i386: Remove V1DImode shift expanders [PR98287]

On Tue, Feb 02, 2021 at 02:23:55PM +0100, Richard Biener wrote:
> All I say is that the x86 target
> should either not advertise V1DF shifts or advertise the basic
> ops that reasonable simplification would expect to exist.

The backend has several V1?Imode shifts, but optab only for those V1DImode
ones:

grep '[la]sh[lr]v1[qhsdtox]' tmp-mddump.md
(define_insn ("mmx_ashlv1di3")
(define_insn ("mmx_lshrv1di3")
(define_insn ("avx512bw_ashlv1ti3")
(define_insn ("avx512bw_lshrv1ti3")
(define_insn ("sse2_ashlv1ti3")
(define_insn ("sse2_lshrv1ti3")
(define_expand ("ashlv1di3")
(define_expand ("lshrv1di3")
  emit_insn (gen_sse2_lshrv1ti3 (tmp, gen_lowpart (V1TImode, operands[1]),

I think it has been introduced with
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89021#c13

Before we didn't have any V1DImode expanders (except mov/movmisalign, but
those are needed and are supplied for other V1??mode modes too).

This patch just removes the two V1DImode shift expanders with standard names.

2021-02-03  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/98287
	* config/i386/mmx.md (<insn><mode>3): For shifts don't enable expander
	for V1DImode.

	* gcc.dg/pr98287.c: New test.

diff --git a/gcc/config/i386/mmx.md b/gcc/config/i386/mmx.md
index a6ddc710a8464b7844989995658c01a7fc715c10..9e5a4d1f2834b969929049967d1b6b139e0138fd 100644 (file)
--- a/gcc/config/i386/mmx.md
+++ b/gcc/config/i386/mmx.md
@@ -1528,9 +1528,9 @@
    (set_attr "mode" "DI,TI,TI")])
 
 (define_expand "<insn><mode>3"
-  [(set (match_operand:MMXMODE248 0 "register_operand")
-        (any_lshift:MMXMODE248
-         (match_operand:MMXMODE248 1 "register_operand")
+  [(set (match_operand:MMXMODE24 0 "register_operand")
+        (any_lshift:MMXMODE24
+         (match_operand:MMXMODE24 1 "register_operand")
          (match_operand:DI 2 "nonmemory_operand")))]
   "TARGET_MMX_WITH_SSE")
 

diff --git a/gcc/testsuite/gcc.dg/pr98287.c b/gcc/testsuite/gcc.dg/pr98287.c
new file mode 100644 (file)
index 0000000..0314428
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr98287.c
@@ -0,0 +1,19 @@
+/* PR tree-optimization/98287 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-tree-ccp -fno-tree-forwprop -Wno-psabi -w" } */
+
+typedef unsigned long __attribute__((__vector_size__ (8))) V;
+V v;
+
+static __attribute__((noinline, noclone)) V
+bar (unsigned short s)
+{
+  return v >> s << s | v >> s >> 63;
+}
+
+unsigned long
+foo (void)
+{
+  V x = bar (1);
+  return x[0];
+}