Make clang emit linkage names in debug info for subprograms when coverage info

is enabled. Also add a new -test-coverage cc1 flag which makes testing coverage
possible and add our first clang-side coverage test.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177470 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Driver/CC1Options.td

@@ -155,6 +155,8 @@ def coverage_function_names_in_data : Flag<["-"], "coverage-function-names-in-da
   HelpText<"Emit function names in .gcda files.">;
 def coverage_version_EQ : Joined<["-"], "coverage-version=">,
   HelpText<"Four-byte version string for gcov files.">;
+def test_coverage : Flag<["-"], "test-coverage">,
+  HelpText<"Do not generate coverage files or remove coverage changes from IR">;
 def fuse_register_sized_bitfield_access: Flag<["-"], "fuse-register-sized-bitfield-access">,
   HelpText<"Use register sized accesses to bit-fields, when possible.">;
 def relaxed_aliasing : Flag<["-"], "relaxed-aliasing">,

include/clang/Frontend/CodeGenOptions.def

@@ -42,6 +42,7 @@ CODEGENOPT(DisableLLVMOpts   , 1, 0) ///< Don't run any optimizations, for use i
                                      ///< getting .bc files that correspond to the
                                      ///< internal state before optimizations are
                                      ///< done.
+CODEGENOPT(DisableGCov       , 1, 0) ///< Don't run the GCov pass, for testing.
 CODEGENOPT(DisableRedZone    , 1, 0) ///< Set when -mno-red-zone is enabled.
 CODEGENOPT(DisableTailCalls  , 1, 0) ///< Do not emit tail calls.
 CODEGENOPT(EmitDeclMetadata  , 1, 0) ///< Emit special metadata indicating what

lib/CodeGen/BackendUtil.cpp

@@ -302,7 +302,8 @@ void EmitAssemblyHelper::CreatePasses(TargetMachine *TM) {
   // Set up the per-module pass manager.
   PassManager *MPM = getPerModulePasses(TM);
 
-  if (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes) {
+  if (!CodeGenOpts.DisableGCov &&
+      (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes)) {
     // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
     // LLVM's -default-gcov-version flag is set to something invalid.
     GCOVOptions Options;

lib/CodeGen/CGDebugInfo.cpp

@@ -2224,13 +2224,18 @@ void CGDebugInfo::EmitFunctionStart(GlobalDecl GD, QualType FnType,
       }
     }
     Name = getFunctionName(FD);
-    // Use mangled name as linkage name for c/c++ functions.
+    // Use mangled name as linkage name for C/C++ functions.
     if (FD->hasPrototype()) {
       LinkageName = CGM.getMangledName(GD);
       Flags |= llvm::DIDescriptor::FlagPrototyped;
     }
+    // No need to replicate the linkage name if it isn't different from the
+    // subprogram name, no need to have it at all unless coverage is enabled or
+    // debug is set to more than just line tables.
     if (LinkageName == Name ||
-        CGM.getCodeGenOpts().getDebugInfo() <= CodeGenOptions::DebugLineTablesOnly)
+        (!CGM.getCodeGenOpts().EmitGcovArcs &&
+         !CGM.getCodeGenOpts().EmitGcovNotes &&
+         CGM.getCodeGenOpts().getDebugInfo() <= CodeGenOptions::DebugLineTablesOnly))
       LinkageName = StringRef();
 
     if (CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo) {

lib/Frontend/CompilerInvocation.cpp

@@ -380,6 +380,7 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.VerifyModule = !Args.hasArg(OPT_disable_llvm_verifier);
   Opts.SanitizeRecover = !Args.hasArg(OPT_fno_sanitize_recover);
 
+  Opts.DisableGCov = Args.hasArg(OPT_test_coverage);
   Opts.EmitGcovArcs = Args.hasArg(OPT_femit_coverage_data);
   Opts.EmitGcovNotes = Args.hasArg(OPT_femit_coverage_notes);
   if (Opts.EmitGcovArcs || Opts.EmitGcovNotes) {

test/CodeGenCXX/coverage.cpp

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 %s -emit-llvm -o - -test-coverage -femit-coverage-notes | FileCheck %s
+
+extern "C" void test_name1() {}
+void test_name2() {}
+
+// CHECK: metadata !"test_name1", metadata !"test_name1", metadata !"",{{.*}}DW_TAG_subprogram
+// CHECK: metadata !"test_name2", metadata !"test_name2", metadata !"_Z10test_name2v",{{.*}}DW_TAG_subprogram