X86 vector element shift-by-immediate instructions take i8 immediates. Make

the instruction defenitions and ISEL reflect this.

Prior to this patch these instructions took an i32i8imm, and the high bits were
dropped during encoding. This led to incorrect behavior for shifts by
immediates higher than 255. This patch fixes that issue by detecting large
immediate shifts and returning constant zero (for logical shifts) or capping
the shift amount at an encodable value (for arithmetic shifts).

Fixes <rdar://problem/14968098>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193096 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 61 insertions, 48 deletions

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index dea4a46..e8918f4 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -10952,6 +10952,26 @@ static SDValue LowerVACOPY(SDValue Op, const X86Subtarget *Subtarget,
                        MachinePointerInfo(DstSV), MachinePointerInfo(SrcSV));
 }
 
+// getTargetVShiftByConstNode - Handle vector element shifts where the shift
+// amount is a constant. Takes immediate version of shift as input.
+static SDValue getTargetVShiftByConstNode(unsigned Opc, SDLoc dl, EVT VT,
+                                          SDValue SrcOp, uint64_t ShiftAmt,
+                                          SelectionDAG &DAG) {
+
+  // Check for ShiftAmt >= element width
+  if (ShiftAmt >= VT.getVectorElementType().getSizeInBits()) {
+    if (Opc == X86ISD::VSRAI)
+      ShiftAmt = VT.getVectorElementType().getSizeInBits() - 1;
+    else
+      return DAG.getConstant(0, VT);
+  }
+
+  assert((Opc == X86ISD::VSHLI || Opc == X86ISD::VSRLI || Opc == X86ISD::VSRAI)
+         && "Unknown target vector shift-by-constant node");
+
+  return DAG.getNode(Opc, dl, VT, SrcOp, DAG.getConstant(ShiftAmt, MVT::i8));
+}
+
 // getTargetVShiftNode - Handle vector element shifts where the shift amount
 // may or may not be a constant. Takes immediate version of shift as input.
 static SDValue getTargetVShiftNode(unsigned Opc, SDLoc dl, EVT VT,
@@ -10959,18 +10979,10 @@ static SDValue getTargetVShiftNode(unsigned Opc, SDLoc dl, EVT VT,
                                    SelectionDAG &DAG) {
   assert(ShAmt.getValueType() == MVT::i32 && "ShAmt is not i32");
 
-  if (isa<ConstantSDNode>(ShAmt)) {
-    // Constant may be a TargetConstant. Use a regular constant.
-    uint32_t ShiftAmt = cast<ConstantSDNode>(ShAmt)->getZExtValue();
-    switch (Opc) {
-      default: llvm_unreachable("Unknown target vector shift node");
-      case X86ISD::VSHLI:
-      case X86ISD::VSRLI:
-      case X86ISD::VSRAI:
-        return DAG.getNode(Opc, dl, VT, SrcOp,
-                           DAG.getConstant(ShiftAmt, MVT::i32));
-    }
-  }
+  // Catch shift-by-constant.
+  if (ConstantSDNode *CShAmt = dyn_cast<ConstantSDNode>(ShAmt))
+    return getTargetVShiftByConstNode(Opc, dl, VT, SrcOp,
+                                      CShAmt->getZExtValue(), DAG);
 
   // Change opcode to non-immediate version
   switch (Opc) {
@@ -12416,10 +12428,8 @@ static SDValue LowerMUL(SDValue Op, const X86Subtarget *Subtarget,
   //  AhiBlo = psllqi(AhiBlo, 32);
   //  return AloBlo + AloBhi + AhiBlo;
 
-  SDValue ShAmt = DAG.getConstant(32, MVT::i32);
-
-  SDValue Ahi = DAG.getNode(X86ISD::VSRLI, dl, VT, A, ShAmt);
-  SDValue Bhi = DAG.getNode(X86ISD::VSRLI, dl, VT, B, ShAmt);
+  SDValue Ahi = getTargetVShiftByConstNode(X86ISD::VSRLI, dl, VT, A, 32, DAG);
+  SDValue Bhi = getTargetVShiftByConstNode(X86ISD::VSRLI, dl, VT, B, 32, DAG);
 
   // Bit cast to 32-bit vectors for MULUDQ
   EVT MulVT = (VT == MVT::v2i64) ? MVT::v4i32 :
@@ -12433,8 +12443,8 @@ static SDValue LowerMUL(SDValue Op, const X86Subtarget *Subtarget,
   SDValue AloBhi = DAG.getNode(X86ISD::PMULUDQ, dl, VT, A, Bhi);
   SDValue AhiBlo = DAG.getNode(X86ISD::PMULUDQ, dl, VT, Ahi, B);
 
-  AloBhi = DAG.getNode(X86ISD::VSHLI, dl, VT, AloBhi, ShAmt);
-  AhiBlo = DAG.getNode(X86ISD::VSHLI, dl, VT, AhiBlo, ShAmt);
+  AloBhi = getTargetVShiftByConstNode(X86ISD::VSHLI, dl, VT, AloBhi, 32, DAG);
+  AhiBlo = getTargetVShiftByConstNode(X86ISD::VSHLI, dl, VT, AhiBlo, 32, DAG);
 
