diff mbox series

[committed] libstdc++: Fix _Hash_bytes for I16LP32 targets [PR107885]

Message ID 20221128170005.61262-1-jwakely@redhat.com
State Committed
Commit 7b79fa930917da735f02b4f6911dfbb0a91f9714
Headers
Series [committed] libstdc++: Fix _Hash_bytes for I16LP32 targets [PR107885] |

Commit Message

Jonathan Wakely Nov. 28, 2022, 5 p.m. UTC 
  Tested x86_64-linux, built on msp430-elf and h8300-elf. Pushed to trunk.

-- >8 --

For H8/300 size_t is 32 bits wide, but (unsigned char)buf[2] << 16
promotes to int which is only 16 bits wide. The shift is then undefined.
This fixes it by converting to size_t before shifting.

libstdc++-v3/ChangeLog:

	PR libstdc++/107885
	* libsupc++/hash_bytes.cc (_Hash_bytes): Convert to size_t
	instead of implicit integer promotion to 16 bits.
---
 libstdc++-v3/libsupc++/hash_bytes.cc | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/libstdc++-v3/libsupc++/hash_bytes.cc b/libstdc++-v3/libsupc++/hash_bytes.cc
index ffdd04f7602..67e2dbb1a0f 100644
--- a/libstdc++-v3/libsupc++/hash_bytes.cc
+++ b/libstdc++-v3/libsupc++/hash_bytes.cc
@@ -90,17 +90,21 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	len -= 4;
       }
 
+    size_t k;
     // Handle the last few bytes of the input array.
     switch(len)
       {
       case 3:
-	hash ^= static_cast<unsigned char>(buf[2]) << 16;
+	k = static_cast<unsigned char>(buf[2]);
+	hash ^= k << 16;
 	[[gnu::fallthrough]];
       case 2:
-	hash ^= static_cast<unsigned char>(buf[1]) << 8;
+	k = static_cast<unsigned char>(buf[1]);
+	hash ^= k << 8;
 	[[gnu::fallthrough]];
       case 1:
-	hash ^= static_cast<unsigned char>(buf[0]);
+	k = static_cast<unsigned char>(buf[0]);
+	hash ^= k;
 	hash *= m;
       };