From: Richard Biener <rguenther@suse.de>
Date: Wed, 15 Jun 2022 08:54:48 +0000 (+0200)
Subject: tree-optimization/105969 - FPE with array diagnostics
X-Git-Tag: basepoints/gcc-14~6102
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=edb9330c29fe8a0a0b76df6fafd6a223a4d0e41f;p=thirdparty%2Fgcc.git

tree-optimization/105969 - FPE with array diagnostics

For a [0][0] array we have to be careful when dividing by the element
size which is zero for the outermost dimension.  Luckily the division
is only for an overflow check which is pointless for array size zero.

2022-06-15  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/105969
	* gimple-ssa-sprintf.cc (get_origin_and_offset_r): Avoid division
	by zero in overflow check.

	* gcc.dg/pr105969.c: New testcase.
---

diff --git a/gcc/gimple-ssa-sprintf.cc b/gcc/gimple-ssa-sprintf.cc
index 6bd27302213..a888b5ac7d5 100644
--- a/gcc/gimple-ssa-sprintf.cc
+++ b/gcc/gimple-ssa-sprintf.cc
@@ -2319,7 +2319,7 @@ get_origin_and_offset_r (tree x, HOST_WIDE_INT *fldoff, HOST_WIDE_INT *fldsize,
 
 	if (byteoff < HOST_WIDE_INT_MAX
 	    && elbytes < HOST_WIDE_INT_MAX
-	    && byteoff / elbytes == idx)
+	    && (elbytes == 0 || byteoff / elbytes == idx))
 	  {
 	    /* For in-bounds constant offsets into constant-sized arrays
 	       bump up *OFF, and for what's likely arrays or structs of
diff --git a/gcc/testsuite/gcc.dg/pr105969.c b/gcc/testsuite/gcc.dg/pr105969.c
new file mode 100644
index 00000000000..52c63fc2efe
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr105969.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+struct A
+{
+  char a[0][0][0];
+};
+extern struct A b[][2];
+void f (void)
+{
+  __builtin_sprintf (b[0][0].a[1][0], "%s", b[0][0].a[1][0]); /* { dg-warning "past the end" } */
+  /* { dg-warning "overlaps destination" "" { target *-*-* } .-1 } */
+}