From da3d83eaed48de7391bef625685fc0a5f2bb2b80 Mon Sep 17 00:00:00 2001
From: Charles Kerr <charles@charleskerr.com>
Date: Sat, 20 Aug 2022 10:40:18 -0500
Subject: [PATCH] refactor: make blockinfo methods constexpr (#3682)

this can be constexpr and is an outlier in CPU profiling.
---
 libtransmission/block-info.cc | 44 ------------------
 libtransmission/block-info.h  | 84 ++++++++++++++++++++++++-----------
 2 files changed, 57 insertions(+), 71 deletions(-)

diff --git a/libtransmission/block-info.cc b/libtransmission/block-info.cc
index 40e4e81c2..7682d188f 100644
--- a/libtransmission/block-info.cc
+++ b/libtransmission/block-info.cc
@@ -28,47 +28,3 @@ void tr_block_info::initSizes(uint64_t total_size_in, uint32_t piece_size_in) no
     remainder = total_size_ % BlockSize;
     final_block_size_ = remainder != 0U ? remainder : BlockSize;
 }
-
-tr_block_info::Location tr_block_info::byteLoc(uint64_t byte_idx) const noexcept
-{
-    TR_ASSERT(byte_idx <= totalSize());
-
-    if (!isInitialized())
-    {
-        return {};
-    }
-
-    auto loc = Location{};
-
-    loc.byte = byte_idx;
-
-    if (byte_idx == totalSize()) // handle 0-byte files at the end of a torrent
-    {
-        loc.block = blockCount() - 1;
-        loc.piece = pieceCount() - 1;
-    }
-    else
-    {
-        loc.block = byte_idx / BlockSize;
-        loc.piece = byte_idx / pieceSize();
-    }
-
-    loc.block_offset = static_cast<uint32_t>(loc.byte - (uint64_t{ loc.block } * BlockSize));
-    loc.piece_offset = static_cast<uint32_t>(loc.byte - (uint64_t{ loc.piece } * pieceSize()));
-
-    return loc;
-}
-
-tr_block_info::Location tr_block_info::blockLoc(tr_block_index_t block) const noexcept
-{
-    TR_ASSERT(block < blockCount());
-
-    return byteLoc(uint64_t{ block } * BlockSize);
-}
-
-tr_block_info::Location tr_block_info::pieceLoc(tr_piece_index_t piece, uint32_t offset, uint32_t length) const noexcept
-{
-    TR_ASSERT(piece < pieceCount());
-
-    return byteLoc(uint64_t{ piece } * pieceSize() + offset + length);
-}
diff --git a/libtransmission/block-info.h b/libtransmission/block-info.h
index 4bde8175b..b71274f2b 100644
--- a/libtransmission/block-info.h
+++ b/libtransmission/block-info.h
@@ -64,27 +64,6 @@ public:
         return total_size_;
     }
 
-    [[nodiscard]] tr_block_span_t blockSpanForPiece(tr_piece_index_t piece) const noexcept
-    {
-        if (!isInitialized())
-        {
-            return { 0U, 0U };
-        }
-
-        return { pieceLoc(piece).block, pieceLastLoc(piece).block + 1 };
-    }
-
-    [[nodiscard]] tr_byte_span_t byteSpanForPiece(tr_piece_index_t piece) const noexcept
-    {
-        if (!isInitialized())
-        {
-            return { 0U, 0U };
-        }
-
-        auto const offset = pieceLoc(piece).byte;
-        return { offset, offset + pieceSize(piece) };
-    }
-
     struct Location
     {
         uint64_t byte = 0;
@@ -106,23 +85,74 @@ public:
         }
     };
 
+    // Location of the torrent's nth byte
+    [[nodiscard]] constexpr auto byteLoc(uint64_t byte_idx) const noexcept
+    {
+        auto loc = Location{};
+
+        if (isInitialized())
+        {
+            loc.byte = byte_idx;
+
+            if (byte_idx == totalSize()) // handle 0-byte files at the end of a torrent
+            {
+                loc.block = blockCount() - 1;
+                loc.piece = pieceCount() - 1;
+            }
+            else
+            {
+                loc.block = byte_idx / BlockSize;
+                loc.piece = byte_idx / pieceSize();
+            }
+
+            loc.block_offset = static_cast<uint32_t>(loc.byte - (uint64_t{ loc.block } * BlockSize));
+            loc.piece_offset = static_cast<uint32_t>(loc.byte - (uint64_t{ loc.piece } * pieceSize()));
+        }
+
+        return loc;
+    }
+
     // Location of the first byte in `block`.
-    [[nodiscard]] Location blockLoc(tr_block_index_t block) const noexcept;
+    [[nodiscard]] constexpr auto blockLoc(tr_block_index_t block) const noexcept
+    {
+        return byteLoc(uint64_t{ block } * BlockSize);
+    }
 
     // Location of the first byte (+ optional offset and length) in `piece`
-    [[nodiscard]] Location pieceLoc(tr_piece_index_t piece, uint32_t offset = 0, uint32_t length = 0) const noexcept;
+    [[nodiscard]] constexpr auto pieceLoc(tr_piece_index_t piece, uint32_t offset = 0, uint32_t length = 0) const noexcept
+    {
+        return byteLoc(uint64_t{ piece } * pieceSize() + offset + length);
+    }
 
-    // Location of the torrent's nth byte
-    [[nodiscard]] Location byteLoc(uint64_t byte_idx) const noexcept;
+    [[nodiscard]] constexpr tr_block_span_t blockSpanForPiece(tr_piece_index_t piece) const noexcept
+    {
+        if (!isInitialized())
+        {
+            return { 0U, 0U };
+        }
+
+        return { pieceLoc(piece).block, pieceLastLoc(piece).block + 1 };
+    }
+
+    [[nodiscard]] constexpr tr_byte_span_t byteSpanForPiece(tr_piece_index_t piece) const noexcept
+    {
+        if (!isInitialized())
+        {
+            return { 0U, 0U };
+        }
+
+        auto const offset = pieceLoc(piece).byte;
+        return { offset, offset + pieceSize(piece) };
+    }
 
 private:
     // Location of the last byte in `piece`.
-    [[nodiscard]] Location pieceLastLoc(tr_piece_index_t piece) const
+    [[nodiscard]] constexpr Location pieceLastLoc(tr_piece_index_t piece) const
     {
         return byteLoc(static_cast<uint64_t>(piece) * pieceSize() + pieceSize(piece) - 1);
     }
 
-    [[nodiscard]] bool constexpr isInitialized() const noexcept
+    [[nodiscard]] constexpr bool isInitialized() const noexcept
     {
         return piece_size_ != 0;
     }