[LTO] Enable module summary emission by default for regular LTO

Summary:
With D33921, we gained the ability to have module summaries in regular
LTO modules without triggering ThinLTO compilation. Module summaries in
regular LTO allow garbage collection (dead stripping) before LTO
compilation and thus open up additional optimization opportunities.

This patch enables summary emission in regular LTO for all targets
except ld64-based ones (which use the legacy LTO API).

Reviewers: pcc, tejohnson, mehdi_amini

Subscribers: inglorion, eraman, cfe-commits

Differential Revision: https://reviews.llvm.org/D34156

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@335284 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Frontend/CodeGenOptions.def b/include/clang/Frontend/CodeGenOptions.def
index 019425d1946afba4f13c284d4d3e196337933526..99567e04ba6d65d43f66f82e46873fbd2dcfefd9 100644 (file)
--- a/include/clang/Frontend/CodeGenOptions.def
+++ b/include/clang/Frontend/CodeGenOptions.def
@@ -110,7 +110,7 @@ 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(EmitSummaryIndex, 1, 0)   ///< Set when -flto=thin is enabled on the
+CODEGENOPT(PrepareForThinLTO , 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 4125d507a1ee09463655f83d582e536fe585df63..b06c68fe742eb39207e1b4ed964ca306d9bbeb31 100644 (file)
--- a/lib/CodeGen/BackendUtil.cpp
+++ b/lib/CodeGen/BackendUtil.cpp
@@ -524,7 +524,7 @@ void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
     PMBuilder.Inliner = createFunctionInliningPass(
         CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
         (!CodeGenOpts.SampleProfileFile.empty() &&
-         CodeGenOpts.EmitSummaryIndex));
+         CodeGenOpts.PrepareForThinLTO));
   }
 
   PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
@@ -534,7 +534,7 @@ void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
 
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
-  PMBuilder.PrepareForThinLTO = CodeGenOpts.EmitSummaryIndex;
+  PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
@@ -776,7 +776,7 @@ void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
     break;
 
   case Backend_EmitBC:
-    if (CodeGenOpts.EmitSummaryIndex) {
+    if (CodeGenOpts.PrepareForThinLTO) {
       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
         if (!ThinLinkOS)
@@ -784,10 +784,20 @@ void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
       }
       PerModulePasses.add(createWriteThinLTOBitcodePass(
           *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
-    }
-    else
+    } else {
+      // Emit a module summary by default for Regular LTO except for ld64
+      // targets
+      bool EmitLTOSummary =
+          (CodeGenOpts.PrepareForLTO &&
+           llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
+               llvm::Triple::Apple);
+      if (EmitLTOSummary && !TheModule->getModuleFlag("ThinLTO"))
+        TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
+
       PerModulePasses.add(
-          createBitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists));
+          createBitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists,
+                                  EmitLTOSummary));
+    }
     break;
 
   case Backend_EmitLL:
@@ -935,7 +945,7 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
   ModulePassManager MPM(CodeGenOpts.DebugPassManager);
 
   if (!CodeGenOpts.DisableLLVMPasses) {
-    bool IsThinLTO = CodeGenOpts.EmitSummaryIndex;
+    bool IsThinLTO = CodeGenOpts.PrepareForThinLTO;
     bool IsLTO = CodeGenOpts.PrepareForLTO;
 
     if (CodeGenOpts.OptimizationLevel == 0) {
@@ -996,7 +1006,7 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
     break;
 
   case Backend_EmitBC:
-    if (CodeGenOpts.EmitSummaryIndex) {
+    if (CodeGenOpts.PrepareForThinLTO) {
       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
         if (!ThinLinkOS)
@@ -1005,9 +1015,17 @@ 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 &&
+           llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
+               llvm::Triple::Apple);
+      if (EmitLTOSummary && !TheModule->getModuleFlag("ThinLTO"))
+        TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
+
       MPM.addPass(BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists,
-                                    CodeGenOpts.EmitSummaryIndex,
-                                    CodeGenOpts.EmitSummaryIndex));
+                                    EmitLTOSummary));
     }
     break;
 

diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 3ca6459a6a33f05c86349f542fca14139032ed7f..a0d5fd62360e4688540e23e7899a237a3d45751d 100644 (file)
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -578,7 +578,7 @@ void CGDebugInfo::CreateCompileUnit() {
                           CSInfo,
                           getSource(SM, SM.getMainFileID())),
       CGOpts.EmitVersionIdentMetadata ? Producer : "",
-      LO.Optimize || CGOpts.PrepareForLTO || CGOpts.EmitSummaryIndex,
+      LO.Optimize || CGOpts.PrepareForLTO || CGOpts.PrepareForThinLTO,
       CGOpts.DwarfDebugFlags, RuntimeVers,
       CGOpts.EnableSplitDwarf ? "" : CGOpts.SplitDwarfFile, EmissionKind,
       0 /* DWOid */, CGOpts.SplitDwarfInlining, CGOpts.DebugInfoForProfiling,

diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 1f9d6b0d7f5cc88145cbfb80396d12ba47d83f0d..60ed5fdf708f0057a362b2cea766435e6b895522 100644 (file)
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -749,11 +749,11 @@ 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.EmitSummaryIndex = false;
+  Opts.PrepareForThinLTO = false;
   if (Arg *A = Args.getLastArg(OPT_flto_EQ)) {
     StringRef S = A->getValue();
     if (S == "thin")
-      Opts.EmitSummaryIndex = true;
+      Opts.PrepareForThinLTO = 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
new file mode 100644 (file)
index 0000000..6126410
--- /dev/null
+++ b/test/CodeGen/emit-summary-index.c
@@ -0,0 +1,17 @@
+// ; 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
deleted file mode 100644 (file)
index ec0f03f..0000000
--- a/test/Misc/thinlto.c
+++ /dev/null
@@ -1,4 +0,0 @@
-// 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() {}