Regression test for simple devirtualization (microsoft abi)

[andrew.zhogin]

Summary

Clang generates aliases for vtable access getelementptr (microsoft ABI only). It breaks devirtualization due to constprop failing on GlobalAlias. Here is simple test aka "return ptr->f() + ptr->f_const()".

Linked with:
llvm patch for aliases constprop

[andrew.zhogin]

Added "// REQUIRES: x86-registered-target"

[majnemer]

The "test/Analysis" directory is used for tests targeting the static analyzer. That being said, I don't think we should have this test in clang. In general, it is not considered desirable to have a test in clang which exercises the optimizer. I think the test case included in D11306 is sufficient.

[andrew.zhogin]

Cancelled as unnecessary.

test/Analysis/devirtualize-virtual-function-calls-constprop.cpp

+// REQUIRES: x86-registered-target
+// RUN: %clang_cc1 -O3 %s -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -O3 %s -triple x86_64-win32 -emit-llvm -o - | FileCheck %s
+ 
+struct A {
+  virtual int f() { return 7; }
+  virtual int f_const() const { return 3; }
+};
+
+// CHECK: ret i32 10
+int f() {
+  A *ptr = new A();
+   
+  int rv = ptr->f() + ptr->f_const();
+  delete ptr;
+  return rv;
+}