[clang] [CIR] Upstream pointer subtraction handling (PR #163306)

[Shawn K via cfe-commits]

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@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s --check-prefix=CIR
+
+typedef unsigned long size_type;
+
+size_type size(unsigned long *_start, unsigned long *_finish) {
+  // CIR-LABEL: cir.func dso_local @_Z4sizePmS_
+  // CIR: %[[D:.*]] = cir.ptr_diff {{.*}} : !cir.ptr<!u64i> -> !s64i
+  // CIR: %[[U:.*]] = cir.cast integral %[[D]] : !s64i -> !u64i
+  // CIR: cir.return {{.*}} : !u64i
+
+  return static_cast<size_type>(_finish - _start);
+}
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kimsh02 wrote:

Incubator file didn't have LLVM checks

https://github.com/llvm/llvm-project/pull/163306