From 77d372abec0fbf2cfe922e3140ee3410248f979e Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 14 Jan 2021 05:56:46 -0800
Subject: [PATCH] x86: Error on -fcf-protection with incompatible target

-fcf-protection with CF_BRANCH inserts ENDBR32 at function entries.
ENDBR32 is NOP only on 64-bit processors and 32-bit TARGET_CMOV
processors.  Issue an error for -fcf-protection with CF_BRANCH when
compiling for 32-bit non-TARGET_CMOV targets.

gcc/

	PR target/98667
	* config/i386/i386-options.c (ix86_option_override_internal):
	Issue an error for -fcf-protection with CF_BRANCH when compiling
	for 32-bit non-TARGET_CMOV targets.

gcc/testsuite/

	PR target/98667
	* gcc.target/i386/pr98667-1.c: New file.
	* gcc.target/i386/pr98667-2.c: Likewise.
	* gcc.target/i386/pr98667-3.c: Likewise.
---
 gcc/config/i386/i386-options.c            | 8 +++++++-
 gcc/testsuite/gcc.target/i386/pr98667-1.c | 9 +++++++++
 gcc/testsuite/gcc.target/i386/pr98667-2.c | 9 +++++++++
 gcc/testsuite/gcc.target/i386/pr98667-3.c | 7 +++++++
 4 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr98667-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr98667-2.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr98667-3.c

diff --git a/gcc/config/i386/i386-options.c b/gcc/config/i386/i386-options.c
index 6819a042389..a70f6edf7b0 100644
--- a/gcc/config/i386/i386-options.c
+++ b/gcc/config/i386/i386-options.c
@@ -3014,8 +3014,14 @@ ix86_option_override_internal (bool main_args_p,
     }
 
   if (opts->x_flag_cf_protection != CF_NONE)
-    opts->x_flag_cf_protection
+    {
+      if ((opts->x_flag_cf_protection & CF_BRANCH) == CF_BRANCH
+	  && !TARGET_64BIT && !TARGET_CMOV)
+	error ("%<-fcf-protection%> is not compatible with this target");
+
+      opts->x_flag_cf_protection
       = (cf_protection_level) (opts->x_flag_cf_protection | CF_SET);
+    }
 
   if (ix86_tune_features [X86_TUNE_AVOID_256FMA_CHAINS])
     SET_OPTION_IF_UNSET (opts, opts_set, param_avoid_fma_max_bits, 256);
diff --git a/gcc/testsuite/gcc.target/i386/pr98667-1.c b/gcc/testsuite/gcc.target/i386/pr98667-1.c
new file mode 100644
index 00000000000..5bf0c9285a8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr98667-1.c
@@ -0,0 +1,9 @@
+/* { dg-do compile { target ia32 } } */
+/* { dg-options "-O2 -fcf-protection -march=i486" } */
+
+void
+test (void)
+{
+}
+
+/* { dg-error "'-fcf-protection' is not compatible with this target" "" { target *-*-* } 0 } */
diff --git a/gcc/testsuite/gcc.target/i386/pr98667-2.c b/gcc/testsuite/gcc.target/i386/pr98667-2.c
new file mode 100644
index 00000000000..bc3a78c9641
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr98667-2.c
@@ -0,0 +1,9 @@
+/* { dg-do compile { target ia32 } } */
+/* { dg-options "-O2 -fcf-protection=branch -march=i486" } */
+
+void
+test (void)
+{
+}
+
+/* { dg-error "'-fcf-protection' is not compatible with this target" "" { target *-*-* } 0 } */
diff --git a/gcc/testsuite/gcc.target/i386/pr98667-3.c b/gcc/testsuite/gcc.target/i386/pr98667-3.c
new file mode 100644
index 00000000000..a6ea6d04331
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr98667-3.c
@@ -0,0 +1,7 @@
+/* { dg-do compile { target ia32 } } */
+/* { dg-options "-O2 -fcf-protection=return -march=i486" } */
+
+void
+test (void)
+{
+}
-- 
2.30.2