Add -fforce-emit-vtables

Summary:
 In many cases we can't devirtualize
 because definition of vtable is not present. Most of the
 time it is caused by inline virtual function not beeing
 emitted. Forcing emitting of vtable adds a reference of these
 inline virtual functions.
 Note that GCC was always doing it.

Reviewers: rjmccall, rsmith, amharc, kuhar

Subscribers: llvm-commits, cfe-commits

Differential Revision: https://reviews.llvm.org/D47108

Co-authored-by: Krzysztof Pszeniczny <krzysztof.pszeniczny@gmail.com>
llvm-svn: 334600

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index a959cdb2347..2aa74c38e2b 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -719,6 +719,7 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.StrictEnums = Args.hasArg(OPT_fstrict_enums);
   Opts.StrictReturn = !Args.hasArg(OPT_fno_strict_return);
   Opts.StrictVTablePointers = Args.hasArg(OPT_fstrict_vtable_pointers);
+  Opts.ForceEmitVTables = Args.hasArg(OPT_fforce_emit_vtables);
   Opts.UnsafeFPMath = Args.hasArg(OPT_menable_unsafe_fp_math) ||
                       Args.hasArg(OPT_cl_unsafe_math_optimizations) ||
                       Args.hasArg(OPT_cl_fast_relaxed_math);
@@ -2735,6 +2736,9 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
       Args.getAllArgValues(OPT_fxray_never_instrument);
   Opts.XRayAttrListFiles = Args.getAllArgValues(OPT_fxray_attr_list);
 
+  // -fforce-emit-vtables
+  Opts.ForceEmitVTables = Args.hasArg(OPT_fforce_emit_vtables);
+
   // -fallow-editor-placeholders
   Opts.AllowEditorPlaceholders = Args.hasArg(OPT_fallow_editor_placeholders);