From e86c9ece7ae922fe80017ba2ffe22f6267531682 Mon Sep 17 00:00:00 2001
From: Xi Ruoyao <xry111@xry111.site>
Date: Sun, 23 Apr 2023 20:52:22 +0800
Subject: [PATCH 045/124] LoongArch: Enable shrink wrapping

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.

Signed-off-by: Peng Fan <fanpeng@loongson.cn>
Signed-off-by: ticat_fp <fanpeng@loongson.cn>
---
 gcc/config/loongarch/loongarch.cc             | 179 +++++++++++++++++-
 gcc/config/loongarch/loongarch.h              |   2 +
 .../gcc.target/loongarch/shrink-wrap.c        |  19 ++
 3 files changed, 197 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 d3c6f22ad..4c0f393b6 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"
@@ -1014,19 +1015,23 @@ 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);
       }
 }
@@ -6630,6 +6635,151 @@ 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"
@@ -6827,6 +6977,29 @@ 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 af24bfa01..44ebadfaa 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 000000000..1431536c5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/shrink-wrap.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fshrink-wrap" } */
+
+/* We should not save anything before checking the value of x.  */
+/* { dg-final { scan-assembler-not "st(ptr)?\\\.\[dw\].*b(eq|ne)z" } } */
+
+int
+foo (int x)
+{
+  __asm__ ("nop" :);
+  if (x)
+    {
+      __asm__ ("" ::: "s0", "s1");
+      return x;
+    }
+
+  __asm__ ("" ::: "s2", "s3");
+  return 0;
+}
-- 
2.33.0