[libc-commits] [libc] [libc] Moved shared constexpr to the top (PR #144569)

[via libc-commits]

https://github.com/sribee8 updated https://github.com/llvm/llvm-project/pull/144569

>From 2163dcadb85b13f7da4478deba8f0bf277480061 Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Tue, 17 Jun 2025 17:11:49 +0000
Subject: [PATCH 1/3] [libc] Moved shared constexpr to the top

Some conversions shared constexpr so moved to the top.
---
 libc/src/__support/wchar/character_converter.cpp | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/libc/src/__support/wchar/character_converter.cpp b/libc/src/__support/wchar/character_converter.cpp
index 3b9046dfb9a76..e45ee4105c285 100644
--- a/libc/src/__support/wchar/character_converter.cpp
+++ b/libc/src/__support/wchar/character_converter.cpp
@@ -19,6 +19,12 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 
+constexpr size_t ENCODED_BITS_PER_UTF8 = 6;
+// the number of bits per utf-8 byte that actually encode character
+// information not metadata (# of bits excluding the byte headers)
+constexpr uint32_t MASK_ENCODED_BITS =
+    mask_trailing_ones<uint32_t, ENCODED_BITS_PER_UTF8>();
+
 CharacterConverter::CharacterConverter(mbstate *mbstate) { state = mbstate; }
 
 void CharacterConverter::clear() {
@@ -61,10 +67,9 @@ int CharacterConverter::push(char8_t utf8_byte) {
   }
   // Any subsequent push
   // Adding 6 more bits so need to left shift
-  constexpr size_t ENCODED_BITS_PER_UTF8 = 6;
   if (num_ones == 1 && !isComplete()) {
     char32_t byte =
-        utf8_byte & mask_trailing_ones<uint32_t, ENCODED_BITS_PER_UTF8>();
+        utf8_byte & MASK_ENCODED_BITS;
     state->partial = state->partial << ENCODED_BITS_PER_UTF8;
     state->partial |= byte;
     state->bytes_processed++;
@@ -117,12 +122,6 @@ ErrorOr<char8_t> CharacterConverter::pop_utf8() {
   constexpr char8_t FIRST_BYTE_HEADERS[] = {0, 0xC0, 0xE0, 0xF0};
   constexpr char8_t CONTINUING_BYTE_HEADER = 0x80;
 
-  // the number of bits per utf-8 byte that actually encode character
-  // information not metadata (# of bits excluding the byte headers)
-  constexpr size_t ENCODED_BITS_PER_UTF8 = 6;
-  constexpr int MASK_ENCODED_BITS =
-      mask_trailing_ones<unsigned int, ENCODED_BITS_PER_UTF8>();
-
   char32_t output;
 
   // Shift to get the next 6 bits from the utf32 encoding

>From e576531e3ac33b720e933b637579346ab96f292d Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Tue, 17 Jun 2025 17:17:21 +0000
Subject: [PATCH 2/3] fixed formatting

---
 libc/src/__support/wchar/character_converter.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/libc/src/__support/wchar/character_converter.cpp b/libc/src/__support/wchar/character_converter.cpp
index e45ee4105c285..ecc0ba30633ff 100644
--- a/libc/src/__support/wchar/character_converter.cpp
+++ b/libc/src/__support/wchar/character_converter.cpp
@@ -68,8 +68,7 @@ int CharacterConverter::push(char8_t utf8_byte) {
   // Any subsequent push
   // Adding 6 more bits so need to left shift
   if (num_ones == 1 && !isComplete()) {
-    char32_t byte =
-        utf8_byte & MASK_ENCODED_BITS;
+    char32_t byte = utf8_byte & MASK_ENCODED_BITS;
     state->partial = state->partial << ENCODED_BITS_PER_UTF8;
     state->partial |= byte;
     state->bytes_processed++;

>From 6afa7711d0d87b67fde8aab6130aee3e14ec6283 Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Tue, 17 Jun 2025 17:24:23 +0000
Subject: [PATCH 3/3] added comment

---
 libc/src/__support/wchar/character_converter.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libc/src/__support/wchar/character_converter.cpp b/libc/src/__support/wchar/character_converter.cpp
index ecc0ba30633ff..5ab0447bb08b2 100644
--- a/libc/src/__support/wchar/character_converter.cpp
+++ b/libc/src/__support/wchar/character_converter.cpp
@@ -19,9 +19,10 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 
+// This is for utf-8 bytes other than the first byte
 constexpr size_t ENCODED_BITS_PER_UTF8 = 6;
-// the number of bits per utf-8 byte that actually encode character
-// information not metadata (# of bits excluding the byte headers)
+// The number of bits per utf-8 byte that actually encode character
+// Information not metadata (# of bits excluding the byte headers)
 constexpr uint32_t MASK_ENCODED_BITS =
     mask_trailing_ones<uint32_t, ENCODED_BITS_PER_UTF8>();