-fcatch-undefined-behavior: add the -ftrapv checks to the set of things caught
by this mode, and also check for signed left shift overflow. The rules for the
latter are a little subtle:
* neither C89 nor C++98 specify the behavior of a signed left shift at all
* in C99 and C11, shifting a 1 bit into the sign bit has undefined behavior
* in C++11, with core issue 1457, shifting a 1 bit *out* of the sign bit has
undefined behavior
As of this change, we use the C99 rules for all C language variants, and the
C++11 rules for all C++ language variants. Once we have individual
-fcatch-undefined-behavior= flags, this should be revisited.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162634 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/catch-undef-behavior.c b/test/CodeGen/catch-undef-behavior.c
index 8c45fa5..5832b6c 100644
--- a/test/CodeGen/catch-undef-behavior.c
+++ b/test/CodeGen/catch-undef-behavior.c
@@ -19,3 +19,28 @@
// CHECK-NEXT: icmp eq i64 %[[MISALIGN]], 0
return *a;
}
+
+// CHECK: @lsh_overflow
+int lsh_overflow(int a, int b) {
+ // CHECK: %[[INBOUNDS:.*]] = icmp ule i32 %[[RHS:.*]], 31
+ // CHECK-NEXT: br i1 %[[INBOUNDS]]
+
+ // CHECK: %[[SHIFTED_OUT_WIDTH:.*]] = sub nuw nsw i32 31, %[[RHS]]
+ // CHECK-NEXT: %[[SHIFTED_OUT:.*]] = lshr i32 %[[LHS:.*]], %[[SHIFTED_OUT_WIDTH]]
+ // CHECK-NEXT: %[[NO_OVERFLOW:.*]] = icmp eq i32 %[[SHIFTED_OUT]], 0
+ // CHECK-NEXT: br i1 %[[NO_OVERFLOW]]
+
+ // CHECK: %[[RET:.*]] = shl i32 %[[LHS]], %[[RHS]]
+ // CHECK-NEXT: ret i32 %[[RET]]
+ return a << b;
+}
+
+// CHECK: @rsh_inbounds
+int rsh_inbounds(int a, int b) {
+ // CHECK: %[[INBOUNDS:.*]] = icmp ult i32 %[[RHS:.*]], 32
+ // CHECK: br i1 %[[INBOUNDS]]
+
+ // CHECK: %[[RET:.*]] = ashr i32 %[[LHS]], %[[RHS]]
+ // CHECK-NEXT: ret i32 %[[RET]]
+ return a >> b;
+}