[X86] Implement -mfentry

Summary: Insert calls to __fentry__ at function entry.

Reviewers: hfinkel, craig.topper

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D28000

llvm-svn: 293648

1 files changed, 55 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/FEntryInserter.cpp b/llvm/lib/CodeGen/FEntryInserter.cpp
new file mode 100644
index 00000000000..0759bf6713e
--- /dev/null
+++ b/llvm/lib/CodeGen/FEntryInserter.cpp
@@ -0,0 +1,55 @@
+//===-- FEntryInsertion.cpp - Patchable prologues for LLVM -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file edits function bodies to insert fentry calls.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Target/TargetFrameLowering.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+
+using namespace llvm;
+
+namespace {
+struct FEntryInserter : public MachineFunctionPass {
+  static char ID; // Pass identification, replacement for typeid
+  FEntryInserter() : MachineFunctionPass(ID) {
+    initializeFEntryInserterPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnMachineFunction(MachineFunction &F) override;
+};
+}
+
+bool FEntryInserter::runOnMachineFunction(MachineFunction &MF) {
+  const std::string FEntryName =
+      MF.getFunction()->getFnAttribute("fentry-call").getValueAsString();
+  if (FEntryName != "true")
+    return false;
+
+  auto &FirstMBB = *MF.begin();
+  auto &FirstMI = *FirstMBB.begin();
+
+  auto *TII = MF.getSubtarget().getInstrInfo();
+  BuildMI(FirstMBB, FirstMI, FirstMI.getDebugLoc(),
+          TII->get(TargetOpcode::FENTRY_CALL));
+  return true;
+}
+
+char FEntryInserter::ID = 0;
+char &llvm::FEntryInserterID = FEntryInserter::ID;
+INITIALIZE_PASS(FEntryInserter, "fentry-insert", "Insert fentry calls", false,
+                false)