[CIR] Implement 'builtin-addressof' for 'getPointerWithAlignment' (llvm#185684)

The 'getPointerWithAlignment' is really only called when evaluating
arguments for builtins, so the test is a touch weird as it test through
bcopy. However, this shows up in some headers, so it is important that
we support this.

This patch just adds the implementation, which mirrors classic-codegen,
except that we don't generate TBAA.

Author: erichkeane

clang/lib/CIR/CodeGen/CIRGenExpr.cpp

@@ -236,9 +236,11 @@ Address CIRGenFunction::emitPointerWithAlignment(const Expr *expr,
     case Builtin::BIaddressof:
     case Builtin::BI__addressof:
     case Builtin::BI__builtin_addressof: {
-      cgm.errorNYI(expr->getSourceRange(),
-                   "emitPointerWithAlignment: builtin addressof");
-      return Address::invalid();
+      LValue lv = emitLValue(call->getArg(0));
+      if (baseInfo)
+        *baseInfo = lv.getBaseInfo();
+      assert(!cir::MissingFeatures::opTBAA());
+      return lv.getAddress();
     }
     }
   }

clang/test/CIR/CodeGenBuiltins/builtin-bcopy.cpp

@@ -114,3 +114,21 @@ extern "C" void bcopy(const void *__src, void *__dest, size_t __n);
 void testbcopy(const void *src, void *dest, size_t n) {
   bcopy(src, dest, n);
 }
+
+// CIR-LABEL: @testaddressof(
+// CIR: %[[SRC:.*]] = cir.alloca !cir.ptr<!s8i>, !cir.ptr<!cir.ptr<!s8i>>, ["src", init]
+// CIR: %[[DEST:.*]] = cir.alloca !cir.ptr<!s8i>, !cir.ptr<!cir.ptr<!s8i>>, ["dest", init]
+// CIR: %[[SRC_TO_VOIDPTR:.*]] = cir.cast bitcast %[[SRC]] : !cir.ptr<!cir.ptr<!s8i>> -> !cir.ptr<!void>
+// CIR: %[[DEST_TO_VOIDPTR:.*]] = cir.cast bitcast %[[DEST]] : !cir.ptr<!cir.ptr<!s8i>> -> !cir.ptr<!void>
+// CIR: cir.libc.memmove {{.*}} bytes from %[[SRC_TO_VOIDPTR]] to %[[DEST_TO_VOIDPTR]]
+// LLVM-LABEL: @testaddressof(
+// LLVM: %[[SRC:.*]] = alloca ptr
+// LLVM: %[[DEST:.*]] = alloca ptr
+// LLVM: call void @llvm.memmove.p0.p0.i64(ptr %[[DEST]], ptr %[[SRC]], i64 {{.*}}, i1 false)
+// OGCG-LABEL: @testaddressof(
+// OGCG: %[[SRC:.*]] = alloca ptr
+// OGCG: %[[DEST:.*]] = alloca ptr
+// OGCG: call void @llvm.memmove.p0.p0.i64(ptr {{.*}}%[[DEST]], ptr {{.*}}%[[SRC]], i64 {{.*}}, i1 false)
+extern "C" void testaddressof(const char *src, const char *dest, size_t n) {
+  __builtin_bcopy(__builtin_addressof(src), __builtin_addressof(dest), n);
+}