i386: Add __x86_indirect_thunk_nt_reg for -fcf-protection -mcet

nocf_check attribute can be used with -fcf-protection -mcet to disable
control-flow check by adding NOTRACK prefix before indirect branch.
When -mindirect-branch=thunk-extern -mindirect-branch-register is added,
indirect branch via register, "notrack call/jmp reg", is converted to

    call/jmp __x86_indirect_thunk_nt_reg

When running on machines with CET enabled, __x86_indirect_thunk_nt_reg
can be updated to

    notrack jmp reg

at run-time to restore NOTRACK prefix in the original indirect branch.

Since we don't support -mindirect-branch=thunk-extern, CET and MPX at
the same time, -mindirect-branch=thunk-extern is disallowed with
-fcf-protection=branch and -fcheck-pointer-bounds.

Tested on i686 and x86-64.

gcc/

	PR target/84176
	* config/i386/i386.c (ix86_set_indirect_branch_type): Issue an
	error when -mindirect-branch=thunk-extern, -fcf-protection=branch
	and -fcheck-pointer-bounds are used together.
	(indirect_thunk_prefix): New enum.
	(indirect_thunk_need_prefix): New function.
	(indirect_thunk_name): Replace need_bnd_p with need_prefix.  Use
	"_nt" instead of "_bnd" for NOTRACK prefix.
	(output_indirect_thunk): Replace need_bnd_p with need_prefix.
	(output_indirect_thunk_function): Likewise.
	(): Likewise.
	(ix86_code_end): Update output_indirect_thunk_function calls.
	(ix86_output_indirect_branch_via_reg): Replace
	ix86_bnd_prefixed_insn_p with indirect_thunk_need_prefix.
	(ix86_output_indirect_branch_via_push): Likewise.
	(ix86_output_function_return): Likewise.
	* doc/invoke.texi: Document -mindirect-branch=thunk-extern is
	incompatible with -fcf-protection=branch and
	-fcheck-pointer-bounds.

gcc/testsuite/

	PR target/84176
	* gcc.target/i386/indirect-thunk-11.c: New test.
	* gcc.target/i386/indirect-thunk-12.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-12.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-13.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-14.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-15.c: Likewise.
	* gcc.target/i386/indirect-thunk-attr-16.c: Likewise.
	* gcc.target/i386/indirect-thunk-extern-10.c: Likewise.
	* gcc.target/i386/indirect-thunk-extern-8.c: Likewise.
	* gcc.target/i386/indirect-thunk-extern-9.c: Likewise.

From-SVN: r257909

gcc/ChangeLog

+2018-02-22  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR target/84176
+	* config/i386/i386.c (ix86_set_indirect_branch_type): Issue an
+	error when -mindirect-branch=thunk-extern, -fcf-protection=branch
+	and -fcheck-pointer-bounds are used together.
+	(indirect_thunk_prefix): New enum.
+	(indirect_thunk_need_prefix): New function.
+	(indirect_thunk_name): Replace need_bnd_p with need_prefix.  Use
+	"_nt" instead of "_bnd" for NOTRACK prefix.
+	(output_indirect_thunk): Replace need_bnd_p with need_prefix.
+	(output_indirect_thunk_function): Likewise.
+	(): Likewise.
+	(ix86_code_end): Update output_indirect_thunk_function calls.
+	(ix86_output_indirect_branch_via_reg): Replace
+	ix86_bnd_prefixed_insn_p with indirect_thunk_need_prefix.
+	(ix86_output_indirect_branch_via_push): Likewise.
+	(ix86_output_function_return): Likewise.
+	* doc/invoke.texi: Document -mindirect-branch=thunk-extern is
+	incompatible with -fcf-protection=branch and
+	-fcheck-pointer-bounds.
+
 2018-02-22  Steve Ellcey  <sellcey@cavium.com>
 
 	PR target/83335

gcc/doc/invoke.texi

@@ -27837,6 +27837,11 @@ Note that @option{-mcmodel=large} is incompatible with
 @option{-mindirect-branch=thunk-extern} since the thunk function may
 not be reachable in large code model.
 
+Note that @option{-mindirect-branch=thunk-extern} is incompatible with
+@option{-fcf-protection=branch} and @option{-fcheck-pointer-bounds}
+since the external thunk can not be modified to disable control-flow
+check.
+
 @item -mfunction-return=@var{choice}
 @opindex -mfunction-return
 Convert function return with @var{choice}.  The default is @samp{keep},

gcc/testsuite/ChangeLog

+2018-02-22  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR target/84176
+	* gcc.target/i386/indirect-thunk-11.c: New test.
+	* gcc.target/i386/indirect-thunk-12.c: Likewise.
+	* gcc.target/i386/indirect-thunk-attr-12.c: Likewise.
+	* gcc.target/i386/indirect-thunk-attr-13.c: Likewise.
+	* gcc.target/i386/indirect-thunk-attr-14.c: Likewise.
+	* gcc.target/i386/indirect-thunk-attr-15.c: Likewise.
+	* gcc.target/i386/indirect-thunk-attr-16.c: Likewise.
+	* gcc.target/i386/indirect-thunk-extern-10.c: Likewise.
+	* gcc.target/i386/indirect-thunk-extern-8.c: Likewise.
+	* gcc.target/i386/indirect-thunk-extern-9.c: Likewise.
+
 2018-02-22  Steve Ellcey  <sellcey@cavium.com>
 
