diff mbox series

[v2] x86: Generate REG_CFA_UNDEFINED for unsaved callee-saved registers

Message ID 20240129200051.573324-1-hjl.tools@gmail.com
State New
Headers show
Series [v2] x86: Generate REG_CFA_UNDEFINED for unsaved callee-saved registers | expand

Commit Message

H.J. Lu Jan. 29, 2024, 8 p.m. UTC 
Changes in v2:

1. Add REG_CFA_UNDEFINED notes to a frame-related instruction in prologue.
2. Add comments for add_cfi_undefined.

---
Attach REG_CFA_UNDEFINED notes for unsaved callee-saved registers which
have been used in the function to a frame-related instruction in prologue.

gcc/

	PR target/38534
	* dwarf2cfi.cc (add_cfi_undefined): New.
	(dwarf2out_frame_debug_cfa_undefined): Likewise.
	(dwarf2out_frame_debug): Handle REG_CFA_UNDEFINED.
	* reg-notes.def (REG_CFA_UNDEFINED): New.
	* config/i386/i386.cc (ix86_expand_prologue): Attach
	REG_CFA_UNDEFINED notes for unsaved callee-saved registers
	which have been used in the function to a frame-related
	instruction in prologue.

gcc/testsuite/

	PR target/38534
	* gcc.target/i386/no-callee-saved-19.c: New test.
	* gcc.target/i386/no-callee-saved-20.c: Likewise.
	* gcc.target/i386/pr38534-7.c: Likewise.
	* gcc.target/i386/pr38534-8.c: Likewise.
---
 gcc/config/i386/i386.cc                       | 29 ++++++++++
 gcc/dwarf2cfi.cc                              | 58 +++++++++++++++++++
 gcc/reg-notes.def                             |  4 ++
 .../gcc.target/i386/no-callee-saved-19.c      | 17 ++++++
 .../gcc.target/i386/no-callee-saved-20.c      | 12 ++++
 gcc/testsuite/gcc.target/i386/pr38534-7.c     | 18 ++++++
 gcc/testsuite/gcc.target/i386/pr38534-8.c     | 13 +++++
 7 files changed, 151 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/i386/no-callee-saved-19.c
 create mode 100644 gcc/testsuite/gcc.target/i386/no-callee-saved-20.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr38534-7.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr38534-8.c
diff mbox series

Patch

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index b3e7c74846e..4b7026f3ab4 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -9304,6 +9304,35 @@  ix86_expand_prologue (void)
      combined with prologue modifications.  */
   if (TARGET_SEH)
     emit_insn (gen_prologue_use (stack_pointer_rtx));
+
+  if (cfun->machine->call_saved_registers
+      != TYPE_NO_CALLEE_SAVED_REGISTERS)
+    return;
+
+  /* Attach REG_CFA_UNDEFINED notes for unsaved callee-saved registers
+     which have been used in the function to a frame-related instruction
+     in prologue.  */
+
+  insn = nullptr;
+  rtx_insn *next;
+  for (next = get_insns (); next; next = NEXT_INSN (next))
+    {
+      if (!RTX_FRAME_RELATED_P (next))
+	continue;
+      insn = next;
+    }
+
+  if (!insn)
+    return;
+
+  for (int i = 0; i < FIRST_PSEUDO_REGISTER; i++)
+    if (df_regs_ever_live_p (i)
+	&& !fixed_regs[i]
+	&& !call_used_regs[i]
+	&& !STACK_REGNO_P (i)
+	&& !MMX_REGNO_P (i))
+      add_reg_note (insn, REG_CFA_UNDEFINED,
+		    gen_rtx_REG (word_mode, i));
 }
 
 /* Emit code to restore REG using a POP or POPP insn.  */
diff --git a/gcc/dwarf2cfi.cc b/gcc/dwarf2cfi.cc
index 1231b5bb5f0..9ba0ac07ee7 100644
--- a/gcc/dwarf2cfi.cc
+++ b/gcc/dwarf2cfi.cc
@@ -517,6 +517,20 @@  add_cfi_restore (unsigned reg)
   add_cfi (cfi);
 }
 
+/* Add DW_CFA_undefined either to the current insn stream or to a vector,
+   or both.  */
+
+static void
+add_cfi_undefined (unsigned reg)
+{
+  dw_cfi_ref cfi = new_cfi ();
+
+  cfi->dw_cfi_opc = DW_CFA_undefined;
+  cfi->dw_cfi_oprnd1.dw_cfi_reg_num = reg;
+
+  add_cfi (cfi);
+}
+
 /* Perform ROW->REG_SAVE[COLUMN] = CFI.  CFI may be null, indicating
    that the register column is no longer saved.  */
 
@@ -1532,6 +1546,37 @@  dwarf2out_frame_debug_cfa_restore (rtx reg, bool emit_cfi)
     }
 }
 
+/* A subroutine of dwarf2out_frame_debug, process a REG_CFA_UNDEFINED
+   note.  */
+
+static void
+dwarf2out_frame_debug_cfa_undefined (rtx reg)
+{
+  gcc_assert (REG_P (reg));
+
+  rtx span = targetm.dwarf_register_span (reg);
+  if (!span)
+    {
+      unsigned int regno = dwf_regno (reg);
+      add_cfi_undefined (regno);
+    }
+  else
+    {
+      /* We have a PARALLEL describing where the contents of REG live.
+	 Restore the register for each piece of the PARALLEL.  */
+      gcc_assert (GET_CODE (span) == PARALLEL);
+
+      const int par_len = XVECLEN (span, 0);
+      for (int par_index = 0; par_index < par_len; par_index++)
+	{
+	  reg = XVECEXP (span, 0, par_index);
+	  gcc_assert (REG_P (reg));
+	  unsigned int regno = dwf_regno (reg);
+	  add_cfi_undefined (regno);
+	}
+    }
+}
+
 /* A subroutine of dwarf2out_frame_debug, process a REG_CFA_WINDOW_SAVE.
 
