SelectionDAG: Teach FoldConstantArithmetic how to deal with vectors.

This required disabling a PowerPC optimization that did the following:
input:
x = BUILD_VECTOR <i32 16, i32 16, i32 16, i32 16>
lowered to:
tmp = BUILD_VECTOR <i32 8, i32 8, i32 8, i32 8>
x = ADD tmp, tmp

The add now gets folded immediately and we're back at the BUILD_VECTOR we
started from. I don't see a way to fix this currently so I left it disabled
for now.

Fix some trivially foldable X86 tests too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174325 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 129 insertions, 55 deletions

diff --git a/include/llvm/CodeGen/SelectionDAG.h b/include/llvm/CodeGen/SelectionDAG.h
index 69bc3bb57f..c25497aa97 100644
--- a/include/llvm/CodeGen/SelectionDAG.h
+++ b/include/llvm/CodeGen/SelectionDAG.h
@@ -992,10 +992,8 @@ public:
   SDValue CreateStackTemporary(EVT VT1, EVT VT2);
 
   /// FoldConstantArithmetic -
-  SDValue FoldConstantArithmetic(unsigned Opcode,
-                                 EVT VT,
-                                 ConstantSDNode *Cst1,
-                                 ConstantSDNode *Cst2);
+  SDValue FoldConstantArithmetic(unsigned Opcode, EVT VT,
+                                 SDNode *Cst1, SDNode *Cst2);
 
   /// FoldSetCC - Constant fold a setcc to true or false.
   SDValue FoldSetCC(EVT VT, SDValue N1,
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 57241227d9..09885d8dea 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2680,44 +2680,117 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL,
   return SDValue(N, 0);
 }
 
-SDValue SelectionDAG::FoldConstantArithmetic(unsigned Opcode,
-                                             EVT VT,
-                                             ConstantSDNode *Cst1,
-                                             ConstantSDNode *Cst2) {
-  const APInt &C1 = Cst1->getAPIntValue(), &C2 = Cst2->getAPIntValue();
+SDValue SelectionDAG::FoldConstantArithmetic(unsigned Opcode, EVT VT,
+                                             SDNode *Cst1, SDNode *Cst2) {
+  SmallVector<std::pair<ConstantSDNode *, ConstantSDNode *>, 4> Inputs;
+  SmallVector<SDValue, 4> Outputs;
+  EVT SVT = VT.getScalarType();
+
+  ConstantSDNode *Scalar1 = dyn_cast<ConstantSDNode>(Cst1);
+  ConstantSDNode *Scalar2 = dyn_cast<ConstantSDNode>(Cst2);
+  if (Scalar1 && Scalar2) {
+    // Scalar instruction.
+    Inputs.push_back(std::make_pair(Scalar1, Scalar2));
+  } else {
+    // For vectors extract each constant element into Inputs so we can constant
+    // fold them individually.
+    BuildVectorSDNode *BV1 = dyn_cast<BuildVectorSDNode>(Cst1);
+    BuildVectorSDNode *BV2 = dyn_cast<BuildVectorSDNode>(Cst2);
+    if (!BV1 || !BV2)
+      return SDValue();
+
+    assert(BV1->getNumOperands() == BV2->getNumOperands() && "Out of sync!");
+
+    for (unsigned I = 0, E = BV1->getNumOperands(); I != E; ++I) {
+      ConstantSDNode *V1 = dyn_cast<ConstantSDNode>(BV1->getOperand(I));
+      ConstantSDNode *V2 = dyn_cast<ConstantSDNode>(BV2->getOperand(I));
+      if (!V1 || !V2) // Not a constant, bail.
+        return SDValue();
+
+      // Avoid BUILD_VECTOR nodes that perform implicit truncation.
+      // FIXME: This is valid and could be handled by truncating the APInts.
+      if (V1->getValueType(0) != SVT || V2->getValueType(0) != SVT)
+        return SDValue();
+
+      Inputs.push_back(std::make_pair(V1, V2));
+    }
+  }
 
