Title: [261174] trunk/Source/_javascript_Core
- Revision
- 261174
- Author
- ysuz...@apple.com
- Date
- 2020-05-05 09:24:01 -0700 (Tue, 05 May 2020)
Log Message
[JSC] JSBigInt::maxLengthBits and JSBigInt::maxLength are wrong
https://bugs.webkit.org/show_bug.cgi?id=211445
Reviewed by Mark Lam.
JSBigInt::maxLengthBits and JSBigInt::maxLength definitions are wrong.
1. We are defining maxLength and maxLengthBits as an unrelated value to each other. This is wrong.
maxLength should be defined as maxLengthBits / (sizeof(Digit) * bitsPerByte).
2. We use `sizeof(void*)` and assume that `sizeof(Digit) == sizeof(void*)`. This is wrong in ARM64_32 environment
where Digit size is sizeof(uint64_t) while the pointer size is sizeof(uint32_t). This causes compile errors in ARM64_32
when the code is using these values with static_assert.
* runtime/JSBigInt.h:
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (261173 => 261174)
--- trunk/Source/_javascript_Core/ChangeLog 2020-05-05 16:09:05 UTC (rev 261173)
+++ trunk/Source/_javascript_Core/ChangeLog 2020-05-05 16:24:01 UTC (rev 261174)
@@ -1,5 +1,22 @@
2020-05-05 Yusuke Suzuki <ysuz...@apple.com>
+ [JSC] JSBigInt::maxLengthBits and JSBigInt::maxLength are wrong
+ https://bugs.webkit.org/show_bug.cgi?id=211445
+
+ Reviewed by Mark Lam.
+
+ JSBigInt::maxLengthBits and JSBigInt::maxLength definitions are wrong.
+
+ 1. We are defining maxLength and maxLengthBits as an unrelated value to each other. This is wrong.
+ maxLength should be defined as maxLengthBits / (sizeof(Digit) * bitsPerByte).
+ 2. We use `sizeof(void*)` and assume that `sizeof(Digit) == sizeof(void*)`. This is wrong in ARM64_32 environment
+ where Digit size is sizeof(uint64_t) while the pointer size is sizeof(uint32_t). This causes compile errors in ARM64_32
+ when the code is using these values with static_assert.
+
+ * runtime/JSBigInt.h:
+
+2