[ThinLTO] Split NotEligibleToImport into legality and inlinability flags

Summary:
The NotEligibleToImport flag on the GlobalValueSummary was set if it
isn't legal to import (e.g. because it references unpromotable locals)
and when it can't be inlined (in which case importing is pointless).

I split out the inlinable piece into a separate flag on the
FunctionSummary (doesn't make sense for aliases or global variables),
because in the future we may want to import for reasons other than
inlining.

Reviewers: davidxl

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

Differential Revision: https://reviews.llvm.org/D53345

llvm-svn: 346261

9 files changed, 34 insertions, 12 deletions

diff --git a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
index 3eb150becfa..29b96ac746b 100644
--- a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
+++ b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -350,20 +350,18 @@ static void computeFunctionSummary(
 
   bool NonRenamableLocal = isNonRenamableLocal(F);
   bool NotEligibleForImport =
-      NonRenamableLocal || HasInlineAsmMaybeReferencingInternal ||
-      // Inliner doesn't handle variadic functions.
-      // FIXME: refactor this to use the same code that inliner is using.
-      F.isVarArg() ||
-      // Don't try to import functions with noinline attribute.
-      F.getAttributes().hasFnAttribute(Attribute::NoInline);
+      NonRenamableLocal || HasInlineAsmMaybeReferencingInternal;
   GlobalValueSummary::GVFlags Flags(F.getLinkage(), NotEligibleForImport,
                                     /* Live = */ false, F.isDSOLocal());
   FunctionSummary::FFlags FunFlags{
       F.hasFnAttribute(Attribute::ReadNone),
       F.hasFnAttribute(Attribute::ReadOnly),
-      F.hasFnAttribute(Attribute::NoRecurse),
-      F.returnDoesNotAlias(),
-  };
+      F.hasFnAttribute(Attribute::NoRecurse), F.returnDoesNotAlias(),
+      // Inliner doesn't handle variadic functions.
+      // FIXME: refactor this to use the same code that inliner is using.
+      F.isVarArg() ||
+          // Don't try to import functions with noinline attribute.
+          F.getAttributes().hasFnAttribute(Attribute::NoInline)};
   auto FuncSummary = llvm::make_unique<FunctionSummary>(
       Flags, NumInsts, FunFlags, RefEdges.takeVector(),
       CallGraphEdges.takeVector(), TypeTests.takeVector(),
@@ -478,7 +476,8 @@ ModuleSummaryIndex llvm::buildModuleSummaryIndex(
                         F->hasFnAttribute(Attribute::ReadNone),
                         F->hasFnAttribute(Attribute::ReadOnly),
                         F->hasFnAttribute(Attribute::NoRecurse),
-                        F->returnDoesNotAlias()},
+                        F->returnDoesNotAlias(),
+                        /* NoInline = */ false},
                     ArrayRef<ValueInfo>{}, ArrayRef<FunctionSummary::EdgeTy>{},
                     ArrayRef<GlobalValue::GUID>{},
                     ArrayRef<FunctionSummary::VFuncId>{},
diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
index 53787b25d0b..af4f43986ef 100644
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -740,6 +740,7 @@ lltok::Kind LLLexer::LexIdentifier() {
   KEYWORD(readOnly);
   KEYWORD(noRecurse);
   KEYWORD(returnDoesNotAlias);
+  KEYWORD(noInline);
   KEYWORD(calls);
   KEYWORD(callee);
   KEYWORD(hotness);
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index e83b9f80592..5fe1e125d48 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -7714,6 +7714,7 @@ bool LLParser::ParseFlag(unsigned &Val) {
 ///   := 'funcFlags' ':' '(' ['readNone' ':' Flag]?
 ///        [',' 'readOnly' ':' Flag]? [',' 'noRecurse' ':' Flag]?
 ///        [',' 'returnDoesNotAlias' ':' Flag]? ')'
+///        [',' 'noInline' ':' Flag]? ')'
 bool LLParser::ParseOptionalFFlags(FunctionSummary::FFlags &FFlags) {
   assert(Lex.getKind() == lltok::kw_funcFlags);
   Lex.Lex();
@@ -7749,6 +7750,12 @@ bool LLParser::ParseOptionalFFlags(FunctionSummary::FFlags &FFlags) {
         return true;
       FFlags.ReturnDoesNotAlias = Val;
       break;
+    case lltok::kw_noInline:
+      Lex.Lex();
+      if (ParseToken(lltok::colon, "expected ':'") || ParseFlag(Val))
+        return true;
+      FFlags.NoInline = Val;
+      break;
     default:
       return Error(Lex.getLoc(), "expected function flag type");
     }
diff --git a/llvm/lib/AsmParser/LLToken.h b/llvm/lib/AsmParser/LLToken.h
index a3a9930f9e3..f8f5955a16c 100644
--- a/llvm/lib/AsmParser/LLToken.h
+++ b/llvm/lib/AsmParser/LLToken.h
@@ -369,6 +369,7 @@ enum Kind {
   kw_readOnly,
   kw_noRecurse,
   kw_returnDoesNotAlias,
+  kw_noInline,
   kw_calls,
   kw_callee,
   kw_hotness,
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index aa83955e646..56e05f8f085 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -876,6 +876,7 @@ static FunctionSummary::FFlags getDecodedFFlags(uint64_t RawFlags) {
   Flags.ReadOnly = (RawFlags >> 1) & 0x1;
   Flags.NoRecurse = (RawFlags >> 2) & 0x1;
   Flags.ReturnDoesNotAlias = (RawFlags >> 3) & 0x1;
+  Flags.NoInline = (RawFlags >> 4) & 0x1;
   return Flags;
 }
 
