andrew.zhogin created this revision.
andrew.zhogin added a reviewer: majnemer.
andrew.zhogin added subscribers: zinovy.nis, cfe-commits.
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:
[[ http://reviews.llvm.org/D11306 | llvm patch for aliases constprop ]]
http://reviews.llvm.org/D11315
Files:
test/Analysis/devirtualize-virtual-function-calls-constprop.cpp
Index: test/Analysis/devirtualize-virtual-function-calls-constprop.cpp
===================================================================
--- test/Analysis/devirtualize-virtual-function-calls-constprop.cpp
+++ test/Analysis/devirtualize-virtual-function-calls-constprop.cpp
@@ -0,0 +1,16 @@
+// 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;
+}
Index: test/Analysis/devirtualize-virtual-function-calls-constprop.cpp
===================================================================
--- test/Analysis/devirtualize-virtual-function-calls-constprop.cpp
+++ test/Analysis/devirtualize-virtual-function-calls-constprop.cpp
@@ -0,0 +1,16 @@
+// 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;
+}
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