[libcxx-commits] [libcxx] [libc++] Inline `text_encoding` alias offset table std::count to 884 (PR #207471)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: William Tran-Viet (smallp-o-p)

<details>
<summary>Changes</summary>

- Add count test to verify the exact number of aliases our table contains
- Should reduce compile time cost of gathering that count


---
Full diff: https://github.com/llvm/llvm-project/pull/207471.diff


8 Files Affected:

- (modified) libcxx/include/text_encoding (+2-2) 
- (added) libcxx/test/libcxx/text/text_encoding/aliases_count.pass.cpp (+41) 
- (modified) libcxx/test/std/text/text_encoding/text_encoding.ctor/id.pass.cpp (+1-1) 
- (modified) libcxx/test/std/text/text_encoding/text_encoding.ctor/string_view.pass.cpp (+1-1) 
- (modified) libcxx/test/std/text/text_encoding/text_encoding.eq/equal.id.pass.cpp (+1-1) 
- (modified) libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/empty.pass.cpp (+1-1) 
- (modified) libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/operator-bool.pass.cpp (+1-1) 
- (renamed) libcxx/test/support/test_text_encoding.h (+1) 


``````````diff
diff --git a/libcxx/include/text_encoding b/libcxx/include/text_encoding
index da39be92c3dfa..d6063482be74d 100644
--- a/libcxx/include/text_encoding
+++ b/libcxx/include/text_encoding
@@ -792,8 +792,8 @@ private:
       "11\0CP50220\0csCP50220\0";
 
   struct __offset_table {
-    constexpr static unsigned long long __num_aliases =
-        std::count(__aliases_string, __aliases_string + sizeof(__aliases_string), '\0') + 1;
+    constexpr static unsigned long long __num_aliases = 884;
+    // +2 for id::unknown, id::other sentinels
     unsigned short __table[__num_aliases];
   };
 
diff --git a/libcxx/test/libcxx/text/text_encoding/aliases_count.pass.cpp b/libcxx/test/libcxx/text/text_encoding/aliases_count.pass.cpp
new file mode 100644
index 0000000000000..365c9fe3b9ea3
--- /dev/null
+++ b/libcxx/test/libcxx/text/text_encoding/aliases_count.pass.cpp
@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <text_encoding>
+
+// REQUIRES: std-at-least-c++26
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=40000000
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-ops-limit): -fconstexpr-ops-limit=1000000000
+
+// Our table has 882 aliases exactly, test to make sure that number matches with the total alias count
+// Internally, there are 884 entries with 2 reserved for id::unknown and id::other
+#include <cassert>
+#include <ranges>
+#include <text_encoding>
+
+#include "test_text_encoding.h"
+
+constexpr bool test() {
+  long long sum = 0;
+  for (auto& enc : unique_encoding_data) {
+    std::text_encoding te{std::text_encoding::id(enc.mib)};
+
+    sum += std::ranges::size(te.aliases());
+  }
+
+  assert(sum == 882);
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/text/text_encoding/text_encoding.ctor/id.pass.cpp b/libcxx/test/std/text/text_encoding/text_encoding.ctor/id.pass.cpp
index bc3d729e770e3..12c85e6994252 100644
--- a/libcxx/test/std/text/text_encoding/text_encoding.ctor/id.pass.cpp
+++ b/libcxx/test/std/text/text_encoding/text_encoding.ctor/id.pass.cpp
@@ -19,7 +19,7 @@
 #include <text_encoding>
 #include <type_traits>
 
-#include "../test_text_encoding.h"
+#include "test_text_encoding.h"
 
 using id = std::text_encoding::id;
 
diff --git a/libcxx/test/std/text/text_encoding/text_encoding.ctor/string_view.pass.cpp b/libcxx/test/std/text/text_encoding/text_encoding.ctor/string_view.pass.cpp
index c3202f78642f2..032a4d3c08557 100644
--- a/libcxx/test/std/text/text_encoding/text_encoding.ctor/string_view.pass.cpp
+++ b/libcxx/test/std/text/text_encoding/text_encoding.ctor/string_view.pass.cpp
@@ -19,7 +19,7 @@
 #include <text_encoding>
 #include <type_traits>
 
-#include "../test_text_encoding.h"
+#include "test_text_encoding.h"
 
 using id = std::text_encoding::id;
 
diff --git a/libcxx/test/std/text/text_encoding/text_encoding.eq/equal.id.pass.cpp b/libcxx/test/std/text/text_encoding/text_encoding.eq/equal.id.pass.cpp
index 79de614299fa0..c50f539d1527a 100644
--- a/libcxx/test/std/text/text_encoding/text_encoding.eq/equal.id.pass.cpp
+++ b/libcxx/test/std/text/text_encoding/text_encoding.eq/equal.id.pass.cpp
@@ -16,7 +16,7 @@
 #include <text_encoding>
 
 #include "test_macros.h"
-#include "../test_text_encoding.h"
+#include "test_text_encoding.h"
 
 using id = std::text_encoding::id;
 
diff --git a/libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/empty.pass.cpp b/libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/empty.pass.cpp
index 367f9216ef5ff..3008e2d27927f 100644
--- a/libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/empty.pass.cpp
+++ b/libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/empty.pass.cpp
@@ -16,7 +16,7 @@
 #include <ranges>
 #include <text_encoding>
 
-#include "../../test_text_encoding.h"
+#include "test_text_encoding.h"
 
 using id = std::text_encoding::id;
 
diff --git a/libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/operator-bool.pass.cpp b/libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/operator-bool.pass.cpp
index 9d63ff4cdfccd..f122ee5c88e0b 100644
--- a/libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/operator-bool.pass.cpp
+++ b/libcxx/test/std/text/text_encoding/text_encoding.members/text_encoding.aliases_view/operator-bool.pass.cpp
@@ -16,7 +16,7 @@
 #include <ranges>
 #include <text_encoding>
 
-#include "../../test_text_encoding.h"
+#include "test_text_encoding.h"
 
 using id = std::text_encoding::id;
 
diff --git a/libcxx/test/std/text/text_encoding/test_text_encoding.h b/libcxx/test/support/test_text_encoding.h
similarity index 99%
rename from libcxx/test/std/text/text_encoding/test_text_encoding.h
rename to libcxx/test/support/test_text_encoding.h
index e18bc3aaeea15..5cef8b8ab3d0a 100644
--- a/libcxx/test/std/text/text_encoding/test_text_encoding.h
+++ b/libcxx/test/support/test_text_encoding.h
@@ -295,6 +295,7 @@ constexpr inline enc_data all_encoding_data[] = {
     {3, "csASCII"},
     {3, "iso-ir-6"},
     {3, "us"},
+    {3, "ASCII"}, // extension to match libstdc++
     {4, "ISO-8859-1"},
     {4, "ISO_8859-1:1987"},
     {4, "CP819"},

``````````

</details>


https://github.com/llvm/llvm-project/pull/207471