function
>     /* The current frame information, calculated by loongarch_compute_frame_info.
>      */
>     struct loongarch_frame_info frame;
> +
> +  bool reg_is_wrapped_separately[FIRST_PSEUDO_REGISTER];
>   };
>   #endif
>   
> diff --git a/gcc/testsuite/gcc.target/loongarch/shrink-wrap.c b/gcc/testsuite/gcc.target/loongarch/shrink-wrap.c
> new file mode 100644
> index 00000000000..f2c867a2769
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/loongarch/shrink-wrap.c
> @@ -0,0 +1,22 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fshrink-wrap" } */
> +
> +/* f(x) should do nothing if x is 0.  */
> +/* { dg-final { scan-assembler "bnez\t\\\$r4,\[^\n\]*\n\tjr\t\\\$r1" } } */
> +
> +void g(void);
> +
> +void
> +f(int x)
> +{
> +  if (x)
> +    {
> +      register int s0 asm("s0") = x;
> +      register int s1 asm("s1") = x;
> +      register int s2 asm("s2") = x;
> +      asm("" : : "r"(s0));
> +      asm("" : : "r"(s1));
> +      asm("" : : "r"(s2));
> +      g();
> +    }
> +}