commit 6c772454a3faf6bacd375cf9c4dcd4d4c19debca
author Herb Derby <herb@google.com> Fri Mar 17 09:11:02 2023 -0400
committer SkCQ <skcq-be@skia-corp.google.com.iam.gserviceaccount.com> Fri Mar 17 19:01:42 2023 +0000
tree 2a669dc1450b4a497362ff89b1e6522c9b2ab852
parent 7880a8f62967bc8cd953538ba057d614e4e76a91

Fix undefined behavior packing top and left

Shifting a negative signed integer is undefined behavior in
C++11. Convert to unsigned int before packing the word together.

Change-Id: I88251eb753da1bf8887b7f06b3356e828968103a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/657996
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Herb Derby <herb@google.com>

src/core/SkGlyph.cpp

diff --git a/src/core/SkGlyph.cpp b/src/core/SkGlyph.cpp
index 4b81077..30a7ea1 100644
--- a/src/core/SkGlyph.cpp
+++ b/src/core/SkGlyph.cpp
@@ -284,7 +284,10 @@
     buffer.writeUInt(fID.value());
     buffer.writePoint({fAdvanceX, fAdvanceY});
     buffer.writeUInt(fWidth << 16 | fHeight);
-    buffer.writeUInt(fLeft << 16 | fTop);
+    // Note: << has undefined behavior for negative values.
+    const uint32_t left = fLeft;
+    const uint32_t top = fTop;
+    buffer.writeUInt(left << 16 | top);
     buffer.writeUInt(SkTo<uint32_t>(fMaskFormat));
 }