84 lines
3.0 KiB
C++
84 lines
3.0 KiB
C++
//===-- WebAssemblyEHRestoreStackPointer.cpp - __stack_pointer restoration ===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
///
|
|
/// \file
|
|
/// After the stack is unwound due to a thrown exception, the __stack_pointer
|
|
/// global can point to an invalid address. This inserts instructions that
|
|
/// restore __stack_pointer global.
|
|
///
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
|
|
#include "WebAssembly.h"
|
|
#include "WebAssemblySubtarget.h"
|
|
#include "WebAssemblyUtilities.h"
|
|
#include "llvm/CodeGen/MachineFrameInfo.h"
|
|
#include "llvm/MC/MCAsmInfo.h"
|
|
using namespace llvm;
|
|
|
|
#define DEBUG_TYPE "wasm-eh-restore-stack-pointer"
|
|
|
|
namespace {
|
|
class WebAssemblyEHRestoreStackPointer final : public MachineFunctionPass {
|
|
public:
|
|
static char ID; // Pass identification, replacement for typeid
|
|
WebAssemblyEHRestoreStackPointer() : MachineFunctionPass(ID) {}
|
|
|
|
StringRef getPassName() const override {
|
|
return "WebAssembly Restore Stack Pointer for Exception Handling";
|
|
}
|
|
|
|
void getAnalysisUsage(AnalysisUsage &AU) const override {
|
|
AU.setPreservesCFG();
|
|
MachineFunctionPass::getAnalysisUsage(AU);
|
|
}
|
|
|
|
bool runOnMachineFunction(MachineFunction &MF) override;
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
char WebAssemblyEHRestoreStackPointer::ID = 0;
|
|
INITIALIZE_PASS(WebAssemblyEHRestoreStackPointer, DEBUG_TYPE,
|
|
"Restore Stack Pointer for Exception Handling", true, false)
|
|
|
|
FunctionPass *llvm::createWebAssemblyEHRestoreStackPointer() {
|
|
return new WebAssemblyEHRestoreStackPointer();
|
|
}
|
|
|
|
bool WebAssemblyEHRestoreStackPointer::runOnMachineFunction(
|
|
MachineFunction &MF) {
|
|
const auto *FrameLowering = static_cast<const WebAssemblyFrameLowering *>(
|
|
MF.getSubtarget().getFrameLowering());
|
|
if (!FrameLowering->needsPrologForEH(MF))
|
|
return false;
|
|
bool Changed = false;
|
|
|
|
for (auto &MBB : MF) {
|
|
if (!MBB.isEHPad())
|
|
continue;
|
|
Changed = true;
|
|
|
|
// Insert __stack_pointer restoring instructions at the beginning of each EH
|
|
// pad, after the catch instruction. (Catch instructions may have been
|
|
// reordered, and catch_all instructions have not been inserted yet, but
|
|
// those cases are handled in LateEHPrepare).
|
|
//
|
|
// Here it is safe to assume that SP32 holds the latest value of
|
|
// __stack_pointer, because the only exception for this case is when a
|
|
// function uses the red zone, but that only happens with leaf functions,
|
|
// and we don't restore __stack_pointer in leaf functions anyway.
|
|
auto InsertPos = MBB.begin();
|
|
if (WebAssembly::isCatch(*MBB.begin()))
|
|
InsertPos++;
|
|
FrameLowering->writeSPToGlobal(WebAssembly::SP32, MF, MBB, InsertPos,
|
|
MBB.begin()->getDebugLoc());
|
|
}
|
|
return Changed;
|
|
}
|