[Xtensa] Implement asm representation of the Constant Pool.

[andreisfr]

Minor code formatting

[arsenm]

Tests?

llvm/lib/Target/Xtensa/XtensaAsmPrinter.cpp

106

use a raw_string_ostream with a SmallString?

197–198

Don't need string copy?

llvm/lib/Target/Xtensa/XtensaAsmPrinter.h

 public:
   explicit XtensaAsmPrinter(TargetMachine &TM,
                             std::unique_ptr<MCStreamer> Streamer)
       : AsmPrinter(TM, std::move(Streamer)), STI(TM.getMCSubtargetInfo()) {}
 
   // Override AsmPrinter.
   StringRef getPassName() const override { return "Xtensa Assembly Printer"; }
   void emitInstruction(const MachineInstr *MI) override;
+  void emitConstantPool() override;
+  void emitMachineConstantPoolValue(MachineConstantPoolValue *MCPV) override;
 };
 } // end namespace llvm
 
 #endif /* LLVM_LIB_TARGET_XTENSA_XTENSAASMPRINTER_H */

llvm/lib/Target/Xtensa/XtensaAsmPrinter.cpp

 //
 // This file contains a printer that converts from our internal representation
 // of machine-dependent LLVM code to GAS-format Xtensa assembly language.
 //
 //===----------------------------------------------------------------------===//
 
 #include "XtensaAsmPrinter.h"
 #include "TargetInfo/XtensaTargetInfo.h"
+#include "XtensaConstantPoolValue.h"
 #include "XtensaMCInstLower.h"
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCSymbolELF.h"
 #include "llvm/MC/TargetRegistry.h"
 
 using namespace llvm;
 
+static MCSymbolRefExpr::VariantKind
+getModifierVariantKind(XtensaCP::XtensaCPModifier Modifier) {
+  switch (Modifier) {
+  case XtensaCP::no_modifier:
+    return MCSymbolRefExpr::VK_None;
+  case XtensaCP::TPOFF:
+    return MCSymbolRefExpr::VK_TPOFF;
+  }
+  llvm_unreachable("Invalid XtensaCPModifier!");
+}
+
 void XtensaAsmPrinter::emitInstruction(const MachineInstr *MI) {
   XtensaMCInstLower Lower(MF->getContext(), *this);
   MCInst LoweredMI;
   Lower.lower(MI, LoweredMI);
   EmitToStreamer(*OutStreamer, LoweredMI);
 }
 
