Commit 1f34e282 authored by Fangrui Song's avatar Fangrui Song
Browse files

[gcov] Ignore blocks from another file 

Constructs such as inline variables, #line, and #include can create
lexical blocks with a different filename.
GCOVProfiling and llvm-cov gcov currently don't handle such cases (see
GCOVLines::writeOut and GCOVFile::readGCNO) and would incorrectly
attribute the line number to the current file.

For now, ignore such blocks. Missing line execution counts is better
than wrong ones.
parent 182de296

compiler-rt/test/profile/Posix/gcov-file-change.cpp

0 → 100644
+40 −0
Original line number Diff line number Diff line 
// RUN: rm -rf %t && split-file %s %t && cd %t

// RUN: %clangxx --coverage main.cpp -o t

// RUN: %run ./t

// RUN: llvm-cov gcov -t t-main. | FileCheck %s



//--- main.cpp

#include "a.h"

#include <stdio.h>



// CHECK:      Runs:1

/// __cxx_global_var_init contains a block from a.h. Don't attribute its lines to main.cpp.

// CHECK-NOT:  {{^ +[0-9]+:}}



inline auto *const inl_var_main = // CHECK:      1: [[#]]:inline auto

    new A;                        // CHECK-NEXT: 1: [[#]]:

void foo(int x) {                 // CHECK-NEXT: 1: [[#]]:

  if (x) {                        // CHECK-NEXT: 1: [[#]]:

#include "a.inc"

  }

}

// CHECK-NOT:  {{^ +[0-9]+:}}



int main(int argc, char *argv[]) { // CHECK:      1: [[#]]:int main

  foo(1);                          // CHECK-NEXT: 1: [[#]]:

}                                  // CHECK-NEXT: 1: [[#]]:

// CHECK-NOT:  {{^ +[0-9]+:}}



// CHECK:      Source:a.h

// CHECK:      1: 1:struct A

// CHECK-NOT:  {{^ +[0-9]+:}}



//--- a.h

struct A { A() { } };              // CHECK:      2: [[#]]:struct A

inline auto *const inl_var_a =

    new A;

/// TODO a.inc:1 should have line execution.

// CHECK-NOT:  {{^ +[0-9]+:}}



//--- a.inc

puts("");

llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp

+3 −1
Original line number Diff line number Diff line
@@ -898,7 +898,9 @@ bool GCOVProfiler::emitProfileNotes( 


          if (Line == Loc.getLine()) continue;

          Line = Loc.getLine();

          if (SP != getDISubprogram(Loc.getScope()))

          MDNode *Scope = Loc.getScope();

          // TODO: Handle blocks from another file due to #line, #include, etc.

          if (isa<DILexicalBlockFile>(Scope) || SP != getDISubprogram(Scope))

            continue;



          GCOVLines &Lines = Block.getFile(Filename);