-  switch (Opcode) {
-  case ISD::ADD:  return getConstant(C1 + C2, VT);
-  case ISD::SUB:  return getConstant(C1 - C2, VT);
-  case ISD::MUL:  return getConstant(C1 * C2, VT);
-  case ISD::UDIV:
-    if (C2.getBoolValue()) return getConstant(C1.udiv(C2), VT);
-    break;
-  case ISD::UREM:
-    if (C2.getBoolValue()) return getConstant(C1.urem(C2), VT);
-    break;
-  case ISD::SDIV:
-    if (C2.getBoolValue()) return getConstant(C1.sdiv(C2), VT);
-    break;
-  case ISD::SREM:
-    if (C2.getBoolValue()) return getConstant(C1.srem(C2), VT);
-    break;
-  case ISD::AND:  return getConstant(C1 & C2, VT);
-  case ISD::OR:   return getConstant(C1 | C2, VT);
-  case ISD::XOR:  return getConstant(C1 ^ C2, VT);
-  case ISD::SHL:  return getConstant(C1 << C2, VT);
-  case ISD::SRL:  return getConstant(C1.lshr(C2), VT);
-  case ISD::SRA:  return getConstant(C1.ashr(C2), VT);
-  case ISD::ROTL: return getConstant(C1.rotl(C2), VT);
-  case ISD::ROTR: return getConstant(C1.rotr(C2), VT);
-  default: break;
+  // We have a number of constant values, constant fold them element by element.
+  for (unsigned I = 0, E = Inputs.size(); I != E; ++I) {
+    const APInt &C1 = Inputs[I].first->getAPIntValue();
+    const APInt &C2 = Inputs[I].second->getAPIntValue();
+
+    switch (Opcode) {
+    case ISD::ADD:
+      Outputs.push_back(getConstant(C1 + C2, SVT));
+      break;
+    case ISD::SUB:
+      Outputs.push_back(getConstant(C1 - C2, SVT));
+      break;
+    case ISD::MUL:
+      Outputs.push_back(getConstant(C1 * C2, SVT));
+      break;
+    case ISD::UDIV:
+      if (!C2.getBoolValue())
+        return SDValue();
+      Outputs.push_back(getConstant(C1.udiv(C2), SVT));
+      break;
+    case ISD::UREM:
+      if (!C2.getBoolValue())
+        return SDValue();
+      Outputs.push_back(getConstant(C1.urem(C2), SVT));
+      break;
+    case ISD::SDIV:
+      if (!C2.getBoolValue())
+        return SDValue();
+      Outputs.push_back(getConstant(C1.sdiv(C2), SVT));
+      break;
+    case ISD::SREM:
+      if (!C2.getBoolValue())
+        return SDValue();
+      Outputs.push_back(getConstant(C1.srem(C2), SVT));
+      break;
+    case ISD::AND:
+      Outputs.push_back(getConstant(C1 & C2, SVT));
+      break;
+    case ISD::OR:
+      Outputs.push_back(getConstant(C1 | C2, SVT));
+      break;
+    case ISD::XOR:
+      Outputs.push_back(getConstant(C1 ^ C2, SVT));
+      break;
+    case ISD::SHL:
+      Outputs.push_back(getConstant(C1 << C2, SVT));
+      break;
+    case ISD::SRL:
+      Outputs.push_back(getConstant(C1.lshr(C2), SVT));
+      break;
+    case ISD::SRA:
+      Outputs.push_back(getConstant(C1.ashr(C2), SVT));
+      break;
+    case ISD::ROTL:
+      Outputs.push_back(getConstant(C1.rotl(C2), SVT));
+      break;
+    case ISD::ROTR:
+      Outputs.push_back(getConstant(C1.rotr(C2), SVT));
+      break;
+    default:
+      return SDValue();
+    }
   }
 