   SDValue Res = DAG.getNode(ISD::ADD, dl, VT, AloBlo, AloBhi);
   return DAG.getNode(ISD::ADD, dl, VT, Res, AhiBlo);
@@ -12462,7 +12472,7 @@ static SDValue LowerSDIV(SDValue Op, SelectionDAG &DAG) {
 
   if ((SplatValue != 0) &&
       (SplatValue.isPowerOf2() || (-SplatValue).isPowerOf2())) {
-    unsigned lg2 = SplatValue.countTrailingZeros();
+    unsigned Lg2 = SplatValue.countTrailingZeros();
     // Splat the sign bit.
     SmallVector<SDValue, 16> Sz(NumElts,
                                 DAG.getConstant(EltTy.getSizeInBits() - 1,
@@ -12472,13 +12482,13 @@ static SDValue LowerSDIV(SDValue Op, SelectionDAG &DAG) {
                                           NumElts));
     // Add (N0 < 0) ? abs2 - 1 : 0;
     SmallVector<SDValue, 16> Amt(NumElts,
-                                 DAG.getConstant(EltTy.getSizeInBits() - lg2,
+                                 DAG.getConstant(EltTy.getSizeInBits() - Lg2,
                                                  EltTy));
     SDValue SRL = DAG.getNode(ISD::SRL, dl, VT, SGN,
                               DAG.getNode(ISD::BUILD_VECTOR, dl, VT, &Amt[0],
                                           NumElts));
     SDValue ADD = DAG.getNode(ISD::ADD, dl, VT, N0, SRL);
-    SmallVector<SDValue, 16> Lg2Amt(NumElts, DAG.getConstant(lg2, EltTy));
+    SmallVector<SDValue, 16> Lg2Amt(NumElts, DAG.getConstant(Lg2, EltTy));
     SDValue SRA = DAG.getNode(ISD::SRA, dl, VT, ADD,
                               DAG.getNode(ISD::BUILD_VECTOR, dl, VT, &Lg2Amt[0],
                                           NumElts));
@@ -12514,21 +12524,22 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG,
           (Subtarget->hasAVX512() &&
            (VT == MVT::v8i64 || VT == MVT::v16i32))) {
         if (Op.getOpcode() == ISD::SHL)
-          return DAG.getNode(X86ISD::VSHLI, dl, VT, R,
-                             DAG.getConstant(ShiftAmt, MVT::i32));
+          return getTargetVShiftByConstNode(X86ISD::VSHLI, dl, VT, R, ShiftAmt,
+                                            DAG);
         if (Op.getOpcode() == ISD::SRL)
-          return DAG.getNode(X86ISD::VSRLI, dl, VT, R,
-                             DAG.getConstant(ShiftAmt, MVT::i32));
+          return getTargetVShiftByConstNode(X86ISD::VSRLI, dl, VT, R, ShiftAmt,
+                                            DAG);
         if (Op.getOpcode() == ISD::SRA && VT != MVT::v2i64 && VT != MVT::v4i64)
-          return DAG.getNode(X86ISD::VSRAI, dl, VT, R,
-                             DAG.getConstant(ShiftAmt, MVT::i32));
+          return getTargetVShiftByConstNode(X86ISD::VSRAI, dl, VT, R, ShiftAmt,
+                                            DAG);
       }
 