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index d59da255be4..f4634c9d3f4 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -971,6 +971,7 @@ static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
   RawFlags |= (Flags.ReadOnly << 1);
   RawFlags |= (Flags.NoRecurse << 2);
   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
+  RawFlags |= (Flags.NoInline << 4);
   return RawFlags;
 }
 
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index eb2311da63b..3b575739263 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -2871,6 +2871,7 @@ void AssemblyWriter::printFunctionSummary(const FunctionSummary *FS) {
     Out << ", readOnly: " << FFlags.ReadOnly;
     Out << ", noRecurse: " << FFlags.NoRecurse;
     Out << ", returnDoesNotAlias: " << FFlags.ReturnDoesNotAlias;
+    Out << ", noInline: " << FFlags.NoInline;
     Out << ")";
   }
   if (!FS->calls().empty()) {
diff --git a/llvm/lib/IR/ModuleSummaryIndex.cpp b/llvm/lib/IR/ModuleSummaryIndex.cpp
index e63407c3e75..8d85f7901b0 100644
--- a/llvm/lib/IR/ModuleSummaryIndex.cpp
+++ b/llvm/lib/IR/ModuleSummaryIndex.cpp
@@ -182,8 +182,9 @@ static std::string linkageToString(GlobalValue::LinkageTypes LT) {
 
 static std::string fflagsToString(FunctionSummary::FFlags F) {
   auto FlagValue = [](unsigned V) { return V ? '1' : '0'; };
-  char FlagRep[] = {FlagValue(F.ReadNone), FlagValue(F.ReadOnly),
-                    FlagValue(F.NoRecurse), FlagValue(F.ReturnDoesNotAlias), 0};
+  char FlagRep[] = {FlagValue(F.ReadNone),     FlagValue(F.ReadOnly),
+                    FlagValue(F.NoRecurse),    FlagValue(F.ReturnDoesNotAlias),
+                    FlagValue(F.NoInline), 0};
 
   return FlagRep;
 }
diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index 16a3d112b29..31531beea5e 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -237,11 +237,19 @@ selectCallee(const ModuleSummaryIndex &Index,
           return false;
         }
 
+        // Skip if it isn't legal to import (e.g. may reference unpromotable
+        // locals).
         if (Summary->notEligibleToImport()) {
           Reason = FunctionImporter::ImportFailureReason::NotEligible;
           return false;
         }
 
+        // Don't bother importing if we can't inline it anyway.
+        if (Summary->fflags().NoInline) {
+          Reason = FunctionImporter::ImportFailureReason::NoInline;
+          return false;
+        }
+
         return true;
       });
   if (It == CalleeSummaryList.end())
@@ -318,6 +326,8 @@ getFailureName(FunctionImporter::ImportFailureReason Reason) {
     return "LocalLinkageNotInModule";
   case FunctionImporter::ImportFailureReason::NotEligible:
     return "NotEligible";
+  case FunctionImporter::ImportFailureReason::NoInline:
+    return "NoInline";
   }
   llvm_unreachable("invalid reason");
 }