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 --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" } } */
--
2.43.0