-  return SDValue();
+  // Handle the scalar case first.
+  if (Outputs.size() == 1)
+    return Outputs.back();
+
+  // Otherwise build a big vector out of the scalar elements we generated.
+  return getNode(ISD::BUILD_VECTOR, DebugLoc(), VT, Outputs.data(),
+                 Outputs.size());
 }
 
-SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, EVT VT,
-                              SDValue N1, SDValue N2) {
+SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, EVT VT, SDValue N1,
+                              SDValue N2) {
   ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.getNode());
   ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2.getNode());
   switch (Opcode) {
@@ -3013,16 +3086,14 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, EVT VT,
   }
   }
 
-  if (N1C) {
-    if (N2C) {
-      SDValue SV = FoldConstantArithmetic(Opcode, VT, N1C, N2C);
-      if (SV.getNode()) return SV;
-    } else {      // Cannonicalize constant to RHS if commutative
-      if (isCommutativeBinOp(Opcode)) {
-        std::swap(N1C, N2C);
-        std::swap(N1, N2);
-      }
-    }
+  // Perform trivial constant folding.
+  SDValue SV = FoldConstantArithmetic(Opcode, VT, N1.getNode(), N2.getNode());
+  if (SV.getNode()) return SV;
+
+  // Canonicalize constant to RHS if commutative.
+  if (N1C && !N2C && isCommutativeBinOp(Opcode)) {
+    std::swap(N1C, N2C);
+    std::swap(N1, N2);
   }
 
   // Constant fold FP operations.
@@ -3030,7 +3101,7 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, EVT VT,
   ConstantFPSDNode *N2CFP = dyn_cast<ConstantFPSDNode>(N2.getNode());
   if (N1CFP) {
     if (!N2CFP && isCommutativeBinOp(Opcode)) {
-      // Cannonicalize constant to RHS if commutative
+      // Canonicalize constant to RHS if commutative.
       std::swap(N1CFP, N2CFP);
       std::swap(N1, N2);
     } else if (N2CFP) {
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 9a68927103..4cd0fc484a 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -5032,9 +5032,14 @@ SDValue PPCTargetLowering::LowerBUILD_VECTOR(SDValue Op,
   // If this value is in the range [-32,30] and is even, use:
   //    tmp = VSPLTI[bhw], result = add tmp, tmp
   if (SextVal >= -32 && SextVal <= 30 && (SextVal & 1) == 0) {
+    // FIXME: This is currently disabled because the ADD will be folded back
+    // into an invalid BUILD_VECTOR immediately.
+    return SDValue();
+#if 0
     SDValue Res = BuildSplatI(SextVal >> 1, SplatSize, MVT::Other, DAG, dl);
     Res = DAG.getNode(ISD::ADD, dl, Res.getValueType(), Res, Res);
     return DAG.getNode(ISD::BITCAST, dl, Op.getValueType(), Res);
+#endif
   }
 
   // If this is 0x8000_0000 x 4, turn into vspltisw + vslw.  If it is
diff --git a/test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll b/test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll
index 8802b97d2a..00a402e0e4 100644
--- a/test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll
+++ b/test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll
@@ -1,5 +1,6 @@
 ; RUN: llc < %s -march=ppc32 -mcpu=g5 | grep vadduhm
 ; RUN: llc < %s -march=ppc32 -mcpu=g5 | grep vsubuhm
+; XFAIL: *
 
 define <4 x i32> @test() nounwind {
 	ret <4 x i32> < i32 4293066722, i32 4293066722, i32 4293066722, i32 4293066722>
diff --git a/test/CodeGen/X86/2011-11-30-or.ll b/test/CodeGen/X86/2011-11-30-or.ll
index f66248bc5a..8ac4632329 100644
--- a/test/CodeGen/X86/2011-11-30-or.ll
+++ b/test/CodeGen/X86/2011-11-30-or.ll
@@ -8,9 +8,9 @@ target triple = "x86_64-apple-macosx10.6.6"
 ; CHECK: pblendvb        %xmm1, %xmm2
 ; CHECK: ret
 
