re PR tree-optimization/83640 (ICE in generic_overlap, at gimple-ssa-warn-restrict.c:814)

2018-01-06  Martin Sebor  <msebor@redhat.com>

	PR tree-optimization/83640
	* gimple-ssa-warn-restrict.c (builtin_access::builtin_access): Avoid
	subtracting negative offset from size.
	(builtin_access::overlap): Adjust offset bounds of the access to fall
	within the size of the object if possible.

	PR tree-optimization/83640
	* gcc.dg/Wrestrict-6.c: New test.
	* gcc.dg/pr83640.c: New test.

From-SVN: r256319

gcc/ChangeLog

+2018-01-06  Martin Sebor  <msebor@redhat.com>
+
+	PR tree-optimization/83640
+	* gimple-ssa-warn-restrict.c (builtin_access::builtin_access): Avoid
+	subtracting negative offset from size.
+	(builtin_access::overlap): Adjust offset bounds of the access to fall
+	within the size of the object if possible.
+
 2018-01-06  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	PR rtl-optimization/83699

gcc/gimple-ssa-warn-restrict.c

@@ -1371,8 +1371,6 @@ maybe_diag_overlap (location_t loc, gcall *call, builtin_access &acs)
       return true;
     }
 
-  /* Issue "may overlap" diagnostics below.  */
-
   /* Use more concise wording when one of the offsets is unbounded
      to avoid confusing the user with large and mostly meaningless
      numbers.  */

gcc/testsuite/ChangeLog

+2018-01-06  Martin Sebor  <msebor@redhat.com>
+
+	PR tree-optimization/83640
+	* gcc.dg/Wrestrict-6.c: New test.
+	* gcc.dg/pr83640.c: New test.
+
 2018-01-06  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	* gcc.target/aarch64/reg-alloc-1.c: New test.

gcc/testsuite/gcc.dg/Wrestrict-6.c

+/* PR tree-optimization/83640 - ice in generic_overlap, at
+   gimple-ssa-warn-restrict.c:814
+   Test to verify that a pointer offset range whose upper bound is less
+   than its lower bound (when interpreted as a signed integer) is handled
+   correctly.
+   { dg-do compile }
+   { dg-options "-O2 -Wrestrict" }  */
+
+#include "range.h"
+
+extern char* strcpy (char*, const char*);
+extern char* stpcpy (char*, const char*);
+
+void sink (void*);
+
+void warn_2_smax_p2 (void)
+{
+  char a[7] = "01234";
+
+  char *d = a;
+
+  ptrdiff_t i = UR (2, DIFF_MAX + (size_t)2);
+
+  strcpy (d, d + i);          /* { dg-warning "accessing between 0 and 4 bytes at offsets 0 and \\\[2, -\[0-9\]+] may overlap up to 2 bytes at offset 2" } */
+
+  sink (d);
+}
+
+void nowarn_3_smax_p2 (void)
+{
+  char a[7] = "12345";
+
+  char *d = a;
+
+  ptrdiff_t i = UR (3, DIFF_MAX + (size_t)2);
+
+  strcpy (d, d + i);
+
+  sink (d);
+}
+
+void warn_2u_smax_p2 (void)
+{
+  char a[7] = "23456";
+
+  char *d = a;
+
+  size_t i = UR (2, DIFF_MAX + (size_t)2);
+
+  strcpy (d, d + i);          /* { dg-warning "accessing between 0 and 4 bytes at offsets 0 and \\\[2, -\[0-9\]+] may overlap up to 2 bytes at offset 2" } */
+
+  sink (d);
+}
+
+void nowarn_3u_smax_p2 (void)
+{
+  char a[7] = "34567";
+
+  char *d = a;
+
+  size_t i = UR (3, DIFF_MAX + (size_t)2);
+
+  strcpy (d, d + i);
+
+  sink (d);
+}

gcc/testsuite/gcc.dg/pr83640.c

+/* PR tree-optimization/83640 - ice in generic_overlap, at
+   gimple-ssa-warn-restrict.c:814
+   { dg-do compile }
+   { dg-options "-O2 -Wall" }  */
+
+char *foo (void);
+
+void
+bar (char *b, char *c)
+{
+  b = c;
+  c = foo ();
+  __builtin_strcat (c, "*/");
+  __builtin_strcat (c, b);
+}