[GlobalISel] Add a fallback path to SDISel.

When global-isel fails on a MachineFunction MF, MF will be cleaned up
and given to SDISel.
Thanks to this fallback, we can already perform correctness test even if
we support only a small portion of the functions in a test.

llvm-svn: 279891

1 files changed, 53 insertions, 0 deletions

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();
+}