From: Alexandre Oliva <oliva@adacore.com>
Date: Wed, 15 Dec 2021 05:22:33 +0000 (-0300)
Subject: [PR100843] store by mult pieces: punt on max_len < min_len
X-Git-Tag: basepoints/gcc-13~2330
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c95a9f1ee7ebd461cbced455271a993bae3a42b6;p=thirdparty%2Fgcc.git

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

The testcase confuses the code that detects min and max len for the
memset, so max_len ends up less than min_len.  That shouldn't be
possible, but the testcase requires us to handle this case.

The store-by-mult-pieces algorithm actually relies on min and max
lengths, so if we find them to be inconsistent, the best we can do is
punting.


for  gcc/ChangeLog

	PR middle-end/100843
	* builtins.c (try_store_by_multiple_pieces): Fail if min_len
	is greater than max_len.

for  gcc/testsuite/ChangeLog

	PR middle-end/100843
	* gcc.dg/pr100843.c: New.
---

diff --git a/gcc/builtins.c b/gcc/builtins.c
index 03829c03a5a1..304d87dafb75 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 000000000000..695a2ec3f681
--- /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);
+}