[Coverage] Avoid null deref in skipRegionMappingForDecl (fixes PR32761)

Patch by Adam Folwarczny!

Differential Revision: https://reviews.llvm.org/D32406

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@301249 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CodeGenPGO.cpp

@@ -669,6 +669,9 @@ bool CodeGenPGO::skipRegionMappingForDecl(const Decl *D) {
   if (SkipCoverageMapping)
     return true;
 
+  if (!D->getBody())
+    return true;
+
   // Don't map the functions in system headers.
   const auto &SM = CGM.getContext().getSourceManager();
   auto Loc = D->getBody()->getLocStart();

test/CoverageMapping/empty-destructor.cpp

@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple i686-windows -emit-llvm-only -fcoverage-mapping -dump-coverage-mapping -fprofile-instrument=clang %s | FileCheck %s
+
+struct A {
+  virtual ~A();
+};
+
+// CHECK: ?PR32761@@YAXXZ:
+// CHECK-NEXT: File 0, [[@LINE+1]]:16 -> [[@LINE+3]]:2 = #0
+void PR32761() {
+  A a;
+}