Title: [231035] trunk/Source/WTF
- Revision
- 231035
- Author
- [email protected]
- Date
- 2018-04-25 17:13:35 -0700 (Wed, 25 Apr 2018)
Log Message
Gardening: Speculative build fix for Windows 32-bit to compensate for MSVC's lack of smarts.
https://bugs.webkit.org/show_bug.cgi?id=184976
<rdar://problem/39723901>
Not reviewed.
According to https://stackoverflow.com/questions/37658794/integer-constant-overflow-warning-in-constexpr,
disabling the warning around the definition of the function will not disable it
for all clients of the function.
* wtf/PtrTag.h:
(WTF::makePtrTagHash):
Modified Paths
Diff
Modified: trunk/Source/WTF/ChangeLog (231034 => 231035)
--- trunk/Source/WTF/ChangeLog 2018-04-25 23:32:58 UTC (rev 231034)
+++ trunk/Source/WTF/ChangeLog 2018-04-26 00:13:35 UTC (rev 231035)
@@ -1,5 +1,20 @@
2018-04-25 Mark Lam <[email protected]>
+ Gardening: Speculative build fix for Windows 32-bit to compensate for MSVC's lack of smarts.
+ https://bugs.webkit.org/show_bug.cgi?id=184976
+ <rdar://problem/39723901>
+
+ Not reviewed.
+
+ According to https://stackoverflow.com/questions/37658794/integer-constant-overflow-warning-in-constexpr,
+ disabling the warning around the definition of the function will not disable it
+ for all clients of the function.
+
+ * wtf/PtrTag.h:
+ (WTF::makePtrTagHash):
+
+2018-04-25 Mark Lam <[email protected]>
+
Push the definition of PtrTag down to the WTF layer.
https://bugs.webkit.org/show_bug.cgi?id=184976
<rdar://problem/39723901>
Modified: trunk/Source/WTF/wtf/PtrTag.h (231034 => 231035)
--- trunk/Source/WTF/wtf/PtrTag.h 2018-04-25 23:32:58 UTC (rev 231034)
+++ trunk/Source/WTF/wtf/PtrTag.h 2018-04-26 00:13:35 UTC (rev 231035)
@@ -48,9 +48,16 @@
template<size_t N>
constexpr uintptr_t makePtrTagHash(const char (&str)[N])
{
+ // The only reason for the following dance with casting to result64Bit and
+ // back is because, on 32-bit, MSVC will complain about "C4307: integral
+ // constant overflow" but not allow us to disable the warning for all clients
+ // of this function.
uintptr_t result = 134775813;
- for (size_t i = 0; i < N; ++i)
- result += ((result * str[i]) ^ (result >> 16));
+ for (size_t i = 0; i < N; ++i) {
+ uint64_t result64Bit = static_cast<uint64_t>(result);
+ result64Bit += ((result64Bit * str[i]) ^ (result64Bit >> 16));
+ result = static_cast<uintptr_t>(result64Bit);
+ }
return result & 0xffff;
}
_______________________________________________
webkit-changes mailing list
[email protected]
https://lists.webkit.org/mailman/listinfo/webkit-changes
