Revert "Re-land "[LTO] Enable module summary eission by default for regular LTO""

This reverts commit 8246e4314763066223547505fe18a288f639a475.

Change-Id: I1b25ac90f805d5c93fe227d5e6c25e2f54d0c1aa

6 files changed, 21 insertions, 63 deletions

diff --git a/include/clang/Basic/CodeGenOptions.def b/include/clang/Basic/CodeGenOptions.def
index a7aafcf2f4..2a8574e633 100644
--- a/include/clang/Basic/CodeGenOptions.def
+++ b/include/clang/Basic/CodeGenOptions.def
@@ -111,7 +111,7 @@ CODEGENOPT(LessPreciseFPMAD  , 1, 0) ///< Enable less precise MAD instructions t
                                      ///< be generated.
 CODEGENOPT(PrepareForLTO     , 1, 0) ///< Set when -flto is enabled on the
                                      ///< compile step.
-CODEGENOPT(PrepareForThinLTO , 1, 0) ///< Set when -flto=thin is enabled on the
+CODEGENOPT(EmitSummaryIndex, 1, 0)   ///< Set when -flto=thin is enabled on the
                                      ///< compile step.
 CODEGENOPT(LTOUnit, 1, 0) ///< Emit IR to support LTO unit features (CFI, whole
                           ///< program vtable opt).
diff --git a/lib/CodeGen/BackendUtil.cpp b/lib/CodeGen/BackendUtil.cpp
index e020187ba7..fe0be1dc4d 100644
--- a/lib/CodeGen/BackendUtil.cpp
+++ b/lib/CodeGen/BackendUtil.cpp
@@ -546,7 +546,7 @@ void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
     PMBuilder.Inliner = createFunctionInliningPass(
         CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
         (!CodeGenOpts.SampleProfileFile.empty() &&
-         CodeGenOpts.PrepareForThinLTO));
+         CodeGenOpts.EmitSummaryIndex));
   }
 
   PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
@@ -556,7 +556,7 @@ void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
 
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
-  PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
+  PMBuilder.PrepareForThinLTO = CodeGenOpts.EmitSummaryIndex;
   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
@@ -810,7 +810,7 @@ void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
     break;
 
   case Backend_EmitBC:
-    if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
+    if (CodeGenOpts.EmitSummaryIndex && !CodeGenOpts.DisableLLVMPasses) {
       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
         if (!ThinLinkOS)
@@ -820,24 +820,10 @@ void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
                                CodeGenOpts.EnableSplitLTOUnit);
       PerModulePasses.add(createWriteThinLTOBitcodePass(
           *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
-    } else {
-      // Emit a module summary by default for Regular LTO except for ld64
-      // targets
-      bool EmitLTOSummary =
-          (CodeGenOpts.PrepareForLTO &&
-           !CodeGenOpts.DisableLLVMPasses &&
-           llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
-               llvm::Triple::Apple);
-      if (EmitLTOSummary) {
-        if (!TheModule->getModuleFlag("ThinLTO"))
-          TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
-        TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
-                                 CodeGenOpts.EnableSplitLTOUnit);
-      }
-
-      PerModulePasses.add(createBitcodeWriterPass(
-          *OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
     }
+    else
+      PerModulePasses.add(
+          createBitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists));
     break;
 
   case Backend_EmitLL:
@@ -1000,7 +986,7 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
   ModulePassManager MPM(CodeGenOpts.DebugPassManager);
 
   if (!CodeGenOpts.DisableLLVMPasses) {
-    bool IsThinLTO = CodeGenOpts.PrepareForThinLTO;
+    bool IsThinLTO = CodeGenOpts.EmitSummaryIndex;
     bool IsLTO = CodeGenOpts.PrepareForLTO;
 
     if (CodeGenOpts.OptimizationLevel == 0) {
@@ -1015,11 +1001,9 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
         MPM.addPass(createModuleToFunctionPassAdaptor(BoundsCheckingPass()));
 
-      // Lastly, add semantically necessary passes for LTO.
-      if (IsLTO || IsThinLTO) {
-        MPM.addPass(CanonicalizeAliasesPass());
+      // Lastly, add a semantically necessary pass for ThinLTO.
+      if (IsThinLTO)
         MPM.addPass(NameAnonGlobalPass());
-      }
     } else {
       // Map our optimization levels into one of the distinct levels used to
       // configure the pipeline.
@@ -1057,7 +1041,6 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
         MPM = PB.buildLTOPreLinkDefaultPipeline(Level,
                                                 CodeGenOpts.DebugPassManager);
         MPM.addPass(CanonicalizeAliasesPass());
-        MPM.addPass(NameAnonGlobalPass());
       } else {
         MPM = PB.buildPerModuleDefaultPipeline(Level,
                                                CodeGenOpts.DebugPassManager);
@@ -1077,7 +1060,7 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
     break;
 
