r220543 - Add a new -fmerge-functions -cc1 flag that enables function merging.

[Nick Lewycky]

Author: nicholas
Date: Thu Oct 23 19:49:29 2014
New Revision: 220543

URL: http://llvm.org/viewvc/llvm-project?rev=220543&view=rev
Log:
Add a new -fmerge-functions -cc1 flag that enables function merging.

Added:
    cfe/trunk/test/CodeGenCXX/merge-functions.cpp
Modified:
    cfe/trunk/include/clang/Driver/CC1Options.td
    cfe/trunk/include/clang/Frontend/CodeGenOptions.def
    cfe/trunk/lib/CodeGen/BackendUtil.cpp
    cfe/trunk/lib/Frontend/CompilerInvocation.cpp

Modified: cfe/trunk/include/clang/Driver/CC1Options.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/CC1Options.td?rev=220543&r1=220542&r2=220543&view=diff
==============================================================================
--- cfe/trunk/include/clang/Driver/CC1Options.td (original)
+++ cfe/trunk/include/clang/Driver/CC1Options.td Thu Oct 23 19:49:29 2014
@@ -169,6 +169,8 @@ def no_implicit_float : Flag<["-"], "no-
   HelpText<"Don't generate implicit floating point instructions">;
 def fdump_vtable_layouts : Flag<["-"], "fdump-vtable-layouts">,
   HelpText<"Dump the layouts of all vtables that will be emitted in a translation unit">;
+def fmerge_functions : Flag<["-"], "fmerge-functions">,
+  HelpText<"Permit merging of identical functions when optimizing.">;
 def femit_coverage_notes : Flag<["-"], "femit-coverage-notes">,
   HelpText<"Emit a gcov coverage notes file when compiling.">;
 def femit_coverage_data: Flag<["-"], "femit-coverage-data">,

Modified: cfe/trunk/include/clang/Frontend/CodeGenOptions.def
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Frontend/CodeGenOptions.def?rev=220543&r1=220542&r2=220543&view=diff
==============================================================================
--- cfe/trunk/include/clang/Frontend/CodeGenOptions.def (original)
+++ cfe/trunk/include/clang/Frontend/CodeGenOptions.def Thu Oct 23 19:49:29 2014
@@ -67,6 +67,7 @@ CODEGENOPT(InstrumentForProfiling , 1, 0
 CODEGENOPT(LessPreciseFPMAD  , 1, 0) ///< Enable less precise MAD instructions to
                                      ///< be generated.
 CODEGENOPT(MergeAllConstants , 1, 1) ///< Merge identical constants.
+CODEGENOPT(MergeFunctions    , 1, 0) ///< Set when -fmerge-functions is enabled.
 CODEGENOPT(NoCommon          , 1, 0) ///< Set when -fno-common or C++ is enabled.
 CODEGENOPT(NoDwarfDirectoryAsm , 1, 0) ///< Set when -fno-dwarf-directory-asm is
                                        ///< enabled.

Modified: cfe/trunk/lib/CodeGen/BackendUtil.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/BackendUtil.cpp?rev=220543&r1=220542&r2=220543&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/BackendUtil.cpp (original)
+++ cfe/trunk/lib/CodeGen/BackendUtil.cpp Thu Oct 23 19:49:29 2014
@@ -247,6 +247,7 @@ void EmitAssemblyHelper::CreatePasses()
   PMBuilder.DisableTailCalls = CodeGenOpts.DisableTailCalls;
   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
+  PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
   PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,

Modified: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInvocation.cpp?rev=220543&r1=220542&r2=220543&view=diff
==============================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp (original)
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp Thu Oct 23 19:49:29 2014
@@ -452,6 +452,7 @@ static bool ParseCodeGenArgs(CodeGenOpti
                                        OPT_fno_function_sections, false);
   Opts.DataSections = Args.hasFlag(OPT_fdata_sections,
                                    OPT_fno_data_sections, false);
+  Opts.MergeFunctions = Args.hasArg(OPT_fmerge_functions);
 
   Opts.VectorizeBB = Args.hasArg(OPT_vectorize_slp_aggressive);
   Opts.VectorizeLoop = Args.hasArg(OPT_vectorize_loops);

Added: cfe/trunk/test/CodeGenCXX/merge-functions.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/merge-functions.cpp?rev=220543&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/merge-functions.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/merge-functions.cpp Thu Oct 23 19:49:29 2014
@@ -0,0 +1,14 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -O1 -fmerge-functions -emit-llvm -o - -x c++ < %s | FileCheck %s
+
+// Basic functionality test. Function merging doesn't kick in on functions that
+// are too simple.
+
+struct A {
+  virtual int f(int x, int *p) { return x ? *p : 1; }
+  virtual int g(int x, int *p) { return x ? *p : 1; }
+} a;
+
+// CHECK: define {{.*}} @_ZN1A1gEiPi
+// CHECK-NEXT: tail call i32 @_ZN1A1fEiPi
+// CHECK-NEXT: ret