[PATCH] Fix *vec_duplicate_p (PR rtl-optimization/83682)

[Richard Biener]

On January 5, 2018 11:05:59 PM GMT+01:00, Jakub Jelinek <jakub@redhat.com> wrote:
>Hi!
>
>All the vec_duplicate_p uses in simplify-rtx.c assume that it returns
>vector
>element if it returns true, and while that is the case for CONST_VECTOR
>which can't contain anything but scalars, VEC_DUPLICATE is documented:
>"This operation converts a scalar into a vector or a small vector into
>a
>larger one by duplicating the input values.  The output vector mode
>must have
>the same submodes as the input vector mode or the scalar modes, and the
>number of output parts must be an integer multiple of the number of
>input
>parts." and e.g. on x86 that is heavily used in the backend.
>So, simplify-rtx.c checks something and expects to be given a scalar
>element, but it can return something different with a different
>(vector)
>mode instead.
>
>Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok
>for
>trunk?

OK. 

Richard. 

>2018-01-05  Jakub Jelinek  <jakub@redhat.com>
>
>	PR rtl-optimization/83682
>	* rtl.h (const_vec_duplicate_p): Only return true for VEC_DUPLICATE
>	if it has non-VECTOR_MODE element mode.
>	(vec_duplicate_p): Likewise.
>
>	* gcc.target/i386/pr83682.c: New test.
>
>--- gcc/rtl.h.jj	2018-01-04 00:43:14.704702340 +0100
>+++ gcc/rtl.h	2018-01-05 16:03:52.420823342 +0100
>@@ -2969,7 +2969,9 @@ const_vec_duplicate_p (T x, T *elt)
>       *elt = CONST_VECTOR_ENCODED_ELT (x, 0);
>       return true;
>     }
>-  if (GET_CODE (x) == CONST && GET_CODE (XEXP (x, 0)) ==
>VEC_DUPLICATE)
>+  if (GET_CODE (x) == CONST
>+      && GET_CODE (XEXP (x, 0)) == VEC_DUPLICATE
>+      && !VECTOR_MODE_P (GET_MODE (XEXP (XEXP (x, 0), 0))))
>     {
>       *elt = XEXP (XEXP (x, 0), 0);
>       return true;
>@@ -2984,7 +2986,8 @@ template <typename T>
> inline bool
> vec_duplicate_p (T x, T *elt)
> {
>-  if (GET_CODE (x) == VEC_DUPLICATE)
>+  if (GET_CODE (x) == VEC_DUPLICATE
>+      && !VECTOR_MODE_P (GET_MODE (XEXP (x, 0))))
>     {
>       *elt = XEXP (x, 0);
>       return true;
>--- gcc/testsuite/gcc.target/i386/pr83682.c.jj	2018-01-05
>16:06:57.299885887 +0100
>+++ gcc/testsuite/gcc.target/i386/pr83682.c	2018-01-05
>16:06:26.630875486 +0100
>@@ -0,0 +1,17 @@
>+/* PR rtl-optimization/83682 */
>+/* { dg-do compile } */
>+/* { dg-options "-O2 -msse2" } */
>+
>+typedef float V __attribute__((__vector_size__(16)));
>+typedef double W __attribute__((__vector_size__(16)));
>+V b;
>+W c;
>+
>+void
>+foo (void *p)
>+{
>+  V e = __builtin_ia32_cvtsd2ss (b, c);
>+  V g = e;
>+  float f = g[0];
>+  __builtin_memcpy (p, &f, sizeof (f));
>+}
>
>	Jakub