 	PR target/83335

gcc/testsuite/gcc.target/i386/indirect-thunk-11.c

+/* { dg-do compile { target { ! x32 } } } */
+/* { dg-options "-O2 -mindirect-branch=thunk-extern -fcf-protection -mcet -fcheck-pointer-bounds -mmpx" } */
+
+void
+bar (void)
+{ /* { dg-error "'-mindirect-branch=thunk-extern', '-fcf-protection=branch' and '-fcheck-pointer-bounds' are not compatible" } */
+}

gcc/testsuite/gcc.target/i386/indirect-thunk-12.c

+/* { dg-do compile { target { ! x32 } } } */
+/* { dg-options "-O2 -mindirect-branch=thunk -fcf-protection -mcet -fcheck-pointer-bounds -mmpx" } */
+
+void
+bar (void)
+{
+}

gcc/testsuite/gcc.target/i386/indirect-thunk-attr-12.c

+/* { dg-do compile { target { ! x32 } } } */
+/* { dg-options "-O2 -mindirect-branch=keep -fcf-protection -mcet -fcheck-pointer-bounds -mmpx" } */
+
+__attribute__ ((indirect_branch("thunk-extern")))
+void
+bar (void)
+{ /* { dg-error "'-mindirect-branch=thunk-extern', '-fcf-protection=branch' and '-fcheck-pointer-bounds' are not compatible" } */
+}

gcc/testsuite/gcc.target/i386/indirect-thunk-attr-13.c

+/* { dg-do compile { target { ! x32 } } } */
+/* { dg-options "-O2 -mindirect-branch=keep -fcf-protection -mcet -fcheck-pointer-bounds -mmpx" } */
+
+__attribute__ ((indirect_branch("thunk-inline")))
+void
+bar (void)
+{
+}

gcc/testsuite/gcc.target/i386/indirect-thunk-attr-14.c

+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -fno-pic -fplt -mindirect-branch=keep -fcf-protection -mcet" } */
+
+extern void (*bar) (void);
+
+__attribute__ ((indirect_branch("thunk-extern")))
+void
+foo (void)
+{
+  bar ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*__x86_indirect_thunk" } } */
+/* { dg-final { scan-assembler-not "jmp\[ \t\]*__x86_indirect_thunk_nt" } } */

gcc/testsuite/gcc.target/i386/indirect-thunk-attr-15.c

+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -mindirect-branch-register -mfunction-return=keep -fno-pic -fplt -mindirect-branch=keep -fcf-protection -mcet" } */
+
+extern void (*bar) (void);
+
+__attribute__ ((indirect_branch("thunk-extern")))
+void
+foo (void)
+{
+  bar ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*__x86_indirect_thunk" } } */
+/* { dg-final { scan-assembler-not "jmp\[ \t\]*__x86_indirect_thunk_nt" } } */

gcc/testsuite/gcc.target/i386/indirect-thunk-attr-16.c

+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -mindirect-branch-register -mfunction-return=keep -fno-pic -fplt -mindirect-branch=keep -fcf-protection -mcet" } */
+
+extern void (*bar) (void) __attribute__((nocf_check));
+
+__attribute__ ((indirect_branch("thunk-extern")))
+void
+foo (void)
+{
+  bar ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*__x86_indirect_thunk_nt_(r|e)" } } */

gcc/testsuite/gcc.target/i386/indirect-thunk-extern-10.c

+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -mindirect-branch-register -mfunction-return=keep -fno-pic -fplt -mindirect-branch=thunk-extern -fcf-protection -mcet" } */
+
+extern void (*bar) (void) __attribute__((nocf_check));
+
+void
+foo (void)
+{
+  bar ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*__x86_indirect_thunk_nt_(r|e)" } } */

gcc/testsuite/gcc.target/i386/indirect-thunk-extern-8.c

+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -fno-pic -fplt -mindirect-branch=thunk-extern -fcf-protection -mcet" } */
+
+extern void (*bar) (void);
+
+void
+foo (void)
+{
+  bar ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*__x86_indirect_thunk" } } */
+/* { dg-final { scan-assembler-not "jmp\[ \t\]*__x86_indirect_thunk_nt" } } */

gcc/testsuite/gcc.target/i386/indirect-thunk-extern-9.c

+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -mindirect-branch-register -mfunction-return=keep -fno-pic -fplt -mindirect-branch=thunk-extern -fcf-protection -mcet" } */
+
+extern void (*bar) (void);
+
+void
+foo (void)
+{
+  bar ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*__x86_indirect_thunk" } } */
+/* { dg-final { scan-assembler-not "jmp\[ \t\]*__x86_indirect_thunk_nt" } } */