GlobalsModRef+OptNone: Don't prove readnone/other properties from an optnone function

Seems like at least one reasonable interpretation of optnone is that the
optimizer never "looks inside" a function. This fix is consistent with
that interpretation.

Specifically this came up in the situation:

f3 calls f2 calls f1
f2 is always_inline
f1 is optnone

The application of readnone to f1 (& thus to f2) caused the inliner to
kill the call to f2 as being trivially dead (without even checking the
cost function, as it happens - not sure if that's also a bug).

llvm-svn: 304833

2 files changed, 42 insertions, 0 deletions

diff --git a/llvm/unittests/Analysis/CMakeLists.txt b/llvm/unittests/Analysis/CMakeLists.txt
index 8082c54b9c6..ac8bca25d93 100644
--- a/llvm/unittests/Analysis/CMakeLists.txt
+++ b/llvm/unittests/Analysis/CMakeLists.txt
@@ -12,6 +12,7 @@ add_llvm_unittest(AnalysisTests
   CallGraphTest.cpp
   CFGTest.cpp
   CGSCCPassManagerTest.cpp
+  GlobalsModRefTest.cpp
   LazyCallGraphTest.cpp
   LoopInfoTest.cpp
   MemoryBuiltinsTest.cpp
diff --git a/llvm/unittests/Analysis/GlobalsModRefTest.cpp b/llvm/unittests/Analysis/GlobalsModRefTest.cpp
new file mode 100644
index 00000000000..da8b44d273f
--- /dev/null
+++ b/llvm/unittests/Analysis/GlobalsModRefTest.cpp
@@ -0,0 +1,41 @@
+//===--- GlobalsModRefTest.cpp - Mixed TBAA unit tests --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/AsmParser/Parser.h"
+#include "llvm/Support/SourceMgr.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+TEST(GlobalsModRef, OptNone) {
+  StringRef Assembly = R"(
+    define void @f() optnone {
+      ret void
+    }
+  )";
+
+  LLVMContext Context;
+  SMDiagnostic Error;
+  auto M = parseAssemblyString(Assembly, Error, Context);
+  ASSERT_TRUE(M) << "Bad assembly?";
+
+  const auto &funcs = M->functions();
+  ASSERT_NE(funcs.begin(), funcs.end());
+  EXPECT_EQ(std::next(funcs.begin()), funcs.end());
+  const Function &F = *funcs.begin();
+
+  Triple Trip(M->getTargetTriple());
+  TargetLibraryInfoImpl TLII(Trip);
+  TargetLibraryInfo TLI(TLII);
+  llvm::CallGraph CG(*M);
+
+  auto AAR = GlobalsAAResult::analyzeModule(*M, TLI, CG);
+  EXPECT_EQ(FMRB_UnknownModRefBehavior, AAR.getModRefBehavior(&F));
+}