Always compute all the bits in ComputeMaskedBits.

This allows us to keep passing reduced masks to SimplifyDemandedBits, but
know about all the bits if SimplifyDemandedBits fails. This allows instcombine
to simplify cases like the one in the included testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154011 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 5 insertions, 17 deletions

diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 6651d141fb..5a04888dd4 100644
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -377,8 +377,8 @@ SDNode *PPCDAGToDAGISel::SelectBitfieldInsert(SDNode *N) {
   DebugLoc dl = N->getDebugLoc();
 
   APInt LKZ, LKO, RKZ, RKO;
-  CurDAG->ComputeMaskedBits(Op0, APInt::getAllOnesValue(32), LKZ, LKO);
-  CurDAG->ComputeMaskedBits(Op1, APInt::getAllOnesValue(32), RKZ, RKO);
+  CurDAG->ComputeMaskedBits(Op0, LKZ, LKO);
+  CurDAG->ComputeMaskedBits(Op1, RKZ, RKO);
 
   unsigned TargetMask = LKZ.getZExtValue();
   unsigned InsertMask = RKZ.getZExtValue();
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 746fc23c21..3b24951d1d 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -860,14 +860,10 @@ bool PPCTargetLowering::SelectAddressRegReg(SDValue N, SDValue &Base,
     APInt LHSKnownZero, LHSKnownOne;
     APInt RHSKnownZero, RHSKnownOne;
     DAG.ComputeMaskedBits(N.getOperand(0),
-                          APInt::getAllOnesValue(N.getOperand(0)
-                            .getValueSizeInBits()),
                           LHSKnownZero, LHSKnownOne);
 
     if (LHSKnownZero.getBoolValue()) {
       DAG.ComputeMaskedBits(N.getOperand(1),
-                            APInt::getAllOnesValue(N.getOperand(1)
-                              .getValueSizeInBits()),
                             RHSKnownZero, RHSKnownOne);
       // If all of the bits are known zero on the LHS or RHS, the add won't
       // carry.
@@ -922,10 +918,7 @@ bool PPCTargetLowering::SelectAddressRegImm(SDValue N, SDValue &Disp,
       // (for better address arithmetic) if the LHS and RHS of the OR are
       // provably disjoint.
       APInt LHSKnownZero, LHSKnownOne;
-      DAG.ComputeMaskedBits(N.getOperand(0),
-                            APInt::getAllOnesValue(N.getOperand(0)
-                                                   .getValueSizeInBits()),
-                            LHSKnownZero, LHSKnownOne);
+      DAG.ComputeMaskedBits(N.getOperand(0), LHSKnownZero, LHSKnownOne);
 
       if ((LHSKnownZero.getZExtValue()|~(uint64_t)imm) == ~0ULL) {
         // If all of the bits are known zero on the LHS or RHS, the add won't
@@ -1038,10 +1031,7 @@ bool PPCTargetLowering::SelectAddressRegImmShift(SDValue N, SDValue &Disp,
       // (for better address arithmetic) if the LHS and RHS of the OR are
       // provably disjoint.
       APInt LHSKnownZero, LHSKnownOne;
-      DAG.ComputeMaskedBits(N.getOperand(0),
-                            APInt::getAllOnesValue(N.getOperand(0)
-                                                   .getValueSizeInBits()),
-                            LHSKnownZero, LHSKnownOne);
+      DAG.ComputeMaskedBits(N.getOperand(0), LHSKnownZero, LHSKnownOne);
       if ((LHSKnownZero.getZExtValue()|~(uint64_t)imm) == ~0ULL) {
         // If all of the bits are known zero on the LHS or RHS, the add won't
         // carry.
@@ -5517,12 +5507,11 @@ SDValue PPCTargetLowering::PerformDAGCombine(SDNode *N,
 //===----------------------------------------------------------------------===//
 
 void PPCTargetLowering::computeMaskedBitsForTargetNode(const SDValue Op,
-                                                       const APInt &Mask,
                                                        APInt &KnownZero,
                                                        APInt &KnownOne,
                                                        const SelectionDAG &DAG,
                                                        unsigned Depth) const {
-  KnownZero = KnownOne = APInt(Mask.getBitWidth(), 0);
+  KnownZero = KnownOne = APInt(KnownZero.getBitWidth(), 0);
   switch (Op.getOpcode()) {
   default: break;
   case PPCISD::LBRX: {
diff --git a/lib/Target/PowerPC/PPCISelLowering.h b/lib/Target/PowerPC/PPCISelLowering.h
index 6a00989611..18eb072003 100644
--- a/lib/Target/PowerPC/PPCISelLowering.h
+++ b/lib/Target/PowerPC/PPCISelLowering.h
@@ -296,7 +296,6 @@ namespace llvm {
     virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
 
     virtual void computeMaskedBitsForTargetNode(const SDValue Op,
-                                                const APInt &Mask,
                                                 APInt &KnownZero,
                                                 APInt &KnownOne,
                                                 const SelectionDAG &DAG,