Add shifts and reg-imm address matching
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75927 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
index a318536..f0da426 100644
--- a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
+++ b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
@@ -67,6 +67,8 @@
private:
SDNode *Select(SDValue Op);
+ bool SelectAddrRI(const SDValue& Op, SDValue& Addr,
+ SDValue &Base, SDValue &Disp);
#ifndef NDEBUG
unsigned Indent;
@@ -82,6 +84,91 @@
return new SystemZDAGToDAGISel(TM, OptLevel);
}
+/// isImmSExt20 - This method tests to see if the node is either a 32-bit
+/// or 64-bit immediate, and if the value can be accurately represented as a
+/// sign extension from a 20-bit value. If so, this returns true and the
+/// immediate.
+static bool isImmSExt20(SDNode *N, int32_t &Imm) {
+ if (N->getOpcode() != ISD::Constant)
+ return false;
+
+ Imm = (int32_t)cast<ConstantSDNode>(N)->getZExtValue();
+
+ if (Imm >= -524288 && Imm <= 524287) {
+ if (N->getValueType(0) == MVT::i32)
+ return Imm == (int32_t)cast<ConstantSDNode>(N)->getZExtValue();
+ else
+ return Imm == (int64_t)cast<ConstantSDNode>(N)->getZExtValue();
+ }
+
+ return false;
+}
+
+static bool isImmSExt20(SDValue Op, int32_t &Imm) {
+ return isImmSExt20(Op.getNode(), Imm);
+}
+
+/// Returns true if the address can be represented by a base register plus
+/// a signed 20-bit displacement [r+imm].
+bool SystemZDAGToDAGISel::SelectAddrRI(const SDValue& Op, SDValue& Addr,
+ SDValue &Base, SDValue &Disp) {
+ // FIXME dl should come from parent load or store, not from address
+ DebugLoc dl = Addr.getDebugLoc();
+ MVT VT = Addr.getValueType();
+
+ if (Addr.getOpcode() == ISD::ADD) {
+ int32_t Imm = 0;
+ if (isImmSExt20(Addr.getOperand(1), Imm)) {
+ Disp = CurDAG->getTargetConstant(Imm, MVT::i32);
+ if (FrameIndexSDNode *FI =
+ dyn_cast<FrameIndexSDNode>(Addr.getOperand(0))) {
+ Base = CurDAG->getTargetFrameIndex(FI->getIndex(), VT);
+ } else {
+ Base = Addr.getOperand(0);
+ }
+ return true; // [r+i]
+ }
+ } else if (Addr.getOpcode() == ISD::OR) {
+ int32_t Imm = 0;
+ if (isImmSExt20(Addr.getOperand(1), Imm)) {
+ // If this is an or of disjoint bitfields, we can codegen this as an add
+ // (for better address arithmetic) if the LHS and RHS of the OR are
+ // provably disjoint.
+ APInt LHSKnownZero, LHSKnownOne;
+ CurDAG->ComputeMaskedBits(Addr.getOperand(0),
+ APInt::getAllOnesValue(Addr.getOperand(0)
+ .getValueSizeInBits()),
+ 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.
+ Base = Addr.getOperand(0);
+ Disp = CurDAG->getTargetConstant(Imm, MVT::i32);
+ return true;
+ }
+ }
+ } else if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr)) {
+ // Loading from a constant address.
+
+ // If this address fits entirely in a 20-bit sext immediate field, codegen
+ // this as "d(r0)"
+ int32_t Imm;
+ if (isImmSExt20(CN, Imm)) {
+ Disp = CurDAG->getTargetConstant(Imm, MVT::i32);
+ Base = CurDAG->getRegister(SystemZ::R0D, MVT::i64);
+ return true;
+ }
+ }
+
+ Disp = CurDAG->getTargetConstant(0, MVT::i32);
+ if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Addr))
+ Base = CurDAG->getTargetFrameIndex(FI->getIndex(), VT);
+ else
+ Base = Addr;
+ return true; // [r+0]
+}
+
/// InstructionSelect - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.