Force ENDBR immediate into memory.

gcc/
	PR target/96350
	* config/i386/i386.c (ix86_legitimate_constant_p): Return
	false for ENDBR immediate.
	(ix86_legitimate_address_p): Ditto.
	* config/i386/predicates.md
	(x86_64_immediate_operand): Exclude ENDBR immediate.
	(x86_64_zext_immediate_operand): Ditto.
	(x86_64_dwzext_immediate_operand): Ditto.
	(ix86_endbr_immediate_operand): New predicate.

gcc/testsuite
	* gcc.target/i386/endbr_immediate.c: New test.

gcc/config/i386/i386.c

@@ -10056,6 +10056,9 @@ ix86_legitimate_constant_p (machine_mode mode, rtx x)
       break;
 
     CASE_CONST_SCALAR_INT:
+      if (ix86_endbr_immediate_operand (x, VOIDmode))
+	return false;
+
       switch (mode)
 	{
 	case E_TImode:
@@ -10449,6 +10452,9 @@ ix86_legitimate_address_p (machine_mode, rtx addr, bool strict)
   /* Validate displacement.  */
   if (disp)
     {
+      if (ix86_endbr_immediate_operand (disp, VOIDmode))
+	return false;
+
       if (GET_CODE (disp) == CONST
 	  && GET_CODE (XEXP (disp, 0)) == UNSPEC
 	  && XINT (XEXP (disp, 0), 1) != UNSPEC_MACHOPIC_OFFSET)

gcc/config/i386/predicates.md

@@ -130,10 +130,35 @@
 (define_predicate "symbol_operand"
   (match_code "symbol_ref"))
 
+;; Return true if VALUE is an ENDBR opcode in immediate field.
+(define_predicate "ix86_endbr_immediate_operand"
+  (match_code "const_int")
+{
+  if (flag_cf_protection & CF_BRANCH)
+     {
+       unsigned HOST_WIDE_INT imm = UINTVAL (op);
+       unsigned HOST_WIDE_INT val = TARGET_64BIT ? 0xfa1e0ff3 : 0xfb1e0ff3;
+
+       if (imm == val)
+	 return 1;
+
+       /* NB: Encoding is byte based.  */
+       if (TARGET_64BIT)
+	 for (; imm >= val; imm >>= 8)
+	   if (imm == val)
+	     return 1;
+      }
+
+  return 0;
+})
+
 ;; Return true if VALUE can be stored in a sign extended immediate field.
 (define_predicate "x86_64_immediate_operand"
   (match_code "const_int,symbol_ref,label_ref,const")
 {
+  if (ix86_endbr_immediate_operand (op, VOIDmode))
+    return false;
+
   if (!TARGET_64BIT)
     return immediate_operand (op, mode);
 
@@ -260,6 +285,9 @@
 (define_predicate "x86_64_zext_immediate_operand"
   (match_code "const_int,symbol_ref,label_ref,const")
 {
+  if (ix86_endbr_immediate_operand (op, VOIDmode))
+    return false;
+
   switch (GET_CODE (op))
     {
     case CONST_INT:
@@ -374,6 +402,9 @@
 (define_predicate "x86_64_dwzext_immediate_operand"
   (match_code "const_int,const_wide_int")
 {
+  if (ix86_endbr_immediate_operand (op, VOIDmode))
+    return false;
+
   switch (GET_CODE (op))
     {
     case CONST_INT:

gcc/testsuite/gcc.target/i386/endbr_immediate.c

@@ -0,0 +1,198 @@
+/* PR target/96350 */
+/* { dg-do compile } */
+/* { dg-options "-fcf-protection -O2" } */
+/* { dg-final { scan-assembler-not "$-81915917" { target { ia32 } } } } */
+/* { dg-final { scan-assembler-not "$-98693133" { target { ! ia32 } } } } *
+/* { dg-final { scan-assembler-not "$-423883778574778368" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "\[ \t\]*-81915917" { target { ia32 } } } } */
+/* { dg-final { scan-assembler "\[ \t\]*-98693133" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "\[ \t\]*-423883778574778368" { target { ! ia32 } } } } */
+
+
+#ifdef __x86_64__
+#define ENDBR_IMMEDIATE 0xfa1e0ff3
+#define EXTEND_ENDBR_IMMEDIATE 0xfa1e0ff300000000
+#else
+#define ENDBR_IMMEDIATE 0xfb1e0ff3
+#define EXTEND_ENDBR_IMMEDIATE 0xfffb1e0ff300
+#endif
+
+int
+foo (int a)
+{
+  return a + ENDBR_IMMEDIATE;
+}
+
+int
+foo2 (int a)
+{
+  return a - ENDBR_IMMEDIATE;
+}
+
+int
+foo3 (int a)
+{
+  return a * ENDBR_IMMEDIATE;
+}
+
+int
+foo4 (int a)
+{
+  return a | ENDBR_IMMEDIATE;
+}
+
+int
+foo5 (int a)
+{
+  return a ^ ENDBR_IMMEDIATE;
+}
+
+int
+foo6 (int a)
+{
+  return a & ENDBR_IMMEDIATE;
+}
+
+int
+foo7 (int a)
+{
+  return a > ENDBR_IMMEDIATE;
+}
+
+int
+foo8 (int a)
+{
+  return ENDBR_IMMEDIATE;
+}
+
+int
+foo9 (int* p)
+{
+  return *(p + ENDBR_IMMEDIATE);
+}
+
+int
+foo10 (int* p)
+{
+  return *(int*) ENDBR_IMMEDIATE;
+}
+
+long long
+foo11 (long long a)
+{
+  return a + EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo12 (long long a)
+{
+  return a - EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo13 (long long a)
+{
+  return a * EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo14 (long long a)
+{
+  return a | EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo15 (long long a)
+{
+  return a ^ EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo16 (long long a)
+{
+  return a & EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo17 (long long a)
+{
+  return a > EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo18 (long long a)
+{
+  return EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo19 (long long* p)
+{
+  return *(p + EXTEND_ENDBR_IMMEDIATE);
+}
+
+long long
+foo20 (long long* p)
+{
+  return *(long long*) EXTEND_ENDBR_IMMEDIATE;
+}
+
+long long
+foo21 (int a)
+{
+  return a + ENDBR_IMMEDIATE;
+}
+
+long long
+foo22 (int a)
+{
+  return a - ENDBR_IMMEDIATE;
+}
+
+long long
+foo23 (long long a)
+{
+  return a * ENDBR_IMMEDIATE;
+}
+
+long long
+foo24 (int a)
+{
+  return a | ENDBR_IMMEDIATE;
+}
+
+long long
+foo25 (int a)
+{
+  return a ^ ENDBR_IMMEDIATE;
+}
+
+long long
+foo26 (int a)
+{
+  return a & ENDBR_IMMEDIATE;
+}
+
+long long
+foo27 (int a)
+{
+  return a > ENDBR_IMMEDIATE;
+}
+
+long long
+foo28 (int a)
+{
+  return ENDBR_IMMEDIATE;
+}
+
+long long
+foo29 (int* p)
+{
+  return *(p + ENDBR_IMMEDIATE);
+}
+
+long long
+foo30 (int* p)
+{
+  return *(long long*) ENDBR_IMMEDIATE;
+}