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//===-- WebAssemblyCallIndirectFixup.cpp - Fix call_indirects -------------===//
//
// 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 converts pseudo call_indirect instructions into real
/// call_indirects.
///
/// The order of arguments for a call_indirect is the arguments to the function
/// call, followed by the function pointer. There's no natural way to express
/// a machineinstr with varargs followed by one more arg, so we express it as
/// the function pointer followed by varargs, then rewrite it here.
///
/// We need to rewrite the order of the arguments on the machineinstrs
/// themselves so that register stackification knows the order they'll be
/// executed in.
///
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h" // for WebAssembly::ARGUMENT_*
#include "WebAssembly.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblySubtarget.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "wasm-call-indirect-fixup"
namespace {
class WebAssemblyCallIndirectFixup final : public MachineFunctionPass {
StringRef getPassName() const override {
return "WebAssembly CallIndirect Fixup";
}
bool runOnMachineFunction(MachineFunction &MF) override;
public:
static char ID; // Pass identification, replacement for typeid
WebAssemblyCallIndirectFixup() : MachineFunctionPass(ID) {}
};
} // end anonymous namespace
char WebAssemblyCallIndirectFixup::ID = 0;
FunctionPass *llvm::createWebAssemblyCallIndirectFixup() {
return new WebAssemblyCallIndirectFixup();
}
static unsigned GetNonPseudoCallIndirectOpcode(const MachineInstr &MI) {
switch (MI.getOpcode()) {
using namespace WebAssembly;
case PCALL_INDIRECT_VOID: return CALL_INDIRECT_VOID;
case PCALL_INDIRECT_I32: return CALL_INDIRECT_I32;
case PCALL_INDIRECT_I64: return CALL_INDIRECT_I64;
case PCALL_INDIRECT_F32: return CALL_INDIRECT_F32;
case PCALL_INDIRECT_F64: return CALL_INDIRECT_F64;
case PCALL_INDIRECT_v16i8: return CALL_INDIRECT_v16i8;
case PCALL_INDIRECT_v8i16: return CALL_INDIRECT_v8i16;
case PCALL_INDIRECT_v4i32: return CALL_INDIRECT_v4i32;
case PCALL_INDIRECT_v4f32: return CALL_INDIRECT_v4f32;
default: return INSTRUCTION_LIST_END;
}
}
static bool IsPseudoCallIndirect(const MachineInstr &MI) {
return GetNonPseudoCallIndirectOpcode(MI) !=
WebAssembly::INSTRUCTION_LIST_END;
}
bool WebAssemblyCallIndirectFixup::runOnMachineFunction(MachineFunction &MF) {
DEBUG(dbgs() << "********** Fixing up CALL_INDIRECTs **********\n"
<< MF.getName() << '\n');
bool Changed = false;
const WebAssemblyInstrInfo *TII =
MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
for (MachineBasicBlock &MBB : MF) {
for (MachineInstr &MI : MBB) {
if (IsPseudoCallIndirect(MI)) {
DEBUG(dbgs() << "Found call_indirect: " << MI << '\n');
// Rewrite pseudo to non-pseudo
const MCInstrDesc &Desc = TII->get(GetNonPseudoCallIndirectOpcode(MI));
MI.setDesc(Desc);
// Rewrite argument order
SmallVector<MachineOperand, 8> Ops;
// Set up a placeholder for the type signature immediate.
Ops.push_back(MachineOperand::CreateImm(0));
// Set up the flags immediate, which currently has no defined flags
// so it's always zero.
Ops.push_back(MachineOperand::CreateImm(0));
for (const MachineOperand &MO :
make_range(MI.operands_begin() +
MI.getDesc().getNumDefs() + 1,
MI.operands_begin() +
MI.getNumExplicitOperands()))
Ops.push_back(MO);
Ops.push_back(MI.getOperand(MI.getDesc().getNumDefs()));
// Replace the instructions operands.
while (MI.getNumOperands() > MI.getDesc().getNumDefs())
MI.RemoveOperand(MI.getNumOperands() - 1);
for (const MachineOperand &MO : Ops)
MI.addOperand(MO);
DEBUG(dbgs() << " After transform: " << MI);
Changed = true;
}
}
}
DEBUG(dbgs() << "\nDone fixing up CALL_INDIRECTs\n\n");
return Changed;
}
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