[ThinLTO] Enable ThinLTO WholeProgramDevirt and LowerTypeTests in new PM

Summary:
Enable these passes for CFI and WPD in ThinLTO and LTO with the new pass
manager. Add a couple of tests for both PMs based on the clang tests
tools/clang/test/CodeGen/thinlto-distributed-cfi*.ll, but just test
through llvm-lto2 and not with distributed ThinLTO.

Reviewers: pcc

Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D49429

llvm-svn: 337461

1 files changed, 32 insertions, 19 deletions

diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index d4d66e06a02..eb04dcc8b6e 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -922,15 +922,28 @@ PassBuilder::buildThinLTOPreLinkDefaultPipeline(OptimizationLevel Level,
   return MPM;
 }
 
-ModulePassManager
-PassBuilder::buildThinLTODefaultPipeline(OptimizationLevel Level,
-                                         bool DebugLogging) {
-  // FIXME: The summary index is not hooked in the new pass manager yet.
-  // When it's going to be hooked, enable WholeProgramDevirt and LowerTypeTest
-  // here.
-
+ModulePassManager PassBuilder::buildThinLTODefaultPipeline(
+    OptimizationLevel Level, bool DebugLogging,
+    const ModuleSummaryIndex *ImportSummary) {
   ModulePassManager MPM(DebugLogging);
 
+  if (ImportSummary) {
+    // These passes import type identifier resolutions for whole-program
+    // devirtualization and CFI. They must run early because other passes may
+    // disturb the specific instruction patterns that these passes look for,
+    // creating dependencies on resolutions that may not appear in the summary.
+    //
+    // For example, GVN may transform the pattern assume(type.test) appearing in
+    // two basic blocks into assume(phi(type.test, type.test)), which would
+    // transform a dependency on a WPD resolution into a dependency on a type
+    // identifier resolution for CFI.
+    //
+    // Also, WPD has access to more precise information than ICP and can
+    // devirtualize more effectively, so it should operate on the IR first.
+    MPM.addPass(WholeProgramDevirtPass(nullptr, ImportSummary));
+    MPM.addPass(LowerTypeTestsPass(nullptr, ImportSummary));
+  }
+
   // Force any function attributes we want the rest of the pipeline to observe.
   MPM.addPass(ForceFunctionAttrsPass());
 
@@ -961,8 +974,9 @@ PassBuilder::buildLTOPreLinkDefaultPipeline(OptimizationLevel Level,
   return buildPerModuleDefaultPipeline(Level, DebugLogging);
 }
 
-ModulePassManager PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
-                                                       bool DebugLogging) {
+ModulePassManager
+PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level, bool DebugLogging,
+                                     ModuleSummaryIndex *ExportSummary) {
   assert(Level != O0 && "Must request optimizations for the default pipeline!");
   ModulePassManager MPM(DebugLogging);
 
@@ -1012,11 +1026,15 @@ ModulePassManager PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
 
   // Run whole program optimization of virtual call when the list of callees
   // is fixed.
-  MPM.addPass(WholeProgramDevirtPass());
+  MPM.addPass(WholeProgramDevirtPass(ExportSummary, nullptr));
 
   // Stop here at -O1.
-  if (Level == 1)
+  if (Level == 1) {
+    // The LowerTypeTestsPass needs to run to lower type metadata and the
+    // type.test intrinsics. The pass does nothing if CFI is disabled.
+    MPM.addPass(LowerTypeTestsPass(ExportSummary, nullptr));
     return MPM;
+  }
 
   // Optimize globals to try and fold them into constants.
   MPM.addPass(GlobalOptPass());
@@ -1125,12 +1143,7 @@ ModulePassManager PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
   // clang's control flow integrity mechanisms (-fsanitize=cfi*) and needs
   // to be run at link time if CFI is enabled. This pass does nothing if
   // CFI is disabled.
-  // Enable once we add support for the summary in the new PM.
-#if 0
-  MPM.addPass(LowerTypeTestsPass(Summary ? PassSummaryAction::Export :
-                                           PassSummaryAction::None,
-                                Summary));
-#endif
+  MPM.addPass(LowerTypeTestsPass(ExportSummary, nullptr));
 
   // Add late LTO optimization passes.
   // Delete basic blocks, which optimization passes may have killed.
@@ -1442,12 +1455,12 @@ bool PassBuilder::parseModulePass(ModulePassManager &MPM,
     } else if (Matches[1] == "thinlto-pre-link") {
       MPM.addPass(buildThinLTOPreLinkDefaultPipeline(L, DebugLogging));
     } else if (Matches[1] == "thinlto") {
-      MPM.addPass(buildThinLTODefaultPipeline(L, DebugLogging));
+      MPM.addPass(buildThinLTODefaultPipeline(L, DebugLogging, nullptr));
     } else if (Matches[1] == "lto-pre-link") {
       MPM.addPass(buildLTOPreLinkDefaultPipeline(L, DebugLogging));
     } else {
       assert(Matches[1] == "lto" && "Not one of the matched options!");
-      MPM.addPass(buildLTODefaultPipeline(L, DebugLogging));
+      MPM.addPass(buildLTODefaultPipeline(L, DebugLogging, nullptr));
     }
     return true;
   }