Add support for /Ob1 and -finline-hint-functions flags

Add support for /Ob1 (and equivalent -finline-hint-functions), which enable
inlining only for functions marked inline, either explicitly (via inline
keyword, for example), or implicitly (function definition in class body,
for example).

This works by enabling inlining pass, and adding noinline attribute to
every function not marked inline.

Patch by Rudy Pons <rudy.pons@ilod.org>!

Differential Revision: http://reviews.llvm.org/D20647

llvm-svn: 273440

5 files changed, 20 insertions, 7 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index fc1a456c0c7..36706696791 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -328,7 +328,8 @@ void EmitAssemblyHelper::CreatePasses(ModuleSummaryIndex *ModuleSummary) {
   switch (Inlining) {
   case CodeGenOptions::NoInlining:
     break;
-  case CodeGenOptions::NormalInlining: {
+  case CodeGenOptions::NormalInlining:
+  case CodeGenOptions::OnlyHintInlining: {
     PMBuilder.Inliner =
         createFunctionInliningPass(OptLevel, CodeGenOpts.OptimizeSize);
     break;
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 99f40e3ade6..1d46eea45fd 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -686,14 +686,20 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
 
   // Pass inline keyword to optimizer if it appears explicitly on any
   // declaration. Also, in the case of -fno-inline attach NoInline
-  // attribute to all function that are not marked AlwaysInline.
+  // attribute to all functions that are not marked AlwaysInline, or
+  // to all functions that are not marked inline or implicitly inline
+  // in the case of -finline-hint-functions.
   if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
-    if (!CGM.getCodeGenOpts().NoInline) {
+    const CodeGenOptions& CodeGenOpts = CGM.getCodeGenOpts();
+    if (!CodeGenOpts.NoInline) {
       for (auto RI : FD->redecls())
         if (RI->isInlineSpecified()) {
           Fn->addFnAttr(llvm::Attribute::InlineHint);
           break;
         }
+      if (CodeGenOpts.getInlining() == CodeGenOptions::OnlyHintInlining &&
+          !FD->isInlined() && !Fn->hasFnAttribute(llvm::Attribute::InlineHint))
+        Fn->addFnAttr(llvm::Attribute::NoInline);
     } else if (!FD->hasAttr<AlwaysInlineAttr>())
       Fn->addFnAttr(llvm::Attribute::NoInline);
     if (CGM.getLangOpts().OpenMP && FD->hasAttr<OMPDeclareSimdDeclAttr>())
diff --git a/clang/lib/Driver/MSVCToolChain.cpp b/clang/lib/Driver/MSVCToolChain.cpp
index 190df24e5a0..567c7e31d3d 100644
--- a/clang/lib/Driver/MSVCToolChain.cpp
+++ b/clang/lib/Driver/MSVCToolChain.cpp
@@ -728,7 +728,7 @@ static void TranslateOptArg(Arg *A, llvm::opt::DerivedArgList &DAL,
           DAL.AddFlagArg(A, Opts.getOption(options::OPT_fno_inline));
           break;
         case '1':
-          // TODO: Inline calls to 'inline functions' only.
+          DAL.AddFlagArg(A, Opts.getOption(options::OPT_finline_hint_functions));
           break;
         case '2':
           DAL.AddFlagArg(A, Opts.getOption(options::OPT_finline_functions));
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index c0d6c52db80..b0a3f348b3c 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -5405,6 +5405,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("-fno-inline");
 
   if (Arg* InlineArg = Args.getLastArg(options::OPT_finline_functions,
+                                       options::OPT_finline_hint_functions,
                                        options::OPT_fno_inline_functions))
     InlineArg->render(Args, CmdArgs);
 
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 0836bdcc9f4..ba6f6918aa8 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -442,10 +442,15 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   // -fno-inline-functions overrides OptimizationLevel > 1.
   Opts.NoInline = Args.hasArg(OPT_fno_inline);
   if (Arg* InlineArg = Args.getLastArg(options::OPT_finline_functions,
+                                       options::OPT_finline_hint_functions,
                                        options::OPT_fno_inline_functions)) {
-    Opts.setInlining(
-      InlineArg->getOption().matches(options::OPT_finline_functions) ?
-        CodeGenOptions::NormalInlining : CodeGenOptions::OnlyAlwaysInlining);
+    const Option& InlineOpt = InlineArg->getOption();
+    if (InlineOpt.matches(options::OPT_finline_functions))
+      Opts.setInlining(CodeGenOptions::NormalInlining);
+    else if (InlineOpt.matches(options::OPT_finline_hint_functions))
+      Opts.setInlining(CodeGenOptions::OnlyHintInlining);
+    else
+      Opts.setInlining(CodeGenOptions::OnlyAlwaysInlining);
   }
 
   if (Arg *A = Args.getLastArg(OPT_fveclib)) {