search for: pr11331

> where %group must be the result of a call to llvm.load.group. Any two loads > with the same %group value are known to produce the same value. We can then > choose to eliminate the latter of the loads as redundant in GVN, or in the > event of high register pressure we could choose to reload without spilling > to the stack. What mark would GVN leave on the IR for the register

I'm looking into how we can improve devirtualization in clang, and there a language in C++ feature I'd like to take advantage of which would let us perform elimination of more vptr loads. In this code: Cls *p = new Cls; p->virtual_method1(); p->method_changing_vptr(); // uses placement new to legally change the vptr p->virtual_method2(); // invalid! Cls *q = p;