i386: Fix vph{add,subs?}[wd] 256-bit AVX2 RTL patterns [PR94460]

The following testcase is miscompiled, because the AVX2 patterns don't
describe correctly what the insn does.  E.g. vphaddd with %ymm* operands
(the second pattern) instruction as per:
https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm256_hadd_epi32&expand=2941
does { a0+a1, a2+a3, b0+b1, b2+b3, a4+a5, a6+a7, b4+b5, b6+b7 }
but our RTL pattern did
     { a0+a1, a2+a3, a4+a5, a6+a7, b0+b1, b2+b3, b4+b5, b6+b7 }
where the first and last 64 bits are the same and two middle 64 bits
swapped.
https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm256_hadd_epi16&expand=2939
similarly, insn does:
     { a0+a1, a2+a3, a4+a5, a6+a7, b0+b1, b2+b3, b4+b5, b6+b7,
       a8+a9, a10+a11, a12+a13, a14+a15, b8+b9, b10+b11, b12+b13, b14+b15 }
but RTL pattern did
     { a0+a1, a2+a3, a4+a5, a6+a7, a8+a9, a10+a11, a12+a13, a14+a15,
       b0+b1, b2+b3, b4+b5, b6+b7, b8+b9, b10+b11, b12+b13, b14+b15 }
again, first and last 64 bits are the same and the two middle 64 bits
swapped.

2020-04-03  Jakub Jelinek  <jakub@redhat.com>

	PR target/94460
	* config/i386/sse.md (avx2_ph<plusminus_mnemonic>wv16hi3,
	avx2_ph<plusminus_mnemonic>dv8si3): Fix up RTL pattern to do
	second half of first lane from first lane of second operand and
	first half of second lane from second lane of first operand.

	* gcc.target/i386/avx2-pr94460.c: New test.

