On Thu, Feb 14, 2019 at 08:13:32PM -0800, H.J. Lu wrote:
> NOTE_INSN_DELETED_LABEL is used to mark what used to be a 'code_label',
> but was not used for other purposes than taking its address and was
> transformed to mark that no code jumps to it. NOTE_INSN_DELETED_LABEL
> is generated only in 3 places:
>
> 1. When delete_insn sees an unused label which is an explicit label in
> the input source code or its address is taken, it turns the label into
> a NOTE_INSN_DELETED_LABEL note.
> 2. When rtl_tidy_fallthru_edge deletes a tablejump, it turns the
> tablejump into a NOTE_INSN_DELETED_LABEL note.
> 3. ix86_init_large_pic_reg creats a NOTE_INSN_DELETED_LABEL note, .L2,
> to initialize large model PIC register:
>
> L2:
> movabsq $_GLOBAL_OFFSET_TABLE_-.L2, %r11
> leaq .L2(%rip), %rax
> movabsq $val@GOT, %rdx
> addq %r11, %rax
>
> Among of them, ENDBR is needed only when the label address is taken.
> rest_of_insert_endbranch has
>
> if ((LABEL_P (insn) && LABEL_PRESERVE_P (insn))
> || (NOTE_P (insn)
> && NOTE_KIND (insn) == NOTE_INSN_DELETED_LABEL))
> /* TODO. Check /s bit also. */
> {
> cet_eb = gen_nop_endbr ();
> emit_insn_after (cet_eb, insn);
> continue;
> }
>
> For NOTE_INSN_DELETED_LABEL, we should check if forced_labels to see
> if its address is taken. Also ix86_init_large_pic_reg shouldn't set
> LABEL_PRESERVE_P (in_struct) since NOTE_INSN_DELETED_LABEL is suffcient
> to keep the label.
>
> gcc/
>
> PR target/89355
> * config/i386/i386.c (rest_of_insert_endbranch): Check
> forced_labels to see if the address of NOTE_INSN_DELETED_LABEL
> is taken.
> (ix86_init_large_pic_reg): Don't set LABEL_PRESERVE_P.
>
Here is the updated patch. We should check LABEL_PRESERVE_P on
NOTE_INSN_DELETED_LABEL to see if its address is taken.
OK for trunk?
Thanks.
H.J.
---
NOTE_INSN_DELETED_LABEL is used to mark what used to be a 'code_label',
but was not used for other purposes than taking its address and was
transformed to mark that no code jumps to it. Since LABEL_PRESERVE_P is
true only if the label address was taken, check LABEL_PRESERVE_P before
inserting ENDBR.
2019-02-15 H.J. Lu <hongjiu...@intel.com>
Hongtao Liu <hongtao....@intel.com>
gcc/
PR target/89355
* config/i386/i386.c (rest_of_insert_endbranch): LABEL_PRESERVE_P
to see if the address of NOTE_INSN_DELETED_LABEL is taken.
(ix86_init_large_pic_reg): Don't set LABEL_PRESERVE_P.
gcc/testsuite/
PR target/89355
* gcc.target/i386/cet-label-3.c: New test.
* gcc.target/i386/cet-label-4.c: Likewise.
* gcc.target/i386/cet-label-5.c: Likewise.
---
gcc/config/i386/i386.c | 9 ++++----
gcc/testsuite/gcc.target/i386/cet-label-3.c | 23 +++++++++++++++++++++
gcc/testsuite/gcc.target/i386/cet-label-4.c | 12 +++++++++++
gcc/testsuite/gcc.target/i386/cet-label-5.c | 13 ++++++++++++
4 files changed, 52 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/cet-label-3.c
create mode 100644 gcc/testsuite/gcc.target/i386/cet-label-4.c
create mode 100644 gcc/testsuite/gcc.target/i386/cet-label-5.c
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 609273e4fc4..acdc789b834 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -2734,10 +2734,10 @@ rest_of_insert_endbranch (void)
continue;
}
- if ((LABEL_P (insn) && LABEL_PRESERVE_P (insn))
- || (NOTE_P (insn)
- && NOTE_KIND (insn) == NOTE_INSN_DELETED_LABEL))
- /* TODO. Check /s bit also. */
+ if ((LABEL_P (insn)
+ || (NOTE_P (insn)
+ && NOTE_KIND (insn) == NOTE_INSN_DELETED_LABEL))
+ && LABEL_PRESERVE_P (insn))
{
cet_eb = gen_nop_endbr ();
emit_insn_after (cet_eb, insn);
@@ -6997,7 +6997,6 @@ ix86_init_large_pic_reg (unsigned int tmp_regno)
gcc_assert (Pmode == DImode);
label = gen_label_rtx ();
emit_label (label);
- LABEL_PRESERVE_P (label) = 1;
tmp_reg = gen_rtx_REG (Pmode, tmp_regno);
gcc_assert (REGNO (pic_offset_table_rtx) != tmp_regno);
emit_insn (gen_set_rip_rex64 (pic_offset_table_rtx,
diff --git a/gcc/testsuite/gcc.target/i386/cet-label-3.c
b/gcc/testsuite/gcc.target/i386/cet-label-3.c
new file mode 100644
index 00000000000..9f427a866f3
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/cet-label-3.c
@@ -0,0 +1,23 @@
+/* PR target/89355 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fcf-protection" } */
+/* { dg-final { scan-assembler-times "endbr32" 1 { target ia32 } } } */
+/* { dg-final { scan-assembler-times "endbr64" 1 { target { ! ia32 } } } } */
+int
+test (int* val)
+{
+ int status = 99;
+
+ if (!val)
+ {
+ status = 22;
+ goto end;
+ }
+
+ extern int x;
+ *val = x;
+
+ status = 0;
+end:
+ return status;
+}
diff --git a/gcc/testsuite/gcc.target/i386/cet-label-4.c
b/gcc/testsuite/gcc.target/i386/cet-label-4.c
new file mode 100644
index 00000000000..d743d2bf202
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/cet-label-4.c
@@ -0,0 +1,12 @@
+/* PR target/89355 */
+/* { dg-do compile { target { fpic && lp64 } } } */
+/* { dg-options "-O2 -fcf-protection -fPIC -mcmodel=large" } */
+/* { dg-final { scan-assembler-times "endbr64" 1 } } */
+
+extern int val;
+
+int
+test (void)
+{
+ return val;
+}
diff --git a/gcc/testsuite/gcc.target/i386/cet-label-5.c
b/gcc/testsuite/gcc.target/i386/cet-label-5.c
new file mode 100644
index 00000000000..4d5ca816598
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/cet-label-5.c
@@ -0,0 +1,13 @@
+/* PR target/89355 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fcf-protection -Wno-return-local-addr" } */
+/* { dg-final { scan-assembler-times "endbr32" 2 { target ia32 } } } */
+/* { dg-final { scan-assembler-times "endbr64" 2 { target { ! ia32 } } } } */
+
+void *
+func (void)
+{
+ return &&bar;
+bar:
+ return 0;
+}
--
2.20.1
