re PR middle-end/61762 (failure to optimize memcpy from constant string)

2014-07-25  Richard Biener  <rguenther@suse.de>

	PR middle-end/61762
	PR middle-end/61894
	* fold-const.c (native_encode_int): Add and handle offset
	parameter to do partial encodings of expr.
	(native_encode_fixed): Likewise.
	(native_encode_real): Likewise.
	(native_encode_complex): Likewise.
	(native_encode_vector): Likewise.
	(native_encode_string): Likewise.
	(native_encode_expr): Likewise.
	* fold-const.c (native_encode_expr): Add offset parameter
	defaulting to -1.
	* gimple-fold.c (fold_string_cst_ctor_reference): Remove.
	(fold_ctor_reference): Handle all reads from tcc_constant
	ctors.

	* gcc.dg/pr61762.c: New testcase.
	* gcc.dg/fold-cstring.c: Likewise.
	* gcc.dg/fold-cvect.c: Likewise.

From-SVN: r213045

4 files changed, 109 insertions, 0 deletions

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 17daa07..72ba8a7 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2014-07-25  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/61762
+	PR middle-end/61894
+	* gcc.dg/pr61762.c: New testcase.
+	* gcc.dg/fold-cstring.c: Likewise.
+	* gcc.dg/fold-cvect.c: Likewise.
+
 2014-07-24  Ulrich Weigand  <Ulrich.Weigand@de.ibm.com>
 
 	* gcc.target/powerpc/ppc64-abi-warn-3.c: New test.
diff --git a/gcc/testsuite/gcc.dg/fold-cstring.c b/gcc/testsuite/gcc.dg/fold-cstring.c
new file mode 100644
index 0000000..f92b120
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-cstring.c
@@ -0,0 +1,44 @@
+/* { dg-do run } */
+/* { dg-options "-O" } */
+
+/* The following are testcases for native_interpret_int,
+   native_interpret_complex and native_interpret_vector decoding
+   pieces of a string constant encoded by native_encode_string.  */
+
+extern void abort (void);
+
+/* We should fold all reads from xconstant and eliminate it, removing
+   the reference to blah which cannot be resolved at link time.  */
+extern int blah;
+
+static const struct {
+    int *y;
+    const char x[32] __attribute__((aligned(32)));
+} xconstant = { &blah, "01234567899876543210123456789000" };
+
+typedef int v4si __attribute__((vector_size(16)));
+
+int main()
+{
+  if (sizeof (int) != 4)
+    return 0;
+  if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
+    {
+      if (*(int *)&xconstant.x[4] != 0x34353637)
+	abort ();
+      if ((*(v4si *)&xconstant.x[16])[1] != 0x31323334)
+	abort ();
+      if (__imag (*(_Complex int *)&xconstant.x[8]) != 0x37363534)
+	abort ();
+    }
+  else if (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
+    {
+      if (*(int *)&xconstant.x[4] != 0x37363534)
+	abort ();
+      if ((*(v4si *)&xconstant.x[16])[1] != 0x34333231)
+	abort ();
+      if (__imag (*(_Complex int *)&xconstant.x[8]) != 0x34353637)
+	abort ();
+    }
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/fold-cvect.c b/gcc/testsuite/gcc.dg/fold-cvect.c
new file mode 100644
index 0000000..8687f8d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-cvect.c
@@ -0,0 +1,38 @@
+/* { dg-do run } */
+/* { dg-options "-O" } */
+
+extern void abort (void);
+
+/* We should fold all reads from xconstant and eliminate it, removing
+   the reference to blah which cannot be resolved at link time.  */
+extern int blah;
+
+typedef int v4si __attribute__((vector_size(16)));
+
+static const struct {
+    int *y;
+    const v4si x[2] __attribute__((aligned(32)));
+} xconstant = { &blah, { { 0, 1, 2, 3 }, { 2, 3, 4, 5 } } };
+
+int main()
+{
+  if (sizeof (int) != 4)
+    return 0;
+  if (*(int *)&xconstant.x[0][0] != 0)
+    abort ();
+  if (*(int *)&xconstant.x[0][1] != 1)
+    abort ();
+  if (*(int *)&xconstant.x[0][2] != 2)
+    abort ();
+  if (*(int *)&xconstant.x[0][3] != 3)
+    abort ();
+  if (*(int *)&xconstant.x[1][0] != 2)
+    abort ();
+  if (*(int *)&xconstant.x[1][1] != 3)
+    abort ();
+  if (*(int *)&xconstant.x[1][2] != 4)
+    abort ();
+  if (*(int *)&xconstant.x[1][3] != 5)
+    abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/pr61762.c b/gcc/testsuite/gcc.dg/pr61762.c
new file mode 100644
index 0000000..5abe534
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr61762.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-release_ssa" } */
+
+unsigned int f()
+{
+  static const char string[] = "Private";
+
+  unsigned int priv;
+  __builtin_memcpy(&priv, &string[0], sizeof(priv));
+  return priv;
+}
+
+/* We should have removed the static string and simplified the
+   memcpy to a store from an integer constant.  CCP
+   already performs the simplification but only after release_ssa
+   the unused local static is removed.  */
+
+/* { dg-final { scan-tree-dump-not "Private" "release_ssa" } } */
+/* { dg-final { cleanup-tree-dump "release_ssa" } } */