1 files changed, 47 insertions, 0 deletions
diff --git a/test/CodeGen/nullptr-arithmetic.c b/test/CodeGen/nullptr-arithmetic.c
new file mode 100644
index 0000000000000..ce9c9765b0f7c
--- /dev/null
+++ b/test/CodeGen/nullptr-arithmetic.c
@@ -0,0 +1,47 @@
+// RUN: %clang_cc1 -S %s -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -S %s -emit-llvm -triple i686-unknown-unknown -o - | FileCheck %s
+// RUN: %clang_cc1 -S %s -emit-llvm -triple x86_64-unknown-unknown -o - | FileCheck %s
+
+#include <stdint.h>
+
+// This test is meant to verify code that handles the 'p = nullptr + n' idiom
+// used by some versions of glibc and gcc.  This is undefined behavior but
+// it is intended there to act like a conversion from a pointer-sized integer
+// to a pointer, and we would like to tolerate that.
+
+#define NULLPTRI8 ((int8_t*)0)
+
+// This should get the inttoptr instruction.
+int8_t *test1(intptr_t n) {
+  return NULLPTRI8 + n;
+}
+// CHECK-LABEL: test1
+// CHECK: inttoptr
+// CHECK-NOT: getelementptr
+
+// This doesn't meet the idiom because the element type is larger than a byte.
+int16_t *test2(intptr_t n) {
+  return (int16_t*)0 + n;
+}
+// CHECK-LABEL: test2
+// CHECK: getelementptr
+// CHECK-NOT: inttoptr
+
+// This doesn't meet the idiom because the offset is subtracted.
+int8_t* test3(intptr_t n) {
+  return NULLPTRI8 - n;
+}
+// CHECK-LABEL: test3
+// CHECK: getelementptr
+// CHECK-NOT: inttoptr
+
+// This checks the case where the offset isn't pointer-sized.
+// The front end will implicitly cast the offset to an integer, so we need to
+// make sure that doesn't cause problems on targets where integers and pointers
+// are not the same size.
+int8_t *test4(int8_t b) {
+  return NULLPTRI8 + b;
+}
+// CHECK-LABEL: test4
+// CHECK: inttoptr
+// CHECK-NOT: getelementptr