[OpenCL] Fix assertion due to blocks

[yaxunl]

Summary

A recent change caused assertion in CodeGenFunction::EmitBlockCallExpr when a block is called.

There is code

if (!isa<ParmVarDecl>(E->getCalleeDecl()))
  Func = CGM.getOpenCLRuntime().getInvokeFunction(E->getCallee());

getCalleeDecl calls Expr::getReferencedDeclOfCallee, which does not handle
BlockExpr and returns nullptr, which causes isa to assert.

This patch fixes that.

[Anastasia]

LGTM! Thanks!

lib/AST/Expr.cpp

Decl *Expr::getReferencedDeclOfCallee() {
   } else if (UnaryOperator *UO = dyn_cast<UnaryOperator>(CEE)) {
     if (UO->getOpcode() == UO_Deref)
       CEE = UO->getSubExpr()->IgnoreParenCasts();
   }
   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CEE))
     return DRE->getDecl();
   if (MemberExpr *ME = dyn_cast<MemberExpr>(CEE))
     return ME->getMemberDecl();
+  if (auto *BE = dyn_cast<BlockExpr>(CEE))
+    return BE->getBlockDecl();
 
   return nullptr;
 }
 
 /// getBuiltinCallee - If this is a call to a builtin, return the builtin ID. If
 /// not, return 0.
 unsigned CallExpr::getBuiltinCallee() const {
   // All simple function calls (e.g. func()) are implicitly cast to pointer to

test/CodeGenOpenCL/blocks.cl

 
 // COMMON-LABEL: define {{.*}} @get42
 // COMMON: define {{.*}} @__get42_block_invoke
 // COMMON: ret i32 42
 int get42() {
   return blockArgFunc(^{return 42;});
 }
 
+// COMMON-LABEL: define {{.*}}@call_block
+// call {{.*}}@__call_block_block_invoke
+int call_block() {
+  return ^int(int num) { return num; } (11);
+}
+
 // CHECK-DEBUG: !DIDerivedType(tag: DW_TAG_member, name: "__size"
 // CHECK-DEBUG: !DIDerivedType(tag: DW_TAG_member, name: "__align"
 
 // CHECK-DEBUG-NOT: !DIDerivedType(tag: DW_TAG_member, name: "__isa"
 // CHECK-DEBUG-NOT: !DIDerivedType(tag: DW_TAG_member, name: "__flags"
 // CHECK-DEBUG-NOT: !DIDerivedType(tag: DW_TAG_member, name: "__reserved"
 // CHECK-DEBUG-NOT: !DIDerivedType(tag: DW_TAG_member, name: "__FuncPtr"