Do not allow to ignore code generation instr. after a __attribute__((noreturn)) call in task context

Closes llvm#40

Author: mikaoP

clang/lib/CodeGen/CGCall.cpp

@@ -4409,7 +4409,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
   // If the call doesn't return, finish the basic block and clear the
   // insertion point; this allows the rest of IRGen to discard
   // unreachable code.
-  if (CI->doesNotReturn()) {
+  if (CI->doesNotReturn() && !getLangOpts().OmpSs) {
     if (UnusedReturnSizePtr)
       PopCleanupBlock();
 

clang/test/OmpSs/IR/task_noreturn_call.c

@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -verify -fompss-2 -disable-llvm-passes -ferror-limit 100 %s -S -emit-llvm -o - | FileCheck %s
+// expected-no-diagnostics
+
+__attribute__((noreturn)) void foo();
+int main() {
+    #pragma oss task
+    {
+        foo();
+    }
+}
+
+// CHECK: %0 = call token @llvm.directive.region.entry() [ "DIR.OSS"([5 x i8] c"TASK\00") ]
+// CHECK-NEXT: call void (...) @foo()
+// CHECK-NEXT: call void @llvm.directive.region.exit(token %0)
+// CHECK-NEXT: ret i32 0
+