+/// EmitConstantPool - Print to the current output stream assembly
+/// representations of the constants in the constant pool MCP. This is
+/// used to print out constants which have been "spilled to memory" by
+/// the code generator.
+void XtensaAsmPrinter::emitConstantPool() {
+  const Function &F = MF->getFunction();
+  const MachineConstantPool *MCP = MF->getConstantPool();
+  const std::vector<MachineConstantPoolEntry> &CP = MCP->getConstants();
+  if (CP.empty())
+    return;
+
+  for (unsigned i = 0, e = CP.size(); i != e; ++i) {
+    const MachineConstantPoolEntry &CPE = CP[i];
+
+    if (i == 0) {
+      if (OutStreamer->hasRawTextSupport()) {
+        OutStreamer->switchSection(
+            getObjFileLowering().SectionForGlobal(&F, TM));
+        OutStreamer->emitRawText(StringRef("\t.literal_position\n"));
+      } else {
+        MCSectionELF *CS =
+            (MCSectionELF *)getObjFileLowering().SectionForGlobal(&F, TM);
+        std::string CSectionName = CS->getName().str();
+        std::size_t Pos = CSectionName.find(".text");
+        std::string SectionName;
+        if (Pos != std::string::npos) {
+          if (Pos > 0)
+            SectionName = CSectionName.substr(0, Pos + 5);
+          else
+            SectionName = "";
+          SectionName += ".literal";
+          SectionName += CSectionName.substr(Pos + 5);
+        } else {
+          SectionName = CSectionName;
+          SectionName += ".literal";
+        }
+
+        MCSectionELF *S =
+            OutContext.getELFSection(SectionName, ELF::SHT_PROGBITS,
+                                     ELF::SHF_EXECINSTR | ELF::SHF_ALLOC);
+        S->setAlignment(Align(4));
+        OutStreamer->switchSection(S);
+      }
+    }
+
+    if (CPE.isMachineConstantPoolEntry()) {
+      XtensaConstantPoolValue *ACPV =
+          static_cast<XtensaConstantPoolValue *>(CPE.Val.MachineCPVal);
+      ACPV->setLabelId(i);
+      emitMachineConstantPoolValue(CPE.Val.MachineCPVal);
+    } else {
+      MCSymbol *LblSym = GetCPISymbol(i);
+      // TODO find a better way to check whether we emit data to .s file
+      if (OutStreamer->hasRawTextSupport()) {
+        std::string str("\t.literal ");
+        str += LblSym->getName();
+        str += ", ";
+        const Constant *C = CPE.Val.ConstVal;
+
+        Type *Ty = C->getType();
+        if (const auto *CFP = dyn_cast<ConstantFP>(C)) {
+          str += toString(CFP->getValueAPF().bitcastToAPInt(), 10, true);
+        } else if (const auto *CI = dyn_cast<ConstantInt>(C)) {
+          str += toString(CI->getValue(), 10, true);
+        } else if (isa<PointerType>(Ty)) {
+          const MCExpr *ME = lowerConstant(C);
+          const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*ME);
+          const MCSymbol &Sym = SRE.getSymbol();
+          str += Sym.getName();
+        } else {
+          unsigned NumElements;
+          if (isa<VectorType>(Ty))
+            NumElements = (cast<FixedVectorType>(Ty))->getNumElements();
+          else
+            NumElements = Ty->getArrayNumElements();
+
+          for (unsigned I = 0; I < NumElements; I++) {
+            const Constant *CAE = C->getAggregateElement(I);
+            if (I > 0)
+              str += ", ";
+            if (const auto *CFP = dyn_cast<ConstantFP>(CAE)) {
+              str += toString(CFP->getValueAPF().bitcastToAPInt(), 10, true);
+            } else if (const auto *CI = dyn_cast<ConstantInt>(CAE)) {
+              str += toString(CI->getValue(), 10, true);
+            }
+          }
+        }
+
+        OutStreamer->emitRawText(StringRef(str));
+      } else {
+        OutStreamer->emitLabel(LblSym);
+        emitGlobalConstant(getDataLayout(), CPE.Val.ConstVal);
+      }
+    }
+  }
+}
+
+void XtensaAsmPrinter::emitMachineConstantPoolValue(
+    MachineConstantPoolValue *MCPV) {
+  XtensaConstantPoolValue *ACPV = static_cast<XtensaConstantPoolValue *>(MCPV);
+
+  MCSymbol *MCSym;
+  if (ACPV->isBlockAddress()) {
+    const BlockAddress *BA =
+        cast<XtensaConstantPoolConstant>(ACPV)->getBlockAddress();
+    MCSym = GetBlockAddressSymbol(BA);
+  } else if (ACPV->isGlobalValue()) {
+    const GlobalValue *GV = cast<XtensaConstantPoolConstant>(ACPV)->getGV();
+    // TODO some modifiers
+    MCSym = getSymbol(GV);
+  } else if (ACPV->isMachineBasicBlock()) {
+    const MachineBasicBlock *MBB = cast<XtensaConstantPoolMBB>(ACPV)->getMBB();
+    MCSym = MBB->getSymbol();
+  } else if (ACPV->isJumpTable()) {
+    unsigned idx = cast<XtensaConstantPoolJumpTable>(ACPV)->getIndex();
+    MCSym = this->GetJTISymbol(idx, false);
+  } else {
+    assert(ACPV->isExtSymbol() && "unrecognized constant pool value");
+    XtensaConstantPoolSymbol *XtensaSym = cast<XtensaConstantPoolSymbol>(ACPV);
+    const char *Sym = XtensaSym->getSymbol();
+    // TODO it's a trick to distinguish static references and generated rodata
+    // references Some clear method required
+    {
+      std::string SymName(Sym);
+      if (XtensaSym->isPrivateLinkage())
+        SymName = ".L" + SymName;
+      MCSym = GetExternalSymbolSymbol(StringRef(SymName));
+    }
+  }
+
+  MCSymbol *LblSym = GetCPISymbol(ACPV->getLabelId());
+  // TODO find a better way to check whether we emit data to .s file
+  if (OutStreamer->hasRawTextSupport()) {
+    std::string SymName("\t.literal ");
+    SymName += LblSym->getName();
+    SymName += ", ";
+    SymName += MCSym->getName();
+
+    StringRef Modifier = ACPV->getModifierText();
+    SymName += Modifier;
+
+    OutStreamer->emitRawText(StringRef(SymName));
+  } else {
+    MCSymbolRefExpr::VariantKind VK =
+        getModifierVariantKind(ACPV->getModifier());
+
+    if (ACPV->getModifier() != XtensaCP::no_modifier) {
+      std::string SymName(MCSym->getName());
+      MCSym = GetExternalSymbolSymbol(StringRef(SymName));
+    }
+
+    const MCExpr *Expr = MCSymbolRefExpr::create(MCSym, VK, OutContext);
+    uint64_t Size = getDataLayout().getTypeAllocSize(ACPV->getType());
+    OutStreamer->emitLabel(LblSym);
+    OutStreamer->emitValue(Expr, Size);
+  }
+}
+
 // Force static initialization.
 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeXtensaAsmPrinter() {
   RegisterAsmPrinter<XtensaAsmPrinter> A(getTheXtensaTarget());
 }