Eliminate redundant vec_select moves.

gcc/
        * rtlanal.c (set_noop_p): Return nonzero in case of redundant vec_select for
        overlapping register lanes.

testsuite/
        * config/gcc.dg/vect/vect-nop-move.c: New.

From-SVN: r205712

4 files changed, 94 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7488e92..49c0844 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2013-12-05  Tejas Belagod  <tejas.belagod@arm.com>
+
+	* rtlanal.c (set_noop_p): Return nonzero in case of redundant vec_select
+	for overlapping register lanes.
+
 2013-12-05  Kirill Yukhin  <kirill.yukhin@intel.com>
 
 	* config/i386/i386.c (ix86_expand_builtin): Generate
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 0cd0c7e..38f9e36 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -1180,6 +1180,27 @@ set_noop_p (const_rtx set)
       dst = SUBREG_REG (dst);
     }
 
+  /* It is a NOOP if destination overlaps with selected src vector
+     elements.  */
+  if (GET_CODE (src) == VEC_SELECT
+      && REG_P (XEXP (src, 0)) && REG_P (dst)
+      && HARD_REGISTER_P (XEXP (src, 0))
+      && HARD_REGISTER_P (dst))
+    {
+      int i;
+      rtx par = XEXP (src, 1);
+      rtx src0 = XEXP (src, 0);
+      int c0 = INTVAL (XVECEXP (par, 0, 0));
+      HOST_WIDE_INT offset = GET_MODE_UNIT_SIZE (GET_MODE (src0)) * c0;
+
+      for (i = 1; i < XVECLEN (par, 0); i++)
+	if (INTVAL (XVECEXP (par, 0, i)) != c0 + i)
+	  return 0;
+      return
+	simplify_subreg_regno (REGNO (src0), GET_MODE (src0),
+			       offset, GET_MODE (dst)) == (int) REGNO (dst);
+    }
+
   return (REG_P (src) && REG_P (dst)
 	  && REGNO (src) == REGNO (dst));
 }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 2ede528..d9f7de3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2013-12-05  Tejas Belagod  <tejas.belagod@arm.com>
+
+	* gcc.dg/vect/vect-nop-move.c: New test.
+
 2013-12-05  Max Ostapenko  <m.ostapenko@partner.samsung.com>
 
 	* c-c++-common/tsan/atomic_stack.c: New test.
diff --git a/gcc/testsuite/gcc.dg/vect/vect-nop-move.c b/gcc/testsuite/gcc.dg/vect/vect-nop-move.c
new file mode 100644
index 0000000..19419335
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-nop-move.c
@@ -0,0 +1,64 @@
+/* { dg-do run } */ 
+/* { dg-require-effective-target vect_float } */
+/* { dg-options "-O3 -fdump-rtl-combine-details" } */
+
+extern void abort (void);
+
+#define NOINLINE __attribute__((noinline))
+
+typedef float float32x4_t __attribute__ ((__vector_size__ (16)));
+typedef float float32x2_t __attribute__ ((__vector_size__ (8)));
+
+NOINLINE float
+foo32x4_be (float32x4_t x)
+{
+  return x[3];
+}
+
+NOINLINE float
+foo32x4_le (float32x4_t x)
+{
+  return x[0];
+}
+
+NOINLINE float
+bar (float a)
+{
+  return a;
+}
+
+NOINLINE float
+foo32x2_be (float32x2_t x)
+{
+  return bar (x[1]);
+}
+
+NOINLINE float
+foo32x2_le (float32x2_t x)
+{
+  return bar (x[0]);
+}
+
+int
+main()
+{
+  float32x4_t a = { 0.0f, 1.0f, 2.0f, 3.0f };
+  float32x2_t b = { 0.0f, 1.0f };
+
+  if (foo32x4_be (a) != 3.0f)
+    abort ();
+
+  if (foo32x4_le (a) != 0.0f)
+    abort ();
+
+  if (foo32x2_be (b) != 1.0f)
+    abort ();
+
+  if (foo32x2_le (b) != 0.0f)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-rtl-dump "deleting noop move" "combine" { target aarch64*-*-* } } } */
+/* { dg-final { cleanup-rtl-dump "combine" } } */