guile: fix make-value with pointer type

Calling the `make-value' procedure with an integer value and a pointer
type for the #:type argument triggers a failed assertion in
`get_unsigned_type_max', as that function doesn't consider pointers to
be an unsigned type. This commit fixes the issue by adding a separate
code path for pointers.

As previously suggested, range checking is done using a new helper
function in gdbtypes.

gdb/ChangeLog:

2021-07-30  George Barrett  <bob@bob131.so>

	* gdbtypes.h (get_pointer_type_max): Add declaration.
	* gdbtypes.c (get_pointer_type_max): Add definition for new
	helper function.
	* guile/scm-math.c (vlscm_convert_typed_number): Add code path
	for handling conversions to pointer types without failing an
	assert.

gdb/testsuite/ChangeLog:

2021-07-30  George Barrett  <bob@bob131.so>

	* gdb.guile/scm-math.exp (test_value_numeric_ops): Add test
	for creating pointers with make-value.
	(test_make_pointer_value, test_pointer_numeric_range): Add
	test procedures containing checks for integer-to-pointer
	validation.

Change-Id: I9994dd1c848840a3d995f745e6d72867732049f0

gdb/gdbtypes.c

@@ -1924,6 +1924,21 @@ get_signed_type_minmax (struct type *type, LONGEST *min, LONGEST *max)
   *max = ((ULONGEST) 1 << (n - 1)) - 1;
 }
 
+/* Return the largest value representable by pointer type TYPE. */
+
+CORE_ADDR
+get_pointer_type_max (struct type *type)
+{
+  unsigned int n;
+
+  type = check_typedef (type);
+  gdb_assert (type->code () == TYPE_CODE_PTR);
+  gdb_assert (TYPE_LENGTH (type) <= sizeof (CORE_ADDR));
+
+  n = TYPE_LENGTH (type) * TARGET_CHAR_BIT;
+  return ((((CORE_ADDR) 1 << (n - 1)) - 1) << 1) | 1;
+}
+
 /* Internal routine called by TYPE_VPTR_FIELDNO to return the value of
    cplus_stuff.vptr_fieldno.
 

gdb/gdbtypes.h

@@ -2523,6 +2523,8 @@ extern ULONGEST get_unsigned_type_max (struct type *);
 
 extern void get_signed_type_minmax (struct type *, LONGEST *, LONGEST *);
 
+extern CORE_ADDR get_pointer_type_max (struct type *);
+
 /* * Resolve all dynamic values of a type e.g. array bounds to static values.
    ADDR specifies the location of the variable the type is bound to.
    If TYPE has no dynamic properties return TYPE; otherwise a new type with

gdb/guile/scm-math.c

@@ -524,8 +524,7 @@ vlscm_convert_typed_number (const char *func_name, int obj_arg_pos, SCM obj,
 			    int type_arg_pos, SCM type_scm, struct type *type,
 			    struct gdbarch *gdbarch, SCM *except_scmp)
 {
-  if (is_integral_type (type)
-      || type->code () == TYPE_CODE_PTR)
+  if (is_integral_type (type))
     {
       if (type->is_unsigned ())
 	{
@@ -556,6 +555,19 @@ vlscm_convert_typed_number (const char *func_name, int obj_arg_pos, SCM obj,
 	  return value_from_longest (type, gdbscm_scm_to_longest (obj));
 	}
     }
+  else if (type->code () == TYPE_CODE_PTR)
+    {
+      CORE_ADDR max = get_pointer_type_max (type);
+      if (!scm_is_unsigned_integer (obj, 0, max))
+	{
+	  *except_scmp
+	    = gdbscm_make_out_of_range_error (func_name,
+					      obj_arg_pos, obj,
+					_("value out of range for type"));
+	  return NULL;
+	}
+      return value_from_pointer (type, gdbscm_scm_to_ulongest (obj));
+    }
   else if (type->code () == TYPE_CODE_FLT)
     return value_from_host_double (type, scm_to_double (obj));
   else

gdb/testsuite/gdb.guile/scm-math.exp

@@ -137,6 +137,15 @@ proc test_value_numeric_ops {} {
     gdb_test "gu (print (value-sub b a))" \
 	"= 3" "subtract two pointer values"
 
+    # Test pointer creation.
+
+    gdb_test_no_output "gu (define void-pointer-type (type-pointer (arch-void-type (current-arch))))"
+    gdb_scm_test_silent_cmd "gu (define null-pointer (make-value 0 #:type void-pointer-type))" \
+	"test make-value with pointer type"
+    gdb_test "gu (print null-pointer)" "= 0x0"
+    gdb_test "gu (print (equal? (value-type null-pointer) void-pointer-type))" \
+	"= #t"
+
     # Test some invalid operations.
 
     gdb_test_multiple "gu (print (value-add i '()))" "catch error in guile type conversion" {
@@ -237,6 +246,36 @@ proc test_value_numeric_ranges {} {
     }
 }
 
+# Helper routine for test_pointer_numeric_range.
+
+proc test_make_pointer_value { size } {
+    set max [get_max_uint $size]
+    set max_hex [string repeat "f" [expr "$size / 4"]]
+
+    gdb_test "gu (print (make-value $max #:type void-pointer-type))" \
+	"= 0x$max_hex" "test make-value void* max"
+    gdb_test "gu (print (make-value 0 #:type void-pointer-type))" \
+	"= 0x0" "test make-value void* 0"
+
+    gdb_test "gu (print (make-value (+ $max 1) #:type void-pointer-type))" \
+	"ERROR.*Out of range.*" "test make-value void* max+1"
+    gdb_test "gu (print (make-value -1 #:type void-pointer-type))" \
+	"ERROR.*Out of range.*" "test make-value void* -1"
+}
+
+proc test_pointer_numeric_range {} {
+    # We can't assume anything about sizeof (void*) on the target.
+    # Keep it simple for now, this will cover everything important for
+    # the major targets.
+    set pointer_size [get_sizeof "void*" 0]
+    if { $pointer_size == 4 } {
+	test_make_pointer_value 32
+    }
+    if { $pointer_size == 8 } {
+	test_make_pointer_value 64
+    }
+}
+
 proc test_value_boolean {} {
     # Note: Boolean values print as 0,1 because they are printed in the
     # current language (in this case C).
@@ -305,5 +344,6 @@ if ![gdb_guile_runto_main] {
 
 test_value_numeric_ops
 test_value_numeric_ranges
+test_pointer_numeric_range
 test_value_boolean
 test_value_compare