* [committed] libstdc++: Fix _Hash_bytes for I16LP32 targets [PR107885]
@ 2022-11-28 17:00 Jonathan Wakely
0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2022-11-28 17:00 UTC (permalink / raw)
To: libstdc++, gcc-patches
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 --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;
};
--
2.38.1
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