Don't emit coverage mapping for excluded functions

[phosek]

Summary

When a function or a file is excluded using -fprofile-list= option,
don't emit coverage mapping as doing so confuses users since those
functions would always have zero count. This also reduces the binary
size considerably in cases where only a few functions or files are
being instrumented.

[vsk]

clang/test/CodeGen/profile-filter.c

27

This is somewhat difficult to interpret. Would you be open to specifying -dump-coverage-mapping (e.g. https://godbolt.org/z/5PvvEv), in a separate cc1 invocation if needed, and checking that instead?

[phosek]

clang/test/CodeGen/profile-filter.c

27

Thanks for the suggestion, this is definitely cleaner.

[vsk]

Thanks, lgtm.

clang/lib/CodeGen/CodeGenPGO.cpp

if (CGM.getTarget().getCXXABI().hasConstructorVariants()) {
     if (const auto *CCD = dyn_cast<CXXConstructorDecl>(D))
       if (GD.getCtorType() != Ctor_Base &&
           CodeGenFunction::IsConstructorDelegationValid(CCD))
         return;
   }
   if (isa<CXXDestructorDecl>(D) && GD.getDtorType() != Dtor_Base)
     return;
 
+  CGM.ClearUnusedCoverageMapping(D);
   if (Fn->hasFnAttribute(llvm::Attribute::NoProfile))
     return;
 
-  CGM.ClearUnusedCoverageMapping(D);
   setFuncName(Fn);
 
   mapRegionCounters(D);
   if (CGM.getCodeGenOpts().CoverageMapping)
     emitCounterRegionMapping(D);
   if (PGOReader) {
     SourceManager &SM = CGM.getContext().getSourceManager();
     loadRegionCounts(PGOReader, SM.isInMainFile(D->getLocation()));

clang/test/CodeGen/profile-filter.c

-// RUN: %clang_cc1 -fprofile-instrument=clang -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -emit-llvm %s -o - | FileCheck %s
 
 // RUN: echo "fun:test1" > %t-func.list
-// RUN: %clang_cc1 -fprofile-instrument=clang -fprofile-list=%t-func.list -emit-llvm %s -o - | FileCheck %s --check-prefix=FUNC
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -fprofile-list=%t-func.list -emit-llvm %s -o - | FileCheck %s --check-prefix=FUNC
 
 // RUN: echo "src:%s" | sed -e 's/\\/\\\\/g' > %t-file.list
-// RUN: %clang_cc1 -fprofile-instrument=clang -fprofile-list=%t-file.list -emit-llvm %s -o - | FileCheck %s --check-prefix=FILE
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -fprofile-list=%t-file.list -emit-llvm %s -o - | FileCheck %s --check-prefix=FILE
 
 // RUN: echo -e "[clang]\nfun:test1\n[llvm]\nfun:test2" > %t-section.list
 // RUN: %clang_cc1 -fprofile-instrument=llvm -fprofile-list=%t-section.list -emit-llvm %s -o - | FileCheck %s --check-prefix=SECTION
 
 // RUN: echo -e "fun:test*\n!fun:test1" > %t-exclude.list
-// RUN: %clang_cc1 -fprofile-instrument=clang -fprofile-list=%t-exclude.list -emit-llvm %s -o - | FileCheck %s --check-prefix=EXCLUDE
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -fprofile-list=%t-exclude.list -emit-llvm %s -o - | FileCheck %s --check-prefix=EXCLUDE
 
 // RUN: echo "!fun:test1" > %t-exclude-only.list
-// RUN: %clang_cc1 -fprofile-instrument=clang -fprofile-list=%t-exclude-only.list -emit-llvm %s -o - | FileCheck %s --check-prefix=EXCLUDE
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -fprofile-list=%t-exclude-only.list -emit-llvm %s -o - | FileCheck %s --check-prefix=EXCLUDE
 
 unsigned i;
 
+// CHECK: @__covrec_{{[0-9A-F]+}}u = linkonce_odr hidden constant <{ i64, i32, i64, i64, [{{.*}} x i8] }> <{ {{.*}} }>, section "__llvm_covfun"
+// CHECK: @__covrec_{{[0-9A-F]+}}u = linkonce_odr hidden constant <{ i64, i32, i64, i64, [{{.*}} x i8] }> <{ {{.*}} }>, section "__llvm_covfun"
+// FUNC: @__covrec_{{[0-9A-F]+}}u = linkonce_odr hidden constant <{ i64, i32, i64, i64, [{{.*}} x i8] }> <{ {{.*}} }>, section "__llvm_covfun"
+// FUNC-NOT: @__covrec_{{[0-9A-F]+}}u = linkonce_odr hidden constant <{ i64, i32, i64, i64, [{{.*}} x i8] }> <{ {{.*}} }>, section "__llvm_covfun"
+// FILE: @__covrec_{{[0-9A-F]+}}u = linkonce_odr hidden constant <{ i64, i32, i64, i64, [{{.*}} x i8] }> <{ {{.*}} }>, section "__llvm_covfun"
+// FILE: @__covrec_{{[0-9A-F]+}}u = linkonce_odr hidden constant <{ i64, i32, i64, i64, [{{.*}} x i8] }> <{ {{.*}} }>, section "__llvm_covfun"
+// EXCLUDE: @__covrec_{{[0-9A-F]+}}u = linkonce_odr hidden constant <{ i64, i32, i64, i64, [{{.*}} x i8] }> <{ {{.*}} }>, section "__llvm_covfun"
+// EXCLUDE-NOT: @__covrec_{{[0-9A-F]+}}u = linkonce_odr hidden constant <{ i64, i32, i64, i64, [{{.*}} x i8] }> <{ {{.*}} }>, section "__llvm_covfun"
+
 // CHECK-NOT: noprofile
 // CHECK: @test1
 // FUNC-NOT: noprofile
 // FUNC: @test1
 // FILE-NOT: noprofile
 // FILE: @test1
 // SECTION: noprofile
 // SECTION: @test1