[gcc(refs/users/aoliva/heads/testme)] [PR100843] store by mult pieces: punt on max_len < min_len

[gcc(refs/users/aoliva/heads/testme)] [PR100843] store by mult pieces: punt on max_len < min_len

[Alexandre Oliva]

https://gcc.gnu.org/g:0709212ebe9f91ed686f2a5ea1ccfceba175fe53

commit 0709212ebe9f91ed686f2a5ea1ccfceba175fe53
Author: Alexandre Oliva <oliva@gnu.org>
Date:   Thu Dec 9 01:44:17 2021 -0300

    [PR100843] store by mult pieces: punt on max_len < min_len

Diff:
---
 gcc/builtins.c                  | 3 ++-
 gcc/testsuite/gcc.dg/pr100843.c | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/gcc/builtins.c b/gcc/builtins.c
index 03829c03a5a..304d87dafb7 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -3963,7 +3963,8 @@ try_store_by_multiple_pieces (rtx to, rtx len, unsigned int ctz_len,
   else if (max_len == min_len)
     blksize = max_len;
   else
-    gcc_unreachable ();
+    /* Huh, max_len < min_len?  Punt.  See pr100843.c.  */
+    return false;
   if (min_len >= blksize)
     {
       min_len -= blksize;
diff --git a/gcc/testsuite/gcc.dg/pr100843.c b/gcc/testsuite/gcc.dg/pr100843.c
new file mode 100644
index 00000000000..695a2ec3f68
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr100843.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -w" } */
+
+char c;
+void *memset();
+void test_integer_conversion_memset(void *d) {
+  memset(d, '\0', c);
+}