tree-ssa-strlen.c (get_addr_stridx): Add argument and use it.

gcc/ChangeLog:

	* tree-ssa-strlen.c (get_addr_stridx): Add argument and use it.
	(handle_store): Pass argument to get_addr_stridx.

gcc/testsuite/ChangeLog:

	* gcc.dg/strlenopt-89.c: New test.
	* gcc.dg/strlenopt-90.c: New test.
	* gcc.dg/Wstringop-overflow-20.c: New test.

From-SVN: r277546

6 files changed, 227 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3f4f2dc..8b8a6c6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 2019-10-28  Martin Sebor  <msebor@redhat.com>
 
+	* tree-ssa-strlen.c (get_addr_stridx): Add argument and use it.
+	(handle_store): Pass argument to get_addr_stridx.
+
+2019-10-28  Martin Sebor  <msebor@redhat.com>
+
 	PR tree-optimization/92226
 	* tree-ssa-strlen.c (compare_nonzero_chars): Return -1 also when
 	the offset is in the open range outlined by SI's length.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8f9859f..a3ef286 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,11 @@
 2019-10-28  Martin Sebor  <msebor@redhat.com>
 
+	* gcc.dg/strlenopt-89.c: New test.
+	* gcc.dg/strlenopt-90.c: New test.
+	* gcc.dg/Wstringop-overflow-20.c: New test.
+
+2019-10-28  Martin Sebor  <msebor@redhat.com>
+
 	PR tree-optimization/92226
 	* gcc.dg/strlenopt-88.c: New test.
 
