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llvm-mirror/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
Derek Schuff f7c3e9132b [WebAssembly] Use LEB encoding for value types 
Previously we were using the encoded LEB hex values
for the value types.  This change uses the decoded
negative value and the LEB encoder to write them out.

Differential Revision: https://reviews.llvm.org/D30847

Patch by Sam Clegg

llvm-svn: 297777
2017-03-14 20:23:22 +00:00

238 lines
8.4 KiB
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// WebAssemblyMCInstLower.cpp - Convert WebAssembly MachineInstr to an MCInst //
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief This file contains code to lower WebAssembly MachineInstrs to their
/// corresponding MCInst records.
///
//===----------------------------------------------------------------------===//
#include "WebAssemblyMCInstLower.h"
#include "WebAssemblyAsmPrinter.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblyRuntimeLibcallSignatures.h"
#include "WebAssemblyUtilities.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/IR/Constants.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSymbolELF.h"
#include "llvm/MC/MCSymbolWasm.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
MCSymbol *
WebAssemblyMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
const GlobalValue *Global = MO.getGlobal();
MCSymbol *Sym = Printer.getSymbol(Global);
if (isa<MCSymbolELF>(Sym))
return Sym;
MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Sym);
if (const auto *FuncTy = dyn_cast<FunctionType>(Global->getValueType())) {
const MachineFunction &MF = *MO.getParent()->getParent()->getParent();
const TargetMachine &TM = MF.getTarget();
const Function &CurrentFunc = *MF.getFunction();
SmallVector<wasm::ValType, 4> Returns;
SmallVector<wasm::ValType, 4> Params;
wasm::ValType iPTR =
MF.getSubtarget<WebAssemblySubtarget>().hasAddr64() ?
wasm::ValType::I64 :
wasm::ValType::I32;
SmallVector<MVT, 4> ResultMVTs;
ComputeLegalValueVTs(CurrentFunc, TM, FuncTy->getReturnType(), ResultMVTs);
// WebAssembly can't currently handle returning tuples.
if (ResultMVTs.size() <= 1)
for (MVT ResultMVT : ResultMVTs)
Returns.push_back(WebAssembly::toValType(ResultMVT));
else
Params.push_back(iPTR);
for (Type *Ty : FuncTy->params()) {
SmallVector<MVT, 4> ParamMVTs;
ComputeLegalValueVTs(CurrentFunc, TM, Ty, ParamMVTs);
for (MVT ParamMVT : ParamMVTs)
Params.push_back(WebAssembly::toValType(ParamMVT));
}
if (FuncTy->isVarArg())
Params.push_back(iPTR);
WasmSym->setReturns(std::move(Returns));
WasmSym->setParams(std::move(Params));
WasmSym->setIsFunction(true);
}
return WasmSym;
}
MCSymbol *WebAssemblyMCInstLower::GetExternalSymbolSymbol(
const MachineOperand &MO) const {
const char *Name = MO.getSymbolName();
MCSymbol *Sym = Printer.GetExternalSymbolSymbol(Name);
if (isa<MCSymbolELF>(Sym))
return Sym;
MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Sym);
const WebAssemblySubtarget &Subtarget = Printer.getSubtarget();
// __stack_pointer is a global variable; all other external symbols used by
// CodeGen are functions.
if (strcmp(Name, "__stack_pointer") == 0)
return WasmSym;
SmallVector<wasm::ValType, 4> Returns;
SmallVector<wasm::ValType, 4> Params;
GetSignature(Subtarget, Name, Returns, Params);
WasmSym->setReturns(std::move(Returns));
WasmSym->setParams(std::move(Params));
WasmSym->setIsFunction(true);
return WasmSym;
}
MCOperand WebAssemblyMCInstLower::LowerSymbolOperand(MCSymbol *Sym,
int64_t Offset,
bool IsFunc) const {
MCSymbolRefExpr::VariantKind VK =
IsFunc ? MCSymbolRefExpr::VK_WebAssembly_FUNCTION
: MCSymbolRefExpr::VK_None;
if (!isa<MCSymbolELF>(Sym))
cast<MCSymbolWasm>(Sym)->setIsFunction(IsFunc);
const MCExpr *Expr = MCSymbolRefExpr::create(Sym, VK, Ctx);
