commit 588a35b1db1e03721af62a02ec910c7583b7118a
author Lei Zhang <thestig@chromium.org> Mon May 21 18:36:08 2018 +0000
committer Chromium commit bot <commit-bot@chromium.org> Mon May 21 18:36:08 2018 +0000
tree 6e828f88fb88d15e61e756cdfa4872109cee0db4
parent 9e17392183861a2b8b64abb4d528c79613ad3d57

Avoid indexing into std::vector inside a tight loop.

In CCodec_FaxDecoder::v_GetNextLine(), a fixed size vector often needs
to be inverted. Doing so without checking bounds on every access makes a
big difference in non-optimized builds.

BUG=chromium:843899

Change-Id: Iecc0a3da22631a289745245563dab7a7c3c458d0
Reviewed-on: https://pdfium-review.googlesource.com/32744
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

core/fxcodec/codec/fx_codec_fax.cpp

diff --git a/core/fxcodec/codec/fx_codec_fax.cpp b/core/fxcodec/codec/fx_codec_fax.cpp
index 4a70b53..0a6ba3a 100644
--- a/core/fxcodec/codec/fx_codec_fax.cpp
+++ b/core/fxcodec/codec/fx_codec_fax.cpp
@@ -544,8 +544,10 @@
       m_bitpos = bitpos1;
   }
   if (m_bBlack) {
-    for (uint32_t i = 0; i < m_Pitch; ++i)
-      m_ScanlineBuf[i] = ~m_ScanlineBuf[i];
+    ASSERT(m_Pitch == m_ScanlineBuf.size());
+    uint8_t* data = m_ScanlineBuf.data();
+    for (size_t i = 0; i < m_ScanlineBuf.size(); ++i)
+      data[i] = ~data[i];
   }
   return m_ScanlineBuf.data();
 }