diff --git a/gcc/testsuite/gcc.dg/Wstringop-overflow-20.c b/gcc/testsuite/gcc.dg/Wstringop-overflow-20.c
new file mode 100644
index 0000000..4a6fe8e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wstringop-overflow-20.c
@@ -0,0 +1,40 @@
+/* PR tree-optimization/92226 - live nul char store to array eliminated
+   Test to verify warnings are issued for overflow detected thanks to
+   the enhancement committed on top of the fix for PR 92226.
+   { dg-do compile }
+   { dg-options "-O2 -Wall -Wno-array-bounds -ftrack-macro-expansion=0" } */
+
+#include "strlenopt.h"
+
+#define NOIPA __attribute__ ((noipa))
+
+#define T(MIN, MAX, SIZE, IDX)						\
+  NOIPA void								\
+  test_ ## MIN ## _ ## MAX ## _ ## SIZE ## _ ## IDX (const char *s)	\
+  {									\
+    size_t len = strlen (s);						\
+    if (MIN <= len && len <= MAX)					\
+      {									\
+	extern char d[];						\
+	strcpy (d, s);							\
+	d[IDX] = 0;							\
+	extern char a ## SIZE[SIZE];					\
+	strcpy (a ## SIZE, d);						\
+      }									\
+  } typedef void dummy_type
+
+
+T (2, 2, 1, 0);
+T (2, 2, 1, 1);     // { dg-warning "writing 2 bytes into a region of size 1" }
+T (2, 2, 1, 2);     // { dg-warning "writing 3 bytes into a region of size 1" }
+
+T (2, 3, 1, 0);
+T (2, 3, 1, 1);     // { dg-warning "writing 2 bytes into a region of size 1" }
+T (2, 3, 1, 2);     // { dg-warning "writing 3 bytes into a region of size 1" "" { xfail *-*-*} }
+T (2, 3, 1, 3);     // { dg-warning "writing 4 bytes into a region of size 1" "" { xfail *-*-* } }
+
+T (5, 7, 3, 1);
+T (5, 7, 3, 2);
+T (5, 7, 3, 3);     // { dg-warning "writing 4 bytes into a region of size 3" }
+T (5, 7, 3, 4);     // { dg-warning "writing 5 bytes into a region of size 3" }
+T (5, 7, 3, 5);     // { dg-warning "writing 6 bytes into a region of size 3" "" { xfail *-*-* } }
diff --git a/gcc/testsuite/gcc.dg/strlenopt-89.c b/gcc/testsuite/gcc.dg/strlenopt-89.c
new file mode 100644
index 0000000..ead451f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/strlenopt-89.c
@@ -0,0 +1,89 @@
+/* PR tree-optimization/92226 - live nul char store to array eliminated
+   { dg-do compile }
+   { dg-options "-O2 -fdump-tree-strlen" } */
+
+#include "strlenopt.h"
+
+#define NOIPA __attribute__ ((noipa))
+
+/* Verify that the nul store  into the destination is only eliminated
+   when overwrites the existing terminating nul added by the strcpy call.
+   Also verify that the second strlen call is eliminated in all cases.  */
+#define T(SIZE, IDX)							\
+  NOIPA void test_ ## SIZE ## _store_nul_ ## IDX (const char *s)	\
+  {									\
+    extern char a ## SIZE[SIZE];					\
+    char *d = a ## SIZE;						\
+    size_t len = SIZE - 1;						\
+    size_t idx = IDX;							\
+    if (strlen (s) == len)						\
+      {									\
+	strcpy (d, s);							\
+	d[idx] = 0;							\
+	if (strlen (d) != idx)						\
+	  abort ();							\
+      }									\
+  } typedef void dummy_type
+
+
+T (1, 0);   // expect nul store to be eliminated
+
+T (2, 0);   // nul store must be retained
+T (2, 1);   // expect nul store to be eliminated
+
+// Same as above but for larger arrays.
+T (3, 0);
+T (3, 1);
+T (3, 2);
+
+T (4, 0);
+T (4, 1);
+T (4, 2);
+T (4, 3);
+
+T (5, 0);
+T (5, 1);
+T (5, 2);
+T (5, 3);
+T (5, 4);
+
+T (6, 0);
+T (6, 1);
+T (6, 2);
+T (6, 3);
+T (6, 4);
+T (6, 5);
+
+T (7, 0);
+T (7, 1);
+T (7, 2);
+T (7, 3);
+T (7, 4);
+T (7, 5);
+T (7, 6);
+
+T (8, 0);
+T (8, 1);
+T (8, 2);
+T (8, 3);
+T (8, 4);
+T (8, 5);
+T (8, 6);
+T (8, 7);
+
+/* Verify that each function makes just one call to strlen to compute
+   the length of its argument (and not also to compute the length of
+   the copy):
+  { dg-final { scan-tree-dump-times "strlen \\(s_" 36 "strlen1" } }
+  { dg-final { scan-tree-dump-not "strlen \\(\\&a" "strlen1" } }
+
+  Verify that nul stores into the last array element have been eliminated
+  (they are preceded by a strcpy storing into all the elements of the array:
+  { dg-final { scan-tree-dump-not "a1\\\] = 0;" "strlen1" } }
+  { dg-final { scan-tree-dump-not "a2 \\\+ 1B\\\] = 0;" "strlen1" } }
+  { dg-final { scan-tree-dump-not "a3 \\\+ 2B\\\] = 0;" "strlen1" } }
+  { dg-final { scan-tree-dump-not "a4 \\\+ 3B\\\] = 0;" "strlen1" } }
+  { dg-final { scan-tree-dump-not "a5 \\\+ 4B\\\] = 0;" "strlen1" } }
+  { dg-final { scan-tree-dump-not "a6 \\\+ 5B\\\] = 0;" "strlen1" } }
+  { dg-final { scan-tree-dump-not "a7 \\\+ 6B\\\] = 0;" "strlen1" } }
+  { dg-final { scan-tree-dump-not "a8 \\\+ 7B\\\] = 0;" "strlen1" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-90.c b/gcc/testsuite/gcc.dg/strlenopt-90.c
new file mode 100644
index 0000000..2d4dad18
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/strlenopt-90.c
@@ -0,0 +1,83 @@
+/* PR tree-optimization/92226 - live nul char store to array eliminated
+   { dg-do compile }
+   { dg-options "-O2 -fdump-tree-strlen" } */
+
+#include "strlenopt.h"
+
+#define NOIPA __attribute__ ((noipa))
+
+#define T(MIN, MAX, SIZE, IDX)						\
+  NOIPA void								\
+  test_ ## MIN ## _ ## MAX ## _ ## SIZE ## _ ## IDX (const char *s)	\
+  {									\
+    extern char a ## SIZE[SIZE];					\
+    char *d = a ## SIZE;						\
+    size_t len = strlen (s);						\
+    size_t idx = IDX;							\
+    if (MIN <= len && len <= MAX)					\
+      {									\
+	strcpy (d, s);							\
+	d[idx] = 0;							\
+	if (strlen (d) != idx)						\
+	  abort ();							\
+      }									\
+  } typedef void dummy_type
+
+
+/* The final nul store must be retained but the second strlen call should
+   be eliminated because the final length of the destination after the nul
+   store must be equal to the index of the store.  */
+T (0, 2, 4, 0);
+
+/* Not handled yet (see below):
+   T (0, 2, 4, 1);  */
+
+/* Not handled yet: in addition to the cases above, the second strlen
+   call can also be eliminated in those below because in both the final
+   length of the destination after the nul store must be in the same
+   range as the length of the source.
+   T (0, 2, 4, 2);
+   T (0, 2, 4, 3);  */
+
+T (2, 3, 4, 0);
+T (2, 3, 4, 1);
+
+/* Not handled yet (see above):
+   T (2, 3, 4, 2);
+   T (2, 3, 4, 3);  */
+
+T (3, 4, 5, 0);
+T (3, 4, 5, 1);
+T (3, 4, 5, 2);
+
+/* Not handled yet (see above):
+   T (3, 4, 5, 3);
+   T (3, 4, 5, 4);  */
+
+T (3, 4, 6, 0);
+T (3, 4, 6, 1);
+T (3, 4, 6, 2);
+
+/* Not handled yet (see above):
+   T (3, 4, 6, 3);
+   T (3, 4, 6, 4);
+   T (3, 4, 6, 5);  */
+
+
+/* Verify that each function makes just one call to strlen to compute
+   the length of its argument (and not also to compute the length of
+   the copy):
+  { dg-final { scan-tree-dump-times "strlen \\(s_" 9 "strlen1" } }
+  { dg-final { scan-tree-dump-not "strlen \\(\\&a" "strlen1" } }
+
+  Verify that nul stores into the destination have not been eliminated:
+  { dg-final { scan-tree-dump-times "a4\\\] = 0;" 2 "strlen1" } }
+  { dg-final { scan-tree-dump-times "a4 \\\+ 1B\\\] = 0;" 1 "strlen1" } }
+
+  { dg-final { scan-tree-dump-times "a5\\\] = 0;" 1 "strlen1" } }
+  { dg-final { scan-tree-dump-times "a5 \\\+ 1B\\\] = 0;" 1 "strlen1" } }
+  { dg-final { scan-tree-dump-times "a5 \\\+ 2B\\\] = 0;" 1 "strlen1" } }
+
+  { dg-final { scan-tree-dump-times "a6\\\] = 0;" 1 "strlen1" } }
+  { dg-final { scan-tree-dump-times "a6 \\\+ 1B\\\] = 0;" 1 "strlen1" } }
+  { dg-final { scan-tree-dump-times "a6 \\\+ 2B\\\] = 0;" 1 "strlen1" } }  */
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index 476bcf6..50cc442 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -281,7 +281,8 @@ get_next_strinfo (strinfo *si)
    *OFFSET_OUT.  */
 