       if (VT == MVT::v16i8) {
         if (Op.getOpcode() == ISD::SHL) {
           // Make a large shift.
-          SDValue SHL = DAG.getNode(X86ISD::VSHLI, dl, MVT::v8i16, R,
-                                    DAG.getConstant(ShiftAmt, MVT::i32));
+          SDValue SHL = getTargetVShiftByConstNode(X86ISD::VSHLI, dl,
+                                                   MVT::v8i16, R, ShiftAmt,
+                                                   DAG); 
           SHL = DAG.getNode(ISD::BITCAST, dl, VT, SHL);
           // Zero out the rightmost bits.
           SmallVector<SDValue, 16> V(16,
@@ -12539,8 +12550,9 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG,
         }
         if (Op.getOpcode() == ISD::SRL) {
           // Make a large shift.
-          SDValue SRL = DAG.getNode(X86ISD::VSRLI, dl, MVT::v8i16, R,
-                                    DAG.getConstant(ShiftAmt, MVT::i32));
+          SDValue SRL = getTargetVShiftByConstNode(X86ISD::VSRLI, dl,
+                                                   MVT::v8i16, R, ShiftAmt,
+                                                   DAG);
           SRL = DAG.getNode(ISD::BITCAST, dl, VT, SRL);
           // Zero out the leftmost bits.
           SmallVector<SDValue, 16> V(16,
@@ -12571,8 +12583,9 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG,
       if (Subtarget->hasInt256() && VT == MVT::v32i8) {
         if (Op.getOpcode() == ISD::SHL) {
           // Make a large shift.
-          SDValue SHL = DAG.getNode(X86ISD::VSHLI, dl, MVT::v16i16, R,
-                                    DAG.getConstant(ShiftAmt, MVT::i32));
+          SDValue SHL = getTargetVShiftByConstNode(X86ISD::VSHLI, dl,
+                                                   MVT::v16i16, R, ShiftAmt,
+                                                   DAG);
           SHL = DAG.getNode(ISD::BITCAST, dl, VT, SHL);
           // Zero out the rightmost bits.
           SmallVector<SDValue, 32> V(32,
@@ -12583,8 +12596,9 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG,
         }
         if (Op.getOpcode() == ISD::SRL) {
           // Make a large shift.
-          SDValue SRL = DAG.getNode(X86ISD::VSRLI, dl, MVT::v16i16, R,
-                                    DAG.getConstant(ShiftAmt, MVT::i32));
+          SDValue SRL = getTargetVShiftByConstNode(X86ISD::VSRLI, dl,
+                                                   MVT::v16i16, R, ShiftAmt,
+                                                   DAG);
           SRL = DAG.getNode(ISD::BITCAST, dl, VT, SRL);
           // Zero out the leftmost bits.
           SmallVector<SDValue, 32> V(32,
@@ -12649,14 +12663,14 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG,
     default:
       llvm_unreachable("Unknown shift opcode!");
     case ISD::SHL:
-      return DAG.getNode(X86ISD::VSHLI, dl, VT, R,
-                         DAG.getConstant(ShiftAmt, MVT::i32));
+      return getTargetVShiftByConstNode(X86ISD::VSHLI, dl, VT, R, ShiftAmt,
+                                        DAG);
     case ISD::SRL:
-      return DAG.getNode(X86ISD::VSRLI, dl, VT, R,
-                         DAG.getConstant(ShiftAmt, MVT::i32));
+      return getTargetVShiftByConstNode(X86ISD::VSRLI, dl, VT, R, ShiftAmt,
+                                        DAG);
     case ISD::SRA:
-      return DAG.getNode(X86ISD::VSRAI, dl, VT, R,
-                         DAG.getConstant(ShiftAmt, MVT::i32));
+      return getTargetVShiftByConstNode(X86ISD::VSRAI, dl, VT, R, ShiftAmt,
+                                        DAG);
     }
   }
 
@@ -12869,8 +12883,7 @@ static SDValue LowerShift(SDValue Op, const X86Subtarget* Subtarget,
 
     // r = VSELECT(r, psllw(r & (char16)15, 4), a);
     SDValue M = DAG.getNode(ISD::AND, dl, VT, R, CM1);
-    M = getTargetVShiftNode(X86ISD::VSHLI, dl, MVT::v8i16, M,
-                            DAG.getConstant(4, MVT::i32), DAG);
+    M = getTargetVShiftByConstNode(X86ISD::VSHLI, dl, MVT::v8i16, M, 4, DAG);
     M = DAG.getNode(ISD::BITCAST, dl, VT, M);
     R = DAG.getNode(ISD::VSELECT, dl, VT, OpVSel, M, R);
 
@@ -12881,8 +12894,7 @@ static SDValue LowerShift(SDValue Op, const X86Subtarget* Subtarget,
 
     // r = VSELECT(r, psllw(r & (char16)63, 2), a);
     M = DAG.getNode(ISD::AND, dl, VT, R, CM2);
-    M = getTargetVShiftNode(X86ISD::VSHLI, dl, MVT::v8i16, M,
-                            DAG.getConstant(2, MVT::i32), DAG);
+    M = getTargetVShiftByConstNode(X86ISD::VSHLI, dl, MVT::v8i16, M, 2, DAG);
     M = DAG.getNode(ISD::BITCAST, dl, VT, M);
     R = DAG.getNode(ISD::VSELECT, dl, VT, OpVSel, M, R);
 
@@ -13025,7 +13037,6 @@ SDValue X86TargetLowering::LowerSIGN_EXTEND_INREG(SDValue Op,
 
   unsigned BitsDiff = VT.getScalarType().getSizeInBits() -
                       ExtraVT.getScalarType().getSizeInBits();
-  SDValue ShAmt = DAG.getConstant(BitsDiff, MVT::i32);
 
   switch (VT.getSimpleVT().SimpleTy) {
     default: return SDValue();
@@ -13075,8 +13086,10 @@ SDValue X86TargetLowering::LowerSIGN_EXTEND_INREG(SDValue Op,
       }
 
       // If the above didn't work, then just use Shift-Left + Shift-Right.
-      Tmp1 = getTargetVShiftNode(X86ISD::VSHLI, dl, VT, Op0, ShAmt, DAG);
-      return getTargetVShiftNode(X86ISD::VSRAI, dl, VT, Tmp1, ShAmt, DAG);
+      Tmp1 = getTargetVShiftByConstNode(X86ISD::VSHLI, dl, VT, Op0, BitsDiff,
+                                        DAG);
+      return getTargetVShiftByConstNode(X86ISD::VSRAI, dl, VT, Tmp1, BitsDiff,
+                                        DAG);
     }
   }
 }