IPO: Add use-list-order verifier

Add a -verify-use-list-order pass, which shuffles use-list order, writes
to bitcode, reads back, and verifies that the (shuffled) order matches.

  - The utility functions live in lib/IR/UseListOrder.cpp.

  - Moved (and renamed) the command-line option to enable writing
    use-lists, so that this pass can return early if the use-list orders
    aren't being serialized.

It's not clear that this pass is the right direction long-term (perhaps
a separate tool instead?), but short-term it's a great way to test the
use-list order prototype.  I've added an XFAIL-ed testcase that I'm
hoping to get working pretty quickly.

This is part of PR5680.

llvm-svn: 213945

3 files changed, 63 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/IPO/CMakeLists.txt b/llvm/lib/Transforms/IPO/CMakeLists.txt
index 90c1c33e6dc..070ecfdc143 100644
--- a/llvm/lib/Transforms/IPO/CMakeLists.txt
+++ b/llvm/lib/Transforms/IPO/CMakeLists.txt
@@ -20,6 +20,7 @@ add_llvm_library(LLVMipo
   PruneEH.cpp
   StripDeadPrototypes.cpp
   StripSymbols.cpp
+  VerifyUseListOrder.cpp
   )
 
 add_dependencies(LLVMipo intrinsics_gen)
diff --git a/llvm/lib/Transforms/IPO/IPO.cpp b/llvm/lib/Transforms/IPO/IPO.cpp
index b4d31d8d6fc..5dce2d6b407 100644
--- a/llvm/lib/Transforms/IPO/IPO.cpp
+++ b/llvm/lib/Transforms/IPO/IPO.cpp
@@ -44,6 +44,7 @@ void llvm::initializeIPO(PassRegistry &Registry) {
   initializeStripDebugDeclarePass(Registry);
   initializeStripDeadDebugInfoPass(Registry);
   initializeStripNonDebugSymbolsPass(Registry);
+  initializeVerifyUseListOrderPass(Registry);
   initializeBarrierNoopPass(Registry);
 }
 
diff --git a/llvm/lib/Transforms/IPO/VerifyUseListOrder.cpp b/llvm/lib/Transforms/IPO/VerifyUseListOrder.cpp
new file mode 100644
index 00000000000..a48f6c78202
--- /dev/null
+++ b/llvm/lib/Transforms/IPO/VerifyUseListOrder.cpp
@@ -0,0 +1,61 @@
+//===- VerifyUseListOrder.cpp - Use List Order Verifier ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Pass to verify use-list order doesn't change after serialization.
+//
+// Despite it being a verifier, this pass *does* transform the module, since it
+// shuffles the use-list of every value.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO.h"
+#include "llvm/IR/UseListOrder.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "use-list-order"
+
+namespace {
+class VerifyUseListOrder : public ModulePass {
+public:
+  static char ID;
+  VerifyUseListOrder();
+  bool runOnModule(Module &M) override;
+};
+} // end anonymous namespace
+
+char VerifyUseListOrder::ID = 0;
+INITIALIZE_PASS(VerifyUseListOrder, "verify-use-list-order",
+                "Verify Use List Order", false, false)
+VerifyUseListOrder::VerifyUseListOrder() : ModulePass(ID) {
+  initializeVerifyUseListOrderPass(*PassRegistry::getPassRegistry());
+}
+
+bool VerifyUseListOrder::runOnModule(Module &M) {
+  DEBUG(dbgs() << "*** verify-use-list-order ***\n");
+  if (!shouldPreserveBitcodeUseListOrder()) {
+    // Can't verify if order isn't preserved.
+    DEBUG(dbgs() << "warning: cannot verify bitcode; "
+                    "try -preserve-bc-use-list-order\n");
+    return false;
+  }
+
+  shuffleUseLists(M);
+  if (!verifyBitcodeUseListOrder(M))
+    report_fatal_error("bitcode use-list order changed");
+
+  return true;
+}
+
+ModulePass *llvm::createVerifyUseListOrderPass() {
+  return new VerifyUseListOrder;
+}