[ubsan] Omit superflous overflow checks for promoted arithmetic (PR20193)
C requires the operands of arithmetic expressions to be promoted if
their types are smaller than an int. Ubsan emits overflow checks when
this sort of type promotion occurs, even if there is no way to actually
get an overflow with the promoted type.
This patch teaches clang how to omit the superflous overflow checks
(addressing PR20193).
Testing: check-clang and check-ubsan.
Differential Revision: https://reviews.llvm.org/D29369
llvm-svn: 296213
diff --git a/clang/test/CodeGen/ubsan-promoted-arith.cpp b/clang/test/CodeGen/ubsan-promoted-arith.cpp
new file mode 100644
index 0000000..19cbc0e
--- /dev/null
+++ b/clang/test/CodeGen/ubsan-promoted-arith.cpp
@@ -0,0 +1,124 @@
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-apple-darwin10 -emit-llvm -o - %s -fsanitize=signed-integer-overflow,unsigned-integer-overflow | FileCheck %s
+
+typedef unsigned char uchar;
+typedef unsigned short ushort;
+
+enum E1 : int {
+ a
+};
+
+enum E2 : char {
+ b
+};
+
+// CHECK-LABEL: define signext i8 @_Z4add1
+// CHECK-NOT: sadd.with.overflow
+char add1(char c) { return c + c; }
+
+// CHECK-LABEL: define zeroext i8 @_Z4add2
+// CHECK-NOT: uadd.with.overflow
+uchar add2(uchar uc) { return uc + uc; }
+
+// CHECK-LABEL: define i32 @_Z4add3
+// CHECK: sadd.with.overflow
+int add3(E1 e) { return e + a; }
+
+// CHECK-LABEL: define signext i8 @_Z4add4
+// CHECK-NOT: sadd.with.overflow
+char add4(E2 e) { return e + b; }
+
+// CHECK-LABEL: define signext i8 @_Z4sub1
+// CHECK-NOT: ssub.with.overflow
+char sub1(char c) { return c - c; }
+
+// CHECK-LABEL: define zeroext i8 @_Z4sub2
+// CHECK-NOT: usub.with.overflow
+uchar sub2(uchar uc) { return uc - uc; }
+
+// CHECK-LABEL: define signext i8 @_Z4sub3
+// CHECK-NOT: ssub.with.overflow
+char sub3(char c) { return -c; }
+
+// Note: -INT_MIN can overflow.
+//
+// CHECK-LABEL: define i32 @_Z4sub4
+// CHECK: ssub.with.overflow
+int sub4(int i) { return -i; }
+
+// CHECK-LABEL: define signext i8 @_Z4mul1
+// CHECK-NOT: smul.with.overflow
+char mul1(char c) { return c * c; }
+
+// CHECK-LABEL: define zeroext i8 @_Z4mul2
+// CHECK-NOT: smul.with.overflow
+uchar mul2(uchar uc) { return uc * uc; }
+
+// Note: USHRT_MAX * USHRT_MAX can overflow.
+//
+// CHECK-LABEL: define zeroext i16 @_Z4mul3
+// CHECK: smul.with.overflow
+ushort mul3(ushort us) { return us * us; }
+
+// CHECK-LABEL: define i32 @_Z4mul4
+// CHECK: smul.with.overflow
+int mul4(int i, char c) { return i * c; }
+
+// CHECK-LABEL: define i32 @_Z4mul5
+// CHECK: smul.with.overflow
+int mul5(int i, char c) { return c * i; }
+
+// CHECK-LABEL: define signext i16 @_Z4mul6
+// CHECK-NOT: smul.with.overflow
+short mul6(short s) { return s * s; }
+
+// CHECK-LABEL: define signext i8 @_Z4div1
+// CHECK-NOT: ubsan_handle_divrem_overflow
+char div1(char c) { return c / c; }
+
+// CHECK-LABEL: define zeroext i8 @_Z4div2
+// CHECK-NOT: ubsan_handle_divrem_overflow
+uchar div2(uchar uc) { return uc / uc; }
+
+// CHECK-LABEL: define signext i8 @_Z4div3
+// CHECK-NOT: ubsan_handle_divrem_overflow
+char div3(char c, int i) { return c / i; }
+
+// CHECK-LABEL: define signext i8 @_Z4div4
+// CHECK: ubsan_handle_divrem_overflow
+char div4(int i, char c) { return i / c; }
+
+// Note: INT_MIN / -1 can overflow.
+//
+// CHECK-LABEL: define signext i8 @_Z4div5
+// CHECK: ubsan_handle_divrem_overflow
+char div5(int i, char c) { return i / c; }
+
+// CHECK-LABEL: define signext i8 @_Z4rem1
+// CHECK-NOT: ubsan_handle_divrem_overflow
+char rem1(char c) { return c % c; }
+
+// CHECK-LABEL: define zeroext i8 @_Z4rem2
+// CHECK-NOT: ubsan_handle_divrem_overflow
+uchar rem2(uchar uc) { return uc % uc; }
+
+// FIXME: This is a long-standing false negative.
+//
+// CHECK-LABEL: define signext i8 @_Z4rem3
+// rdar30301609: ubsan_handle_divrem_overflow
+char rem3(int i, char c) { return i % c; }
+
+// CHECK-LABEL: define signext i8 @_Z4inc1
+// CHECK-NOT: sadd.with.overflow
+char inc1(char c) { return c++ + (char)0; }
+
+// CHECK-LABEL: define zeroext i8 @_Z4inc2
+// CHECK-NOT: uadd.with.overflow
+uchar inc2(uchar uc) { return uc++ + (uchar)0; }
+
+// CHECK-LABEL: define void @_Z4inc3
+// CHECK-NOT: sadd.with.overflow
+void inc3(char c) { c++; }
+
+// CHECK-LABEL: define void @_Z4inc4
+// CHECK-NOT: uadd.with.overflow
+void inc4(uchar uc) { uc++; }