 static int
-get_addr_stridx (tree exp, tree ptr, unsigned HOST_WIDE_INT *offset_out)
+get_addr_stridx (tree exp, tree ptr, unsigned HOST_WIDE_INT *offset_out,
+		 const vr_values *rvals = NULL)
 {
   HOST_WIDE_INT off;
   struct stridxlist *list, *last = NULL;
@@ -319,7 +320,7 @@ get_addr_stridx (tree exp, tree ptr, unsigned HOST_WIDE_INT *offset_out)
       unsigned HOST_WIDE_INT rel_off
 	= (unsigned HOST_WIDE_INT) off - last->offset;
       strinfo *si = get_strinfo (last->idx);
-      if (si && compare_nonzero_chars (si, rel_off) >= 0)
+      if (si && compare_nonzero_chars (si, rel_off, rvals) >= 0)
 	{
 	  if (offset_out)
 	    {
@@ -4328,7 +4329,7 @@ handle_store (gimple_stmt_iterator *gsi, bool *zero_write, const vr_values *rval
     }
   else
     {
-      idx = get_addr_stridx (lhs, NULL_TREE, &offset);
+      idx = get_addr_stridx (lhs, NULL_TREE, &offset, rvals);
       if (idx > 0)
 	si = get_strinfo (idx);
     }