[cxx2a] P1236R1: the validity of a left shift does not depend on the

value of the LHS operand.

llvm-svn: 364265

1 files changed, 19 insertions, 0 deletions

diff --git a/clang/test/CodeGenCXX/cxx2a-left-shift.cpp b/clang/test/CodeGenCXX/cxx2a-left-shift.cpp
new file mode 100644
index 00000000000..4814cfb3238
--- /dev/null
+++ b/clang/test/CodeGenCXX/cxx2a-left-shift.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,REGULAR
+// RUN: %clang_cc1 -std=c++2a -fsanitize=shift-base,shift-exponent -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,SANITIZED
+
+// CHECK-LABEL: @_Z12lsh_overflow
+int lsh_overflow(int a, int b) {
+  // SANITIZED: %[[RHS_INBOUNDS:.*]] = icmp ule i32 %[[RHS:.*]], 31
+  // SANITIZED-NEXT: br i1 %[[RHS_INBOUNDS]], label %[[VALID:.*]], label
+
+  // SANITIZED: call void @__ubsan_handle_shift_out_of_bounds
+
+  // No check for the LHS here.
+  // SANITIZED: [[VALID]]:
+  // SANITIZED-NEXT: shl i32 %
+  // SANITIZED-NEXT: ret i32
+
+  // Just ensure there's no nsw nuw flags here.
+  // REGULAR: shl i32 %
+  return a << b;
+}