[CodeGen] Apply 'nonnull' and 'dereferenceable(N)' to 'this' pointer
arguments.
* Adds 'nonnull' and 'dereferenceable(N)' to 'this' pointer arguments
* Gates 'nonnull' on -f(no-)delete-null-pointer-checks
* Introduces this-nonnull.cpp and microsoft-abi-this-nullable.cpp tests to
explicitly test the behavior of this change
* Refactors hundreds of over-constrained clang tests to permit these
attributes, where needed
* Updates Clang12 patch notes mentioning this change
Reviewed-by: rsmith, jdoerfert
Differential Revision: https://reviews.llvm.org/D17993
diff --git a/clang/test/CodeGenCXX/microsoft-abi-this-nullable.cpp b/clang/test/CodeGenCXX/microsoft-abi-this-nullable.cpp
new file mode 100644
index 0000000..d038a42
--- /dev/null
+++ b/clang/test/CodeGenCXX/microsoft-abi-this-nullable.cpp
@@ -0,0 +1,53 @@
+// RUN: %clang_cc1 -fno-rtti -emit-llvm %s -o - -mconstructor-aliases -triple=i386-pc-win32 | FileCheck %s
+// RUN: %clang_cc1 -fno-rtti -emit-llvm %s -o - -mconstructor-aliases -triple=i386-pc-win32 -fno-delete-null-pointer-checks | FileCheck %s
+
+struct Left {
+ virtual void left();
+};
+
+struct Right {
+ virtual void right();
+};
+
+struct ChildNoOverride : Left, Right {
+};
+
+struct ChildOverride : Left, Right {
+ virtual void left();
+ virtual void right();
+};
+
+extern "C" void foo(void *);
+
+void call_left_no_override(ChildNoOverride *child) {
+ // CHECK: %[[CHILD:.*]] = load %struct.ChildNoOverride
+ child->left();
+}
+
+void ChildOverride::left() {}
+
+void call_right_no_override(ChildNoOverride *child) {
+ child->right();
+ // When calling a right base's virtual method, one needs to adjust `this` at the caller site.
+ //
+ // CHECK: %[[CHILD_i8:.*]] = bitcast %struct.ChildNoOverride* %[[CHILD]] to i8*
+ // CHECK: %[[RIGHT_i8:.*]] = getelementptr inbounds i8, i8* %[[CHILD_i8]], i32 4
+ // CHECK: %[[RIGHT:.*]] = bitcast i8* %[[RIGHT_i8]] to %struct.Right*
+ //
+ // CHECK: %[[VFPTR:.*]] = bitcast %struct.Right* %[[RIGHT]] to void (%struct.Right*)***
+ // CHECK: %[[VFTABLE:.*]] = load void (%struct.Right*)**, void (%struct.Right*)*** %[[VFPTR]]
+ // CHECK: %[[VFUN:.*]] = getelementptr inbounds void (%struct.Right*)*, void (%struct.Right*)** %[[VFTABLE]], i64 0
+}
+
+void ChildOverride::right() {
+ foo(this);
+}
+
+void call_right_override(ChildOverride *child) {
+ child->right();
+ // Ensure that `nonnull` and `dereferenceable(N)` are not emitted whether or not null is valid
+ //
+ // CHECK: %[[RIGHT:.*]] = getelementptr inbounds i8, i8* %[[CHILD_i8]], i32 4
+ // CHECK: %[[VFUN_VALUE:.*]] = load void (i8*)*, void (i8*)** %[[VFUN]]
+ // CHECK: call x86_thiscallcc void %[[VFUN_VALUE]](i8* %[[RIGHT]])
+}
