3 files changed, 63 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index cc9ed95be59..f68bac98564 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -105,6 +105,7 @@ add_llvm_library(LLVMCodeGen
   RegisterUsageInfo.cpp
   RegUsageInfoCollector.cpp
   RegUsageInfoPropagate.cpp
+  ResetMachineFunctionPass.cpp
   SafeStack.cpp
   SafeStackColoring.cpp
   SafeStackLayout.cpp
diff --git a/llvm/lib/CodeGen/LLVMTargetMachine.cpp b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
index 844e1ffe681..e11eb014111 100644
--- a/llvm/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
@@ -168,6 +168,15 @@ addPassesToGenerateCode(LLVMTargetMachine *TM, PassManagerBase &PM,
     if (PassConfig->addGlobalInstructionSelect())
       return nullptr;
 
+    // Pass to reset the MachineFunction if the ISel failed.
+    PM.add(createResetMachineFunctionPass());
+
+    // Provide a fallback path when we do not want to abort on
+    // not-yet-supported input.
+    if (LLVM_UNLIKELY(!PassConfig->isGlobalISelAbortEnabled()) &&
+        PassConfig->addInstSelector())
+      return nullptr;
+
   } else if (PassConfig->addInstSelector())
     return nullptr;
 
diff --git a/llvm/lib/CodeGen/ResetMachineFunctionPass.cpp b/llvm/lib/CodeGen/ResetMachineFunctionPass.cpp
new file mode 100644
index 00000000000..3b7729a0540
--- /dev/null
+++ b/llvm/lib/CodeGen/ResetMachineFunctionPass.cpp
@@ -0,0 +1,53 @@
+//===-- ResetMachineFunctionPass.cpp - Machine Loop Invariant Code Motion Pass ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/Support/Debug.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "reset-machine-function"
+
+namespace {
+  class ResetMachineFunction : public MachineFunctionPass {
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    ResetMachineFunction() :
+      MachineFunctionPass(ID) {
+    }
+
+    const char *getPassName() const override {
+      return "ResetMachineFunction";
+    }
+
+    bool runOnMachineFunction(MachineFunction &MF) override {
+      if (MF.getProperties().hasProperty(
+              MachineFunctionProperties::Property::FailedISel)) {
+        DEBUG(dbgs() << "Reseting: " << MF.getName() << '\n');
+        MF.reset();
+        return true;
+      }
+      return false;
+    }
+
+  };
+} // end anonymous namespace
+
+char ResetMachineFunction::ID = 0;
+INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
+                "reset machine function if ISel failed", false, false)
+
+MachineFunctionPass *
+llvm::createResetMachineFunctionPass() {
+  return new ResetMachineFunction();
+}