   case Backend_EmitBC:
-    if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
+    if (CodeGenOpts.EmitSummaryIndex && !CodeGenOpts.DisableLLVMPasses) {
       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
         if (!ThinLinkOS)
@@ -1088,21 +1071,9 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
       MPM.addPass(ThinLTOBitcodeWriterPass(*OS, ThinLinkOS ? &ThinLinkOS->os()
                                                            : nullptr));
     } else {
-      // Emit a module summary by default for Regular LTO except for ld64
-      // targets
-      bool EmitLTOSummary =
-          (CodeGenOpts.PrepareForLTO &&
-           !CodeGenOpts.DisableLLVMPasses &&
-           llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
-               llvm::Triple::Apple);
-      if (EmitLTOSummary) {
-        if (!TheModule->getModuleFlag("ThinLTO"))
-          TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
-        TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
-                                 CodeGenOpts.EnableSplitLTOUnit);
-      }
-      MPM.addPass(
-          BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
+      MPM.addPass(BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists,
+                                    CodeGenOpts.EmitSummaryIndex,
+                                    CodeGenOpts.EmitSummaryIndex));
     }
     break;
 
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index ce48f8bb13..5e17f5dc69 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -608,7 +608,7 @@ void CGDebugInfo::CreateCompileUnit() {
   // Create new compile unit.
   TheCU = DBuilder.createCompileUnit(
       LangTag, CUFile, CGOpts.EmitVersionIdentMetadata ? Producer : "",
-      LO.Optimize || CGOpts.PrepareForLTO || CGOpts.PrepareForThinLTO,
+      LO.Optimize || CGOpts.PrepareForLTO || CGOpts.EmitSummaryIndex,
       CGOpts.DwarfDebugFlags, RuntimeVers,
       (CGOpts.getSplitDwarfMode() != CodeGenOptions::NoFission)
           ? ""
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index bda8427b1a..41a01f37ce 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -898,11 +898,11 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.ProfileSampleAccurate = Args.hasArg(OPT_fprofile_sample_accurate);
 
   Opts.PrepareForLTO = Args.hasArg(OPT_flto, OPT_flto_EQ);
-  Opts.PrepareForThinLTO = false;
+  Opts.EmitSummaryIndex = false;
   if (Arg *A = Args.getLastArg(OPT_flto_EQ)) {
     StringRef S = A->getValue();
     if (S == "thin")
-      Opts.PrepareForThinLTO = true;
+      Opts.EmitSummaryIndex = true;
     else if (S != "full")
       Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << S;
   }
diff --git a/test/CodeGen/emit-summary-index.c b/test/CodeGen/emit-summary-index.c
deleted file mode 100644
index 6126410206..0000000000
--- a/test/CodeGen/emit-summary-index.c
+++ /dev/null
@@ -1,17 +0,0 @@
-// ; Check that the -flto=thin option emits a ThinLTO summary
-// RUN: %clang_cc1 -flto=thin -emit-llvm-bc < %s | llvm-bcanalyzer -dump | FileCheck %s
-// CHECK: <GLOBALVAL_SUMMARY_BLOCK
-//
-// ; Check that we do not emit a summary for regular LTO on Apple platforms
-// RUN: %clang_cc1 -flto -triple x86_64-apple-darwin -emit-llvm-bc < %s | llvm-bcanalyzer -dump | FileCheck --check-prefix=LTO %s
-// LTO-NOT: GLOBALVAL_SUMMARY_BLOCK
-//
-// ; Check that we emit a summary for regular LTO by default elsewhere
-// RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm-bc < %s | llvm-bcanalyzer -dump | FileCheck --check-prefix=LTOINDEX %s
-// LTOINDEX: <FULL_LTO_GLOBALVAL_SUMMARY_BLOCK
-//
-// ; Simulate -save-temps and check that it works (!"ThinLTO" module flag not added multiple times)
-// RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm-bc -disable-llvm-passes < %s -o %t.bc
-// RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm-bc -x ir < %t.bc | llvm-bcanalyzer -dump | FileCheck --check-prefix=LTOINDEX %s
-
-int main() {}
diff --git a/test/Misc/thinlto.c b/test/Misc/thinlto.c
new file mode 100644
index 0000000000..ec0f03f5a2
--- /dev/null
+++ b/test/Misc/thinlto.c
@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -flto=thin -emit-llvm-bc < %s | llvm-bcanalyzer -dump | FileCheck %s
+// ; Check that the -flto=thin option emits a summary
+// CHECK: <GLOBALVAL_SUMMARY_BLOCK
+int main() {}