-define void @select_func() {
+define void @select_func(<8 x i16> %in) {
 entry:
-  %c.lobit.i.i.i = ashr <8 x i16> <i16 17, i16 5, i16 1, i16 15, i16 19, i16 15, i16 4, i16 1> , <i16 15, i16 15, i16 15, i16 15, i16 15, i16 15, i16 15, i16 15>
+  %c.lobit.i.i.i = ashr <8 x i16> %in, <i16 15, i16 15, i16 15, i16 15, i16 15, i16 15, i16 15, i16 15>
   %and.i56.i.i.i = and <8 x i16> %c.lobit.i.i.i, <i16 25, i16 8, i16 65, i16 25, i16 8, i16 95, i16 15, i16 45>
   %and.i5.i.i.i = bitcast <8 x i16> %and.i56.i.i.i to <2 x i64>
   %neg.i.i.i.i = xor <8 x i16> %c.lobit.i.i.i, <i16 -1, i16 -1, i16 -1, i16 -1, i16 -1, i16 -1, i16 -1, i16 -1>
diff --git a/test/CodeGen/X86/blend-msb.ll b/test/CodeGen/X86/blend-msb.ll
index 34445428ea..2b6b9ef8f3 100644
--- a/test/CodeGen/X86/blend-msb.ll
+++ b/test/CodeGen/X86/blend-msb.ll
@@ -5,7 +5,8 @@
 ; shifting the needed bit to the MSB, and not using shl+sra.
 
 ;CHECK: vsel_float
-;CHECK: pslld
+;CHECK: movl $-2147483648
+;CHECK-NEXT: movd
 ;CHECK-NEXT: blendvps
 ;CHECK: ret
 define <4 x float> @vsel_float(<4 x float> %v1, <4 x float> %v2) {
@@ -14,7 +15,8 @@ define <4 x float> @vsel_float(<4 x float> %v1, <4 x float> %v2) {
 }
 
 ;CHECK: vsel_4xi8
-;CHECK: pslld
+;CHECK: movl $-2147483648
+;CHECK-NEXT: movd
 ;CHECK-NEXT: blendvps
 ;CHECK: ret
 define <4 x i8> @vsel_4xi8(<4 x i8> %v1, <4 x i8> %v2) {
diff --git a/test/CodeGen/X86/vector-gep.ll b/test/CodeGen/X86/vector-gep.ll
index d08e2a0746..ec93ce0761 100644
--- a/test/CodeGen/X86/vector-gep.ll
+++ b/test/CodeGen/X86/vector-gep.ll
@@ -8,10 +8,8 @@ entry:
   %vecinit2.i = insertelement <4 x i32*> %vecinit.i, i32* %ptr, i32 1
   %vecinit4.i = insertelement <4 x i32*> %vecinit2.i, i32* %ptr, i32 2
   %vecinit6.i = insertelement <4 x i32*> %vecinit4.i, i32* %ptr, i32 3
-;CHECK: pslld $2
 ;CHECK: padd
   %A2 = getelementptr <4 x i32*> %vecinit6.i, <4 x i32> <i32 1, i32 2, i32 3, i32 4>
-;CHECK: pslld $2
 ;CHECK: padd
   %A3 = getelementptr <4 x i32*> %A2, <4 x i32> <i32 10, i32 14, i32 19, i32 233>
   ret <4 x i32*> %A3
@@ -21,7 +19,6 @@ entry:
 ;CHECK: AGEP1:
 define i32 @AGEP1(<4 x i32*> %param) nounwind {
 entry:
-;CHECK: pslld $2
 ;CHECK: padd
   %A2 = getelementptr <4 x i32*> %param, <4 x i32> <i32 1, i32 2, i32 3, i32 4>
   %k = extractelement <4 x i32*> %A2, i32 3