InstrProf: Only disable coverage in built-in macros, not all system macros

The issue I was trying to solve in r236547 was about built-in macros,
but I disabled coverage in all system macros. This is actually a bit
of overkill, and makes the display of coverage around system macros
degrade unnecessarily. Instead, limit this to builtins specifically.

llvm-svn: 237397

clang/lib/CodeGen/CoverageMappingGen.cpp

@@ -134,18 +134,23 @@ public:
                            : SM.getIncludeLoc(SM.getFileID(Loc));
   }
 
-  /// \brief Get the start of \c S ignoring macro arguments and system macros.
+  /// \brief Return true if \c Loc is a location in a built-in macro.
+  bool isInBuiltin(SourceLocation Loc) {
+    return strcmp(SM.getBufferName(SM.getSpellingLoc(Loc)), "<built-in>") == 0;
+  }
+
+  /// \brief Get the start of \c S ignoring macro arguments and builtin macros.
   SourceLocation getStart(const Stmt *S) {
     SourceLocation Loc = S->getLocStart();
-    while (SM.isMacroArgExpansion(Loc) || SM.isInSystemMacro(Loc))
+    while (SM.isMacroArgExpansion(Loc) || isInBuiltin(Loc))
       Loc = SM.getImmediateExpansionRange(Loc).first;
     return Loc;
   }
 
-  /// \brief Get the end of \c S ignoring macro arguments and system macros.
+  /// \brief Get the end of \c S ignoring macro arguments and builtin macros.
   SourceLocation getEnd(const Stmt *S) {
     SourceLocation Loc = S->getLocEnd();
-    while (SM.isMacroArgExpansion(Loc) || SM.isInSystemMacro(Loc))
+    while (SM.isMacroArgExpansion(Loc) || isInBuiltin(Loc))
       Loc = SM.getImmediateExpansionRange(Loc).first;
     return getPreciseTokenLocEnd(Loc);
   }

clang/test/CoverageMapping/system_macro.c

@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -fprofile-instr-generate -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name system_macro.c -o - %s | FileCheck %s
+
+#ifdef IS_SYSHEADER
+
+#pragma clang system_header
+#define Func(x) if (x) {}
+#define SomeType int
+
+#else
+
+#define IS_SYSHEADER
+#include __FILE__
+
+// CHECK-LABEL: doSomething:
+void doSomething(int x) { // CHECK: File 0, [[@LINE]]:25 -> {{[0-9:]+}} = #0
+  Func(x); // CHECK: Expansion,File 0, [[@LINE]]:3 -> [[@LINE]]:7
+  return;
+  // CHECK: Expansion,File 0, [[@LINE+1]]:3 -> [[@LINE+1]]:11
+  SomeType *f; // CHECK: File 0, [[@LINE]]:11 -> {{[0-9:]+}} = 0
+}
+
+int main() {}
+
+#endif