[sanitizer-coverage] add yet another flavour of coverage instrumentation: trace-pc-guard. The intent is to eventually replace all of {bool coverage, 8bit-counters, trace-pc} with just this one. Clang part

llvm-svn: 281432
diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
index 5c9abd1..8ba8e53 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -53,6 +53,7 @@
   CoverageTraceGep = 1 << 7,
   Coverage8bitCounters = 1 << 8,
   CoverageTracePC = 1 << 9,
+  CoverageTracePCGuard = 1 << 10,
 };
 
 /// Parse a -fsanitize= or -fno-sanitize= argument's values, diagnosing any
@@ -526,7 +527,7 @@
         << "-fsanitize-coverage=8bit-counters"
         << "-fsanitize-coverage=(func|bb|edge)";
   // trace-pc w/o func/bb/edge implies edge.
-  if ((CoverageFeatures & CoverageTracePC) &&
+  if ((CoverageFeatures & (CoverageTracePC | CoverageTracePCGuard)) &&
       !(CoverageFeatures & CoverageTypes))
     CoverageFeatures |= CoverageEdge;
 
@@ -620,7 +621,8 @@
     std::make_pair(CoverageTraceDiv, "-fsanitize-coverage-trace-div"),
     std::make_pair(CoverageTraceGep, "-fsanitize-coverage-trace-gep"),
     std::make_pair(Coverage8bitCounters, "-fsanitize-coverage-8bit-counters"),
-    std::make_pair(CoverageTracePC, "-fsanitize-coverage-trace-pc")};
+    std::make_pair(CoverageTracePC, "-fsanitize-coverage-trace-pc"),
+    std::make_pair(CoverageTracePCGuard, "-fsanitize-coverage-trace-pc-guard")};
   for (auto F : CoverageFlags) {
     if (CoverageFeatures & F.first)
       CmdArgs.push_back(Args.MakeArgString(F.second));
@@ -760,6 +762,7 @@
         .Case("trace-gep", CoverageTraceGep)
         .Case("8bit-counters", Coverage8bitCounters)
         .Case("trace-pc", CoverageTracePC)
+        .Case("trace-pc-guard", CoverageTracePCGuard)
         .Default(0);
     if (F == 0)
       D.Diag(clang::diag::err_drv_unsupported_option_argument)