[PATCH] [PR/target 100316] Allow constant address for __builtin___clear_cache.

[Kito Cheng <kito.cheng@sifive.com>]

__builtin___clear_cache was able to accept constant address for the
argument, but it seems no longer accept recently, and it even not
accept constant address which is hold in variable when optimization is
enable:

```
void foo3(){
  void *yy = (void*)0x1000;
  __builtin___clear_cache(yy, yy);
}
```

So this patch make BEGIN and END accept VOIDmode, like cselib_lookup_mem did per
Jim Wilson's suggestion.

```
static cselib_val *
cselib_lookup_mem (rtx x, int create)
{
  ...
  addr_mode = GET_MODE (XEXP (x, 0));
  if (addr_mode == VOIDmode)
    addr_mode = Pmode;
```

gcc/ChangeLog:

	PR target/100316
	* builtins.c (maybe_emit_call_builtin___clear_cache): Allow
	VOIDmode for begin and end.

gcc/testsuite/ChangeLog:

	PR target/100316
	* gcc.c-torture/compile/pr100316.c: New.
---
 gcc/builtins.c                                 |  6 ++++--
 gcc/testsuite/gcc.c-torture/compile/pr100316.c | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr100316.c

diff --git a/gcc/builtins.c b/gcc/builtins.c
index 3e57eb03af0..960f07121fc 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -5163,8 +5163,10 @@ default_emit_call_builtin___clear_cache (rtx begin, rtx end)
 void
 maybe_emit_call_builtin___clear_cache (rtx begin, rtx end)
 {
-  if ((GET_MODE (begin) != ptr_mode && GET_MODE (begin) != Pmode)
-      || (GET_MODE (end) != ptr_mode && GET_MODE (end) != Pmode))
+  if ((GET_MODE (begin) != ptr_mode && GET_MODE (begin) != Pmode
+       && GET_MODE (begin) != VOIDmode)
+      || (GET_MODE (end) != ptr_mode && GET_MODE (end) != Pmode
+	  && GET_MODE (begin) != VOIDmode))
     {
       error ("both arguments to %<__builtin___clear_cache%> must be pointers");
       return;
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr100316.c b/gcc/testsuite/gcc.c-torture/compile/pr100316.c
new file mode 100644
index 00000000000..38eca86f49f
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr100316.c
@@ -0,0 +1,18 @@
+void foo(){
+  __builtin___clear_cache(0, 0);
+}
+
+void foo1(){
+  __builtin___clear_cache((void*)0, (void*)0);
+}
+
+void foo2(){
+  void *yy = 0;
+  __builtin___clear_cache(yy, yy);
+}
+
+void foo3(){
+  void *yy = (void*)0x1000;
+  __builtin___clear_cache(yy, yy);
+}
+
-- 
2.33.0