[RISCV] Codegen support for memory operations on global addresses

Differential Revision: https://reviews.llvm.org/D39103

llvm-svn: 317688

llvm/lib/Target/RISCV/RISCV.h

@@ -15,15 +15,21 @@
 #ifndef LLVM_LIB_TARGET_RISCV_RISCV_H
 #define LLVM_LIB_TARGET_RISCV_RISCV_H
 
-#include "MCTargetDesc/RISCVMCTargetDesc.h"
-#include "llvm/Target/TargetMachine.h"
+#include "MCTargetDesc/RISCVBaseInfo.h"
 
 namespace llvm {
 class RISCVTargetMachine;
+class AsmPrinter;
+class FunctionPass;
 class MCInst;
+class MCOperand;
 class MachineInstr;
+class MachineOperand;
 
-void LowerRISCVMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI);
+void LowerRISCVMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
+                                    const AsmPrinter &AP);
+bool LowerRISCVMachineOperandToMCOperand(const MachineOperand &MO,
+                                         MCOperand &MCOp, const AsmPrinter &AP);
 
 FunctionPass *createRISCVISelDag(RISCVTargetMachine &TM);
 }

llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp

@@ -43,6 +43,11 @@ public:
 
   bool emitPseudoExpansionLowering(MCStreamer &OutStreamer,
                                    const MachineInstr *MI);
+
+  // Wrapper needed for tblgenned pseudo lowering.
+  bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp) const {
+    return LowerRISCVMachineOperandToMCOperand(MO, MCOp, *this);
+  }
 };
 }
 
@@ -56,7 +61,7 @@ void RISCVAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     return;
 
   MCInst TmpInst;
-  LowerRISCVMachineInstrToMCInst(MI, TmpInst);
+  LowerRISCVMachineInstrToMCInst(MI, TmpInst, *this);
   EmitToStreamer(*OutStreamer, TmpInst);
 }
 

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -53,6 +53,7 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
     setLoadExtAction(N, XLenVT, MVT::i1, Promote);
 
   // TODO: add all necessary setOperationAction calls.
+  setOperationAction(ISD::GlobalAddress, XLenVT, Custom);
 
   setBooleanContents(ZeroOrOneBooleanContent);
 
@@ -66,6 +67,30 @@ SDValue RISCVTargetLowering::LowerOperation(SDValue Op,
   switch (Op.getOpcode()) {
   default:
     report_fatal_error("unimplemented operand");
+  case ISD::GlobalAddress:
+    return lowerGlobalAddress(Op, DAG);
+  }
+}
+
+SDValue RISCVTargetLowering::lowerGlobalAddress(SDValue Op,
+                                                SelectionDAG &DAG) const {
+  SDLoc DL(Op);
+  EVT Ty = Op.getValueType();
+  GlobalAddressSDNode *N = cast<GlobalAddressSDNode>(Op);
+  const GlobalValue *GV = N->getGlobal();
+  int64_t Offset = N->getOffset();
+
+  if (!isPositionIndependent() && !Subtarget.is64Bit()) {
+    SDValue GAHi =
+        DAG.getTargetGlobalAddress(GV, DL, Ty, Offset, RISCVII::MO_HI);
+    SDValue GALo =
+        DAG.getTargetGlobalAddress(GV, DL, Ty, Offset, RISCVII::MO_LO);
+    SDValue MNHi = SDValue(DAG.getMachineNode(RISCV::LUI, DL, Ty, GAHi), 0);
+    SDValue MNLo =
+        SDValue(DAG.getMachineNode(RISCV::ADDI, DL, Ty, MNHi, GALo), 0);
+    return MNLo;
+  } else {
+    report_fatal_error("Unable to lowerGlobalAddress");
   }
 }
 

llvm/lib/Target/RISCV/RISCVISelLowering.h

@@ -56,6 +56,7 @@ private:
                                          Type *Ty) const override {
     return true;
   }
+  SDValue lowerGlobalAddress(SDValue Op, SelectionDAG &DAG) const;
 };
 }
 

llvm/lib/Target/RISCV/RISCVMCInstLower.cpp

@@ -13,6 +13,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "RISCV.h"
+#include "MCTargetDesc/RISCVMCExpr.h"
+#include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/MC/MCAsmInfo.h"
@@ -24,27 +26,65 @@
 
 using namespace llvm;
 
