[OPENMP] Fix for PR31643: Clang crashes when compiling code on Windows

with SEH and openmp

In some cituations (during codegen for Windows SEH constructs)
CodeGenFunction instance may have CurFn equal to nullptr. OpenMP related
code does not expect such situation during cleanup.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@292590 91177308-0d34-0410-b5e6-96231b3b80d8

Author: alexey-bataev

lib/CodeGen/CodeGenFunction.cpp

@@ -112,9 +112,8 @@ CodeGenFunction::~CodeGenFunction() {
   if (FirstBlockInfo)
     destroyBlockInfos(FirstBlockInfo);
 
-  if (getLangOpts().OpenMP) {
+  if (getLangOpts().OpenMP && CurFn)
     CGM.getOpenMPRuntime().functionFinished(*this);
-  }
 }
 
 CharUnits CodeGenFunction::getNaturalPointeeTypeAlignment(QualType T,

test/OpenMP/openmp_seh.c

@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -verify -triple x86_64-pc-windows-msvc19.0.0 -fopenmp -fms-compatibility -x c++ -emit-llvm %s -o - | FileCheck %s
+// expected-no-diagnostics
+// REQUIRES: x86-registered-target
+extern "C" {
+void __cpuid(int[4], int);
+}
+
+// CHECK-LABEL: @main
+int main(void) {
+  __try {
+    int info[4];
+    __cpuid(info, 1);
+  } __except (1) {
+  }
+
+  return 0;
+}
+