4 files changed, 72 insertions, 26 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4cb05e922e9..022d71e9e73 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,16 @@
 2020-04-07  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2020-04-03  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/94460
+	* config/i386/sse.md (avx2_ph<plusminus_mnemonic>wv16hi3,
+	avx2_ph<plusminus_mnemonic>dv8si3): Fix up RTL pattern to do
+	second half of first lane from first lane of second operand and
+	first half of second lane from second lane of first operand.
+
+2020-04-07  Jakub Jelinek  <jakub@redhat.com>
+
 	2020-04-01  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/94423
diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index a8b879bcdc4..618fc231c40 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -15543,22 +15543,6 @@
 	    (vec_concat:V4HI
 	      (vec_concat:V2HI
 		(ssse3_plusminus:HI
-		  (vec_select:HI (match_dup 1) (parallel [(const_int 8)]))
-		  (vec_select:HI (match_dup 1) (parallel [(const_int 9)])))
-		(ssse3_plusminus:HI
-		  (vec_select:HI (match_dup 1) (parallel [(const_int 10)]))
-		  (vec_select:HI (match_dup 1) (parallel [(const_int 11)]))))
-	      (vec_concat:V2HI
-		(ssse3_plusminus:HI
-		  (vec_select:HI (match_dup 1) (parallel [(const_int 12)]))
-		  (vec_select:HI (match_dup 1) (parallel [(const_int 13)])))
-		(ssse3_plusminus:HI
-		  (vec_select:HI (match_dup 1) (parallel [(const_int 14)]))
-		  (vec_select:HI (match_dup 1) (parallel [(const_int 15)]))))))
-	  (vec_concat:V8HI
-	    (vec_concat:V4HI
-	      (vec_concat:V2HI
-		(ssse3_plusminus:HI
 		  (vec_select:HI
 		    (match_operand:V16HI 2 "nonimmediate_operand" "xm")
 		    (parallel [(const_int 0)]))
@@ -15572,7 +15556,23 @@
 		  (vec_select:HI (match_dup 2) (parallel [(const_int 5)])))
 		(ssse3_plusminus:HI
 		  (vec_select:HI (match_dup 2) (parallel [(const_int 6)]))
-		  (vec_select:HI (match_dup 2) (parallel [(const_int 7)])))))
+		  (vec_select:HI (match_dup 2) (parallel [(const_int 7)]))))))
+	  (vec_concat:V8HI
+	    (vec_concat:V4HI
+	      (vec_concat:V2HI
+		(ssse3_plusminus:HI
+		  (vec_select:HI (match_dup 1) (parallel [(const_int 8)]))
+		  (vec_select:HI (match_dup 1) (parallel [(const_int 9)])))
+		(ssse3_plusminus:HI
+		  (vec_select:HI (match_dup 1) (parallel [(const_int 10)]))
+		  (vec_select:HI (match_dup 1) (parallel [(const_int 11)]))))
+	      (vec_concat:V2HI
+		(ssse3_plusminus:HI
+		  (vec_select:HI (match_dup 1) (parallel [(const_int 12)]))
+		  (vec_select:HI (match_dup 1) (parallel [(const_int 13)])))
+		(ssse3_plusminus:HI
+		  (vec_select:HI (match_dup 1) (parallel [(const_int 14)]))
+		  (vec_select:HI (match_dup 1) (parallel [(const_int 15)])))))
 	    (vec_concat:V4HI
 	      (vec_concat:V2HI
 		(ssse3_plusminus:HI
@@ -15688,21 +15688,21 @@
 		(vec_select:SI (match_dup 1) (parallel [(const_int 3)]))))
 	    (vec_concat:V2SI
 	      (plusminus:SI
-		(vec_select:SI (match_dup 1) (parallel [(const_int 4)]))
-		(vec_select:SI (match_dup 1) (parallel [(const_int 5)])))
-	      (plusminus:SI
-		(vec_select:SI (match_dup 1) (parallel [(const_int 6)]))
-		(vec_select:SI (match_dup 1) (parallel [(const_int 7)])))))
-	  (vec_concat:V4SI
-	    (vec_concat:V2SI
-	      (plusminus:SI
 		(vec_select:SI
 		  (match_operand:V8SI 2 "nonimmediate_operand" "xm")
 		  (parallel [(const_int 0)]))
 		(vec_select:SI (match_dup 2) (parallel [(const_int 1)])))
 	      (plusminus:SI
 		(vec_select:SI (match_dup 2) (parallel [(const_int 2)]))
-		(vec_select:SI (match_dup 2) (parallel [(const_int 3)]))))
+		(vec_select:SI (match_dup 2) (parallel [(const_int 3)])))))
+	  (vec_concat:V4SI
+	    (vec_concat:V2SI
+	      (plusminus:SI
+		(vec_select:SI (match_dup 1) (parallel [(const_int 4)]))
+		(vec_select:SI (match_dup 1) (parallel [(const_int 5)])))
+	      (plusminus:SI
+		(vec_select:SI (match_dup 1) (parallel [(const_int 6)]))
+		(vec_select:SI (match_dup 1) (parallel [(const_int 7)]))))
 	    (vec_concat:V2SI
 	      (plusminus:SI
 		(vec_select:SI (match_dup 2) (parallel [(const_int 4)]))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 78f4b5119d8..963a1af39be 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,11 @@
 2020-04-07  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2020-04-03  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/94460
+	* gcc.target/i386/avx2-pr94460.c: New test.
+
 	2020-04-01  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/94423
diff --git a/gcc/testsuite/gcc.target/i386/avx2-pr94460.c b/gcc/testsuite/gcc.target/i386/avx2-pr94460.c
new file mode 100644
index 00000000000..75b7a7bf313
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/avx2-pr94460.c
@@ -0,0 +1,31 @@
+/* PR target/94460 */
+/* { dg-do run { target { avx2 && int128 } } } */
+/* { dg-options "-O2 -mavx2" } */
+
+#include <x86intrin.h>
+#include "avx2-check.h"
+
+typedef __int128 v2ti __attribute__ ((__vector_size__ (32)));
+
+static inline v2ti
+foo (__v16hi b)
+{
+  return (v2ti) _mm256_hsub_epi16 ((__m256i) b, (__m256i) b);
+}
+
+static inline v2ti
+bar (__v8si b)
+{
+  return (v2ti) _mm256_hsub_epi32 ((__m256i) b, (__m256i) b);
+}
+
+static void
+avx2_test (void)
+{
+  v2ti x = foo ((__v16hi) { 1 });
+  if (x[0] != ((__int128)1 << 64 | 1) || x[1] != 0)
+    abort ();
+  x = bar ((__v8si) { 1 });
+  if (x[0] != ((__int128)1 << 64 | 1) || x[1] != 0)
+    abort ();
+}