SelectionDAG: Aggressively fold shuffles of constant splats.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207352 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 3f68d49da68191409bfb7d135bbc98ad3b9077f7..46d0fcac41003a524c97ad143cb553644092b9c9 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1441,6 +1441,11 @@ SDValue SelectionDAG::getVectorShuffle(EVT VT, SDLoc dl, SDValue N1,
   if (Identity && NElts)
     return N1;
 
+  // Shuffling a constant splat doesn't change the result.
+  if (N2Undef && N1.getOpcode() == ISD::BUILD_VECTOR)
+    if (cast<BuildVectorSDNode>(N1)->getConstantSplatValue())
+      return N1;
+
   FoldingSetNodeID ID;
   SDValue Ops[2] = { N1, N2 };
   AddNodeIDNode(ID, ISD::VECTOR_SHUFFLE, getVTList(VT), Ops, 2);

diff --git a/test/CodeGen/X86/vector-idiv.ll b/test/CodeGen/X86/vector-idiv.ll
index 3b300f74061784684e52559cfb8c9b3f4e4cd01e..981c317157f1a26b9d53433c0330f37a6cbeed3e 100644 (file)
--- a/test/CodeGen/X86/vector-idiv.ll
+++ b/test/CodeGen/X86/vector-idiv.ll
@@ -115,6 +115,7 @@ define <4 x i32> @test8(<4 x i32> %a) {
 ; SSE-LABEL: test8:
 ; SSE: pmuldq
 ; SSE: pshufd  $57
+; SSE-NOT: pshufd      $57
 ; SSE: pmuldq
 ; SSE: shufps  $-35
 ; SSE: pshufd  $-40
@@ -126,6 +127,7 @@ define <4 x i32> @test8(<4 x i32> %a) {
 ; AVX-LABEL: test8:
 ; AVX: vpmuldq
 ; AVX: vpshufd $57
+; AVX-NOT: vpshufd     $57
 ; AVX: vpmuldq
 ; AVX: vshufps $-35
 ; AVX: vpshufd $-40
@@ -140,7 +142,7 @@ define <8 x i32> @test9(<8 x i32> %a) {
   ret <8 x i32> %div
 
 ; AVX-LABEL: test9:
-; AVX: vpermd
+; AVX: vpbroadcastd
 ; AVX: vpmuldq
 ; AVX: vshufps $-35
 ; AVX: vpmuldq
@@ -157,7 +159,7 @@ define <8 x i32> @test10(<8 x i32> %a) {
   ret <8 x i32> %rem
 
 ; AVX-LABEL: test10:
-; AVX: vpermd
+; AVX: vpbroadcastd
 ; AVX: vpmuludq
 ; AVX: vshufps $-35
 ; AVX: vpmuludq
@@ -174,7 +176,7 @@ define <8 x i32> @test11(<8 x i32> %a) {
   ret <8 x i32> %rem
 
 ; AVX-LABEL: test11:
-; AVX: vpermd
+; AVX: vpbroadcastd
 ; AVX: vpmuldq
 ; AVX: vshufps $-35
 ; AVX: vpmuldq