[x86] Teach the X86 backend to DAG-combine SSE2 shuffles that are

trivially redundant.

This fixes several cases in the new vector shuffle lowering algorithm
which would generate redundant shuffle instructions for the sake of
simplicity.

I'm also deleting a testcase which was somewhat ridiculous. It was
checking for a bug in 2007 about incorrectly transforming shuffles by
looking for the string "-86" in the output of a pretty substantial
function. This test case doesn't seem to have any value at this point.

Differential Revision: http://reviews.llvm.org/D4240

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211889 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 7 insertions, 42 deletions

diff --git a/test/CodeGen/X86/2007-09-18-ShuffleXformBug.ll b/test/CodeGen/X86/2007-09-18-ShuffleXformBug.ll
deleted file mode 100644
index 0ae1897e60..0000000000
--- a/test/CodeGen/X86/2007-09-18-ShuffleXformBug.ll
+++ /dev/null
@@ -1,30 +0,0 @@
-; RUN: llc < %s -march=x86 -mattr=+sse2 | grep -- -86
-
-define i16 @f(<4 x float>* %tmp116117.i1061.i) nounwind {
-entry:
-	alloca [4 x <4 x float>]		; <[4 x <4 x float>]*>:0 [#uses=167]
-	alloca [4 x <4 x float>]		; <[4 x <4 x float>]*>:1 [#uses=170]
-	alloca [4 x <4 x i32>]		; <[4 x <4 x i32>]*>:2 [#uses=12]
-	%.sub6235.i = getelementptr [4 x <4 x float>]* %0, i32 0, i32 0		; <<4 x float>*> [#uses=76]
-	%.sub.i = getelementptr [4 x <4 x float>]* %1, i32 0, i32 0		; <<4 x float>*> [#uses=59]
-
-	%tmp124.i1062.i = getelementptr <4 x float>* %tmp116117.i1061.i, i32 63		; <<4 x float>*> [#uses=1]
-	%tmp125.i1063.i = load <4 x float>* %tmp124.i1062.i		; <<4 x float>> [#uses=5]
-	%tmp828.i1077.i = shufflevector <4 x float> %tmp125.i1063.i, <4 x float> undef, <4 x i32> < i32 1, i32 1, i32 1, i32 1 >		; <<4 x float>> [#uses=4]
-	%tmp704.i1085.i = load <4 x float>* %.sub6235.i		; <<4 x float>> [#uses=1]
-	%tmp712.i1086.i = call <4 x float> @llvm.x86.sse.max.ps( <4 x float> %tmp704.i1085.i, <4 x float> %tmp828.i1077.i )		; <<4 x float>> [#uses=1]
-	store <4 x float> %tmp712.i1086.i, <4 x float>* %.sub.i
-
-	%tmp2587.i1145.gep.i = getelementptr [4 x <4 x float>]* %1, i32 0, i32 0, i32 2		; <float*> [#uses=1]
-	%tmp5334.i = load float* %tmp2587.i1145.gep.i		; <float> [#uses=5]
-	%tmp2723.i1170.i = insertelement <4 x float> undef, float %tmp5334.i, i32 2		; <<4 x float>> [#uses=5]
-	store <4 x float> %tmp2723.i1170.i, <4 x float>* %.sub6235.i
-
-	%tmp1406.i1367.i = shufflevector <4 x float> %tmp2723.i1170.i, <4 x float> undef, <4 x i32> < i32 2, i32 2, i32 2, i32 2 >		; <<4 x float>> [#uses=1]
-	%tmp84.i1413.i = load <4 x float>* %.sub6235.i		; <<4 x float>> [#uses=1]
-	%tmp89.i1415.i = fmul <4 x float> %tmp84.i1413.i, %tmp1406.i1367.i		; <<4 x float>> [#uses=1]
-	store <4 x float> %tmp89.i1415.i, <4 x float>* %.sub.i
-        ret i16 0
-}
-
-declare <4 x float> @llvm.x86.sse.max.ps(<4 x float>, <4 x float>)
diff --git a/test/CodeGen/X86/vector-shuffle-128-v8.ll b/test/CodeGen/X86/vector-shuffle-128-v8.ll
index 7447fdc874..091822b6cb 100644
--- a/test/CodeGen/X86/vector-shuffle-128-v8.ll
+++ b/test/CodeGen/X86/vector-shuffle-128-v8.ll
@@ -51,7 +51,7 @@ define <8 x i16> @shuffle_v8i16_31206745(<8 x i16> %a, <8 x i16> %b) {
 ; CHECK-SSE2-LABEL: @shuffle_v8i16_31206745
 ; CHECK-SSE2:       # BB#0:
 ; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm0[3,1,2,0,4,5,6,7]
-; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,7,4,5]
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,1,3,2]
 ; CHECK-SSE2-NEXT:    retq
   %shuffle = shufflevector <8 x i16> %a, <8 x i16> %b, <8 x i32> <i32 3, i32 1, i32 2, i32 0, i32 6, i32 7, i32 4, i32 5>
   ret <8 x i16> %shuffle
@@ -159,7 +159,7 @@ define <8 x i16> @shuffle_v8i16_26401375(<8 x i16> %a, <8 x i16> %b) {
 ; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,7,5,4,6]
 ; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,3,2,1]
 ; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm0[1,3,2,0,4,5,6,7]
-; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,7,4,5]
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,1,3,2]
 ; CHECK-SSE2-NEXT:    retq
   %shuffle = shufflevector <8 x i16> %a, <8 x i16> %b, <8 x i32> <i32 2, i32 6, i32 4, i32 0, i32 1, i32 3, i32 7, i32 5>
   ret <8 x i16> %shuffle
@@ -273,8 +273,7 @@ define <8 x i16> @shuffle_v8i16_4563XXXX(<8 x i16> %a, <8 x i16> %b) {
 ; CHECK-SSE2:       # BB#0:
 ; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[3,1,2,0]
 ; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm0[0,3,2,3,4,5,6,7]
-; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,2,2,3]
-; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm0[2,3,0,1,4,5,6,7]
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[2,0,2,3]
 ; CHECK-SSE2-NEXT:    retq
   %shuffle = shufflevector <8 x i16> %a, <8 x i16> %b, <8 x i32> <i32 4, i32 5, i32 6, i32 3, i32 undef, i32 undef, i32 undef, i32 undef>
   ret <8 x i16> %shuffle
@@ -285,8 +284,7 @@ define <8 x i16> @shuffle_v8i16_01274563(<8 x i16> %a, <8 x i16> %b) {
 ; CHECK-SSE2:       # BB#0:
 ; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,2,1,3]
 ; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,5,4,7]
-; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,3,2,1]
-; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,7,4,5]
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,3,1,2]
 ; CHECK-SSE2-NEXT:    retq
   %shuffle = shufflevector <8 x i16> %a, <8 x i16> %b, <8 x i32> <i32 0, i32 1, i32 2, i32 7, i32 4, i32 5, i32 6, i32 3>
   ret <8 x i16> %shuffle
@@ -297,8 +295,7 @@ define <8 x i16> @shuffle_v8i16_45630127(<8 x i16> %a, <8 x i16> %b) {
 ; CHECK-SSE2:       # BB#0:
 ; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[3,1,2,0]
 ; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm0[0,3,1,2,4,5,6,7]
-; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,2,1,3]
-; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm0[2,3,0,1,4,5,6,7]
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[2,0,1,3]
 ; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,7,5,4]
 ; CHECK-SSE2-NEXT:    retq
   %shuffle = shufflevector <8 x i16> %a, <8 x i16> %b, <8 x i32> <i32 4, i32 5, i32 6, i32 3, i32 0, i32 1, i32 2, i32 7>
@@ -359,9 +356,8 @@ define <8 x i16> @shuffle_v8i16_08196e7f(<8 x i16> %a, <8 x i16> %b) {
 define <8 x i16> @shuffle_v8i16_0c1d6879(<8 x i16> %a, <8 x i16> %b) {
 ; CHECK-SSE2-LABEL: @shuffle_v8i16_0c1d6879
 ; CHECK-SSE2:       # BB#0:
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm1 = xmm1[2,0,2,3]
 ; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,3,2,3]
-; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm1 = xmm1[0,2,2,3]
-; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm1 = xmm1[2,3,0,1,4,5,6,7]
 ; CHECK-SSE2-NEXT:    punpcklwd %xmm1, %xmm0
 ; CHECK-SSE2-NEXT:    retq
   %shuffle = shufflevector <8 x i16> %a, <8 x i16> %b, <8 x i32> <i32 0, i32 12, i32 1, i32 13, i32 6, i32 8, i32 7, i32 9>
@@ -458,8 +454,7 @@ define <8 x i16> @shuffle_v8i16_XXXXcde3(<8 x i16> %a, <8 x i16> %b) {
 ; CHECK-SSE2-NEXT:    punpckhwd %xmm0, %xmm1
 ; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm1[0,2,2,3,4,5,6,7]
 ; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,4,7,6,7]
-; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,1,2,0]
-; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,7,4,5]
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,1,0,2]
 ; CHECK-SSE2-NEXT:    retq
   %shuffle = shufflevector <8 x i16> %a, <8 x i16> %b, <8 x i32> <i32 undef, i32 undef, i32 undef, i32 undef, i32 12, i32 13, i32 14, i32 3>
   ret <8 x i16> %shuffle