From 1a7eec68a9b38314f01a8cd795d3eec92d996136 Mon Sep 17 00:00:00 2001 From: Joerg Sonnenberger Date: Tue, 15 Nov 2016 12:39:46 +0000 Subject: [PATCH] Introduce TLI predicative for base-relative Jump Tables. For 64bit ABIs it is common practice to use relative Jump Tables with potentially different relocation bases. As the logic for the jump table itself doesn't depend on the relocation base, make it easier for targets to use the generic logic. Start by dropping the now redundant MIPS logic. Differential Revision: https://reviews.llvm.org/D26578 llvm-svn: 286951 --- llvm/include/llvm/Target/TargetLowering.h | 4 ++ llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp | 2 +- llvm/lib/Target/Mips/MipsISelLowering.cpp | 37 +------------------ llvm/lib/Target/Mips/MipsISelLowering.h | 5 ++- 4 files changed, 10 insertions(+), 38 deletions(-) diff --git a/llvm/include/llvm/Target/TargetLowering.h b/llvm/include/llvm/Target/TargetLowering.h index 826b4d5a1804..d880516e42fe 100644 --- a/llvm/include/llvm/Target/TargetLowering.h +++ b/llvm/include/llvm/Target/TargetLowering.h @@ -1057,6 +1057,10 @@ public: /// Zero if no limit. unsigned getMaximumJumpTableSize() const; + virtual bool isJumpTableRelative() const { + return TM.isPositionIndependent(); + } + /// If a physical register, this specifies the register that /// llvm.savestack/llvm.restorestack should save and restore. unsigned getStackPointerRegisterToSaveRestore() const { diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp index bce58d18b4ca..d98a81b2f23f 100644 --- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp @@ -3566,7 +3566,7 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) { ISD::SEXTLOAD, dl, PTy, Chain, Addr, MachinePointerInfo::getJumpTable(DAG.getMachineFunction()), MemVT); Addr = LD; - if (TM.isPositionIndependent()) { + if (TLI.isJumpTableRelative()) { // For PIC, the sequence is: // BRIND(load(Jumptable + index) + RelocBase) // RelocBase can be JumpTable, GOT or some sort of global base. diff --git a/llvm/lib/Target/Mips/MipsISelLowering.cpp b/llvm/lib/Target/Mips/MipsISelLowering.cpp index 3b831157c8dc..783714c40d39 100644 --- a/llvm/lib/Target/Mips/MipsISelLowering.cpp +++ b/llvm/lib/Target/Mips/MipsISelLowering.cpp @@ -268,7 +268,7 @@ MipsTargetLowering::MipsTargetLowering(const MipsTargetMachine &TM, AddPromotedToType(ISD::SETCC, MVT::i1, MVT::i32); // Mips Custom Operations - setOperationAction(ISD::BR_JT, MVT::Other, Custom); + setOperationAction(ISD::BR_JT, MVT::Other, Expand); setOperationAction(ISD::GlobalAddress, MVT::i32, Custom); setOperationAction(ISD::BlockAddress, MVT::i32, Custom); setOperationAction(ISD::GlobalTLSAddress, MVT::i32, Custom); @@ -910,7 +910,6 @@ LowerOperation(SDValue Op, SelectionDAG &DAG) const { switch (Op.getOpcode()) { - case ISD::BR_JT: return lowerBR_JT(Op, DAG); case ISD::BRCOND: return lowerBRCOND(Op, DAG); case ISD::ConstantPool: return lowerConstantPool(Op, DAG); case ISD::GlobalAddress: return lowerGlobalAddress(Op, DAG); @@ -1676,40 +1675,6 @@ MachineBasicBlock *MipsTargetLowering::emitSEL_D(MachineInstr &MI, return BB; } -//===----------------------------------------------------------------------===// -// Misc Lower Operation implementation -//===----------------------------------------------------------------------===// -SDValue MipsTargetLowering::lowerBR_JT(SDValue Op, SelectionDAG &DAG) const { - SDValue Chain = Op.getOperand(0); - SDValue Table = Op.getOperand(1); - SDValue Index = Op.getOperand(2); - SDLoc DL(Op); - auto &TD = DAG.getDataLayout(); - EVT PTy = getPointerTy(TD); - unsigned EntrySize = - DAG.getMachineFunction().getJumpTableInfo()->getEntrySize(TD); - - Index = DAG.getNode(ISD::MUL, DL, PTy, Index, - DAG.getConstant(EntrySize, DL, PTy)); - SDValue Addr = DAG.getNode(ISD::ADD, DL, PTy, Index, Table); - - EVT MemVT = EVT::getIntegerVT(*DAG.getContext(), EntrySize * 8); - Addr = DAG.getExtLoad( - ISD::SEXTLOAD, DL, PTy, Chain, Addr, - MachinePointerInfo::getJumpTable(DAG.getMachineFunction()), MemVT); - Chain = Addr.getValue(1); - - if (isPositionIndependent() || ABI.IsN64()) { - // For PIC, the sequence is: - // BRIND(load(Jumptable + index) + RelocBase) - // RelocBase can be JumpTable, GOT or some sort of global base. - Addr = DAG.getNode(ISD::ADD, DL, PTy, Addr, - getPICJumpTableRelocBase(Table, DAG)); - } - - return DAG.getNode(ISD::BRIND, DL, MVT::Other, Chain, Addr); -} - SDValue MipsTargetLowering::lowerBRCOND(SDValue Op, SelectionDAG &DAG) const { // The first operand is the chain, the second is the condition, the third is // the block to branch to if the condition is true. diff --git a/llvm/lib/Target/Mips/MipsISelLowering.h b/llvm/lib/Target/Mips/MipsISelLowering.h index 767eee7a995d..cddf0903ca6a 100644 --- a/llvm/lib/Target/Mips/MipsISelLowering.h +++ b/llvm/lib/Target/Mips/MipsISelLowering.h @@ -296,6 +296,10 @@ namespace llvm { return SrcAS < 256 && DestAS < 256; } + bool isJumpTableRelative() const override { + return getTargetMachine().isPositionIndependent() || ABI.IsN64(); + } + protected: SDValue getGlobalReg(SelectionDAG &DAG, EVT Ty) const; @@ -426,7 +430,6 @@ namespace llvm { TargetLowering::CallLoweringInfo &CLI) const; // Lower Operand specifics - SDValue lowerBR_JT(SDValue Op, SelectionDAG &DAG) const; SDValue lowerBRCOND(SDValue Op, SelectionDAG &DAG) const; SDValue lowerConstantPool(SDValue Op, SelectionDAG &DAG) const; SDValue lowerGlobalAddress(SDValue Op, SelectionDAG &DAG) const;