if (Offset != 0) {
if (IsFunc)
report_fatal_error("Function addresses with offsets not supported");
Expr =
MCBinaryExpr::createAdd(Expr, MCConstantExpr::create(Offset, Ctx), Ctx);
}
return MCOperand::createExpr(Expr);
}
// Return the WebAssembly type associated with the given register class.
static wasm::ValType getType(const TargetRegisterClass *RC) {
if (RC == &WebAssembly::I32RegClass)
return wasm::ValType::I32;
if (RC == &WebAssembly::I64RegClass)
return wasm::ValType::I64;
if (RC == &WebAssembly::F32RegClass)
return wasm::ValType::F32;
if (RC == &WebAssembly::F64RegClass)
return wasm::ValType::F64;
llvm_unreachable("Unexpected register class");
}
void WebAssemblyMCInstLower::Lower(const MachineInstr *MI,
MCInst &OutMI) const {
OutMI.setOpcode(MI->getOpcode());
const MCInstrDesc &Desc = MI->getDesc();
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
MCOperand MCOp;
switch (MO.getType()) {
default:
MI->print(errs());
llvm_unreachable("unknown operand type");
case MachineOperand::MO_MachineBasicBlock:
MI->print(errs());
llvm_unreachable("MachineBasicBlock operand should have been rewritten");
case MachineOperand::MO_Register: {
// Ignore all implicit register operands.
if (MO.isImplicit())
continue;
const WebAssemblyFunctionInfo &MFI =
*MI->getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>();
unsigned WAReg = MFI.getWAReg(MO.getReg());
MCOp = MCOperand::createReg(WAReg);
break;
}
case MachineOperand::MO_Immediate:
if (i < Desc.NumOperands) {
const MCOperandInfo &Info = Desc.OpInfo[i];
if (Info.OperandType == WebAssembly::OPERAND_TYPEINDEX) {
MCSymbol *Sym = Printer.createTempSymbol("typeindex");
if (!isa<MCSymbolELF>(Sym)) {
SmallVector<wasm::ValType, 4> Returns;
SmallVector<wasm::ValType, 4> Params;
const MachineRegisterInfo &MRI =
MI->getParent()->getParent()->getRegInfo();
for (const MachineOperand &MO : MI->defs())
Returns.push_back(getType(MRI.getRegClass(MO.getReg())));
for (const MachineOperand &MO : MI->explicit_uses())
if (MO.isReg())
Params.push_back(getType(MRI.getRegClass(MO.getReg())));
// call_indirect instructions have a callee operand at the end which
// doesn't count as a param.
if (WebAssembly::isCallIndirect(*MI))
Params.pop_back();
MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Sym);
WasmSym->setReturns(std::move(Returns));
WasmSym->setParams(std::move(Params));
WasmSym->setIsFunction(true);
const MCExpr *Expr =
MCSymbolRefExpr::create(WasmSym,
MCSymbolRefExpr::VK_WebAssembly_TYPEINDEX,
Ctx);
MCOp = MCOperand::createExpr(Expr);
break;
}
}
}
MCOp = MCOperand::createImm(MO.getImm());
break;
case MachineOperand::MO_FPImmediate: {
// TODO: MC converts all floating point immediate operands to double.
// This is fine for numeric values, but may cause NaNs to change bits.
const ConstantFP *Imm = MO.getFPImm();
if (Imm->getType()->isFloatTy())
MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToFloat());
else if (Imm->getType()->isDoubleTy())
MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToDouble());
else
llvm_unreachable("unknown floating point immediate type");
break;
}
case MachineOperand::MO_GlobalAddress:
assert(MO.getTargetFlags() == 0 &&
"WebAssembly does not use target flags on GlobalAddresses");
MCOp = LowerSymbolOperand(GetGlobalAddressSymbol(MO), MO.getOffset(),
MO.getGlobal()->getValueType()->isFunctionTy());
break;
case MachineOperand::MO_ExternalSymbol:
// The target flag indicates whether this is a symbol for a
// variable or a function.
assert((MO.getTargetFlags() & -2) == 0 &&
"WebAssembly uses only one target flag bit on ExternalSymbols");
MCOp = LowerSymbolOperand(GetExternalSymbolSymbol(MO), /*Offset=*/0,
MO.getTargetFlags() & 1);
break;
}
OutMI.addOperand(MCOp);
}
}
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