-void llvm::LowerRISCVMachineInstrToMCInst(const MachineInstr *MI,
-                                          MCInst &OutMI) {
+static MCOperand lowerSymbolOperand(const MachineOperand &MO, MCSymbol *Sym,
+                                    const AsmPrinter &AP) {
+  MCContext &Ctx = AP.OutContext;
+  RISCVMCExpr::VariantKind Kind;
+
+  switch (MO.getTargetFlags()) {
+  default:
+    llvm_unreachable("Unknown target flag on GV operand");
+  case RISCVII::MO_None:
+    Kind = RISCVMCExpr::VK_RISCV_None;
+    break;
+  case RISCVII::MO_LO:
+    Kind = RISCVMCExpr::VK_RISCV_LO;
+    break;
+  case RISCVII::MO_HI:
+    Kind = RISCVMCExpr::VK_RISCV_HI;
+    break;
+  }
+
+  const MCExpr *ME =
+      MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None, Ctx);
+
+  if (!MO.isJTI() && MO.getOffset())
+    ME = MCBinaryExpr::createAdd(
+        ME, MCConstantExpr::create(MO.getOffset(), Ctx), Ctx);
+
+  ME = RISCVMCExpr::create(ME, Kind, Ctx);
+  return MCOperand::createExpr(ME);
+}
+
+bool llvm::LowerRISCVMachineOperandToMCOperand(const MachineOperand &MO,
+                                               MCOperand &MCOp,
+                                               const AsmPrinter &AP) {
+  switch (MO.getType()) {
+  default:
+    report_fatal_error("LowerRISCVMachineInstrToMCInst: unknown operand type");
+  case MachineOperand::MO_Register:
+    // Ignore all implicit register operands.
+    if (MO.isImplicit())
+      return false;
+    MCOp = MCOperand::createReg(MO.getReg());
+    break;
+  case MachineOperand::MO_Immediate:
+    MCOp = MCOperand::createImm(MO.getImm());
+    break;
+  case MachineOperand::MO_GlobalAddress:
+    MCOp = lowerSymbolOperand(MO, AP.getSymbol(MO.getGlobal()), AP);
+    break;
+  }
+  return true;
+}
+
+void llvm::LowerRISCVMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
+                                          const AsmPrinter &AP) {
   OutMI.setOpcode(MI->getOpcode());
 
   for (const MachineOperand &MO : MI->operands()) {
     MCOperand MCOp;
-    switch (MO.getType()) {
-    default:
-      report_fatal_error(
-          "LowerRISCVMachineInstrToMCInst: unknown operand type");
-    case MachineOperand::MO_Register:
-      // Ignore all implicit register operands.
-      if (MO.isImplicit())
-        continue;
-      MCOp = MCOperand::createReg(MO.getReg());
-      break;
-    case MachineOperand::MO_Immediate:
-      MCOp = MCOperand::createImm(MO.getImm());
-      break;
-    }
-
-    OutMI.addOperand(MCOp);
+    if (LowerRISCVMachineOperandToMCOperand(MO, MCOp, AP))
+      OutMI.addOperand(MCOp);
   }
 }

llvm/test/CodeGen/RISCV/mem.ll

@@ -159,6 +159,31 @@ define i16 @load_sext_zext_anyext_i1_i16(i1 *%a) nounwind {
   ret i16 %7
 }
 
+; Check load and store to a global
+@G = global i32 0
+
+define i32 @lw_sw_global(i32 %a) nounwind {
+; TODO: the addi should be folded in to the lw/sw operations
+; RV32I-LABEL: lw_sw_global:
+; RV32I:       # BB#0:
+; RV32I-NEXT:    lui a1, %hi(G)
+; RV32I-NEXT:    addi a2, a1, %lo(G)
+; RV32I-NEXT:    lw a1, 0(a2)
+; RV32I-NEXT:    sw a0, 0(a2)
+; RV32I-NEXT:    lui a2, %hi(G+36)
+; RV32I-NEXT:    addi a2, a2, %lo(G+36)
+; RV32I-NEXT:    lw a3, 0(a2)
+; RV32I-NEXT:    sw a0, 0(a2)
+; RV32I-NEXT:    addi a0, a1, 0
+; RV32I-NEXT:    jalr zero, ra, 0
+  %1 = load volatile i32, i32* @G
+  store i32 %a, i32* @G
+  %2 = getelementptr i32, i32* @G, i32 9
+  %3 = load volatile i32, i32* %2
+  store i32 %a, i32* %2
+  ret i32 %1
+}
+
 ; Ensure that 1 is added to the high 20 bits if bit 11 of the low part is 1
 define i32 @lw_sw_constant(i32 %a) nounwind {
 ; TODO: the addi should be folded in to the lw/sw

llvm/test/CodeGen/RISCV/wide-mem.ll

@@ -14,3 +14,21 @@ define i64 @load_i64(i64 *%a) nounwind {
   %1 = load i64, i64* %a
   ret i64 %1
 }
+
+@val64 = local_unnamed_addr global i64 2863311530, align 8
+
+; TODO: codegen on this should be improved. It shouldn't be necessary to
+; generate two addi
+define i64 @load_i64_global() nounwind {
+; RV32I-LABEL: load_i64_global:
+; RV32I:       # BB#0:
+; RV32I-NEXT:    lui a0, %hi(val64)
+; RV32I-NEXT:    addi a0, a0, %lo(val64)
+; RV32I-NEXT:    lw a0, 0(a0)
+; RV32I-NEXT:    lui a1, %hi(val64+4)
+; RV32I-NEXT:    addi a1, a1, %lo(val64+4)
+; RV32I-NEXT:    lw a1, 0(a1)
+; RV32I-NEXT:    jalr zero, ra, 0
+  %1 = load i64, i64* @val64
+  ret i64 %1
+}