    ??? Perhaps we should note in the CIE where windows are saved (instead
@@ -2326,6 +2371,19 @@  dwarf2out_frame_debug (rtx_insn *insn)
 	handled_one = true;
 	break;
 
+      case REG_CFA_UNDEFINED:
+	n = XEXP (note, 0);
+	if (n == nullptr)
+	  {
+	    n = PATTERN (insn);
+	    if (GET_CODE (n) == PARALLEL)
+	      n = XVECEXP (n, 0, 0);
+	    n = XEXP (n, 0);
+	  }
+	dwarf2out_frame_debug_cfa_undefined (n);
+	handled_one = true;
+	break;
+
       case REG_CFA_SET_VDRAP:
 	n = XEXP (note, 0);
 	if (REG_P (n))
diff --git a/gcc/reg-notes.def b/gcc/reg-notes.def
index 5b878fb2a1c..8a78ebb6864 100644
--- a/gcc/reg-notes.def
+++ b/gcc/reg-notes.def
@@ -152,6 +152,10 @@  REG_CFA_NOTE (CFA_EXPRESSION)
    the given register.  */
 REG_CFA_NOTE (CFA_VAL_EXPRESSION)
 
+/* Attached to insns that are RTX_FRAME_RELATED_P, to specific a register
+   with undefined value.  */
+REG_CFA_NOTE (CFA_UNDEFINED)
+
 /* Attached to insns that are RTX_FRAME_RELATED_P, with the information
    that this is a restore operation, i.e. will result in DW_CFA_restore
    or the like.  Either the attached rtx, or the destination of the insn's
diff --git a/gcc/testsuite/gcc.target/i386/no-callee-saved-19.c b/gcc/testsuite/gcc.target/i386/no-callee-saved-19.c
new file mode 100644
index 00000000000..578a093e0ca
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/no-callee-saved-19.c
@@ -0,0 +1,17 @@ 
+/* { dg-do assemble { target *-*-linux* *-*-gnu* } } */
+/* { dg-options "-save-temps -march=tigerlake -O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move" } */
+
+#include "no-callee-saved-1.c"
+
+/* { dg-final { scan-assembler-not "push" } } */
+/* { dg-final { scan-assembler-not "pop" } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 3" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 6" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 12" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 13" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 14" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 15" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 3" 1 { target ia32 } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 5" 1 { target ia32 } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 6" 1 { target ia32 } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 7" 1 { target ia32 } } } */
diff --git a/gcc/testsuite/gcc.target/i386/no-callee-saved-20.c b/gcc/testsuite/gcc.target/i386/no-callee-saved-20.c
new file mode 100644
index 00000000000..fc94778824a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/no-callee-saved-20.c
@@ -0,0 +1,12 @@ 
+/* { dg-do compile { target cfi } } */
+/* { dg-options "-march=tigerlake -O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move" } */
+
+__attribute__ ((no_callee_saved_registers))
+void
+foo (void)
+{
+}
+
+/* { dg-final { scan-assembler-not "push" } } */
+/* { dg-final { scan-assembler-not "pop" } } */
+/* { dg-final { scan-assembler-not ".cfi_undefined" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr38534-7.c b/gcc/testsuite/gcc.target/i386/pr38534-7.c
new file mode 100644
index 00000000000..4a0d399d904
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr38534-7.c
@@ -0,0 +1,18 @@ 
+/* { dg-do assemble { target *-*-linux* *-*-gnu* } } */
+/* { dg-options "-save-temps -march=tigerlake -O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move" } */
+
+#include "pr38534-1.c"
+
+/* { dg-final { scan-assembler-not "push" } } */
+/* { dg-final { scan-assembler-not "pop" } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 3" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 6" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 12" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 13" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 14" 1 { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 15" 1 { target lp64 } } } */
+/* { dg-final { scan-assembler-not ".cfi_undefined 15" { target x32 } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 3" 1 { target ia32 } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 5" 1 { target ia32 } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 6" 1 { target ia32 } } } */
+/* { dg-final { scan-assembler-times ".cfi_undefined 7" 1 { target ia32 } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr38534-8.c b/gcc/testsuite/gcc.target/i386/pr38534-8.c
new file mode 100644
index 00000000000..020c1512db1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr38534-8.c
@@ -0,0 +1,13 @@ 
+/* { dg-do compile { target cfi } } */
+/* { dg-options "-march=tigerlake -O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move" } */
+
+void
+__attribute__((noreturn))
+no_return_to_caller (void)
+{
+  while (1);
+}
+
+/* { dg-final { scan-assembler-not "push" } } */
+/* { dg-final { scan-assembler-not "pop" } } */
+/* { dg-final { scan-assembler-not ".cfi_undefined" } } */