aarch64: Add front-end argument type checking for target builtins

In implementing the ACLE read/write system register builtins it was
observed that leaving argument type checking to be done at expand-time
meant that poorly-formed function calls were being "fixed" by certain
optimization passes, meaning bad code wasn't being properly picked up
in checking.

Example:

  const char *regname = "amcgcr_el0";
  long long a = __builtin_aarch64_rsr64 (regname);

is reduced by the ccp1 pass to

  long long a = __builtin_aarch64_rsr64 ("amcgcr_el0");

As these functions require an argument of STRING_CST type, there needs
to be a check carried out by the front-end capable of picking this up.

The introduced `check_general_builtin_call' function will be called by
the TARGET_CHECK_BUILTIN_CALL hook whenever a call to a builtin
belonging to the AARCH64_BUILTIN_GENERAL category is encountered,
carrying out any appropriate checks associated with a particular
builtin function code.

gcc/ChangeLog:

	* config/aarch64/aarch64-builtins.cc (aarch64_general_check_builtin_call):
	New.
	* config/aarch64/aarch64-c.cc (aarch64_check_builtin_call):
	Add `aarch64_general_check_builtin_call' call.
	* config/aarch64/aarch64-protos.h (aarch64_general_check_builtin_call):
	New.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/acle/rwsr-3.c: New.

4 files changed, 55 insertions, 2 deletions

diff --git a/gcc/config/aarch64/aarch64-builtins.cc b/gcc/config/aarch64/aarch64-builtins.cc
index a004e06..f780b10 100644
--- a/gcc/config/aarch64/aarch64-builtins.cc
+++ b/gcc/config/aarch64/aarch64-builtins.cc
@@ -2127,6 +2127,37 @@ aarch64_general_builtin_decl (unsigned code, bool)
   return aarch64_builtin_decls[code];
 }
 
+bool
+aarch64_general_check_builtin_call (location_t location, vec<location_t>,
+			    unsigned int code, tree fndecl,
+			    unsigned int nargs ATTRIBUTE_UNUSED, tree *args)
+{
+  switch (code)
+    {
+    case AARCH64_RSR:
+    case AARCH64_RSRP:
+    case AARCH64_RSR64:
+    case AARCH64_RSRF:
+    case AARCH64_RSRF64:
+    case AARCH64_WSR:
+    case AARCH64_WSRP:
+    case AARCH64_WSR64:
+    case AARCH64_WSRF:
+    case AARCH64_WSRF64:
+      tree addr = STRIP_NOPS (args[0]);
+      if (TREE_CODE (TREE_TYPE (addr)) != POINTER_TYPE
+	  || TREE_CODE (addr) != ADDR_EXPR
+	  || TREE_CODE (TREE_OPERAND (addr, 0)) != STRING_CST)
+	{
+	  error_at (location, "first argument to %qD must be a string literal",
+		    fndecl);
+	  return false;
+	}
+    }
+  /* Default behavior.  */
+  return true;
+}
+
 typedef enum
 {
   SIMD_ARG_COPY_TO_REG,
diff --git a/gcc/config/aarch64/aarch64-c.cc b/gcc/config/aarch64/aarch64-c.cc
index dd4b325..18422bb 100644
--- a/gcc/config/aarch64/aarch64-c.cc
+++ b/gcc/config/aarch64/aarch64-c.cc
@@ -394,8 +394,8 @@ aarch64_check_builtin_call (location_t loc, vec<location_t> arg_loc,
   switch (code & AARCH64_BUILTIN_CLASS)
     {
     case AARCH64_BUILTIN_GENERAL:
-      return true;
-
+      return aarch64_general_check_builtin_call (loc, arg_loc, subcode,
+						 orig_fndecl, nargs, args);
     case AARCH64_BUILTIN_SVE:
       return aarch64_sve::check_builtin_call (loc, arg_loc, subcode,
 					      orig_fndecl, nargs, args);
diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index 9e09cf7..60ff61f 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -1002,6 +1002,10 @@ tree aarch64_general_builtin_rsqrt (unsigned int);
 void handle_arm_acle_h (void);
 void handle_arm_neon_h (void);
 
+bool aarch64_general_check_builtin_call (location_t, vec<location_t>,
+					 unsigned int, tree, unsigned int,
+					 tree *);
+
 namespace aarch64_sve {
   void init_builtins ();
   void handle_arm_sve_h ();
diff --git a/gcc/testsuite/gcc.target/aarch64/acle/rwsr-3.c b/gcc/testsuite/gcc.target/aarch64/acle/rwsr-3.c
new file mode 100644
index 0000000..aadd04a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/acle/rwsr-3.c
@@ -0,0 +1,18 @@
+/* Test the __arm_[r,w]sr ACLE intrinsics family.  */
+/* Ensure that illegal behavior is rejected by the compiler.  */
+
+/* { dg-do compile } */
+/* { dg-options "-std=c2x -O3 -march=armv8-a" } */
+
+#include <arm_acle.h>
+
+void
+test_non_const_sysreg_name ()
+{
+  const char *regname = "trcseqstr";
+  long long a = __arm_rsr64 (regname); /* { dg-error "first argument to '__builtin_aarch64_rsr64' must be a string literal" } */
+  __arm_wsr64 (regname, a); /* { dg-error "first argument to '__builtin_aarch64_wsr64' must be a string literal" } */
+
+  long long b = __arm_rsr64 (nullptr); /* { dg-error "first argument to '__builtin_aarch64_rsr64' must be a string literal" } */
+  __arm_wsr64 (nullptr, b); /* { dg-error "first argument to '__builtin_aarch64_wsr64' must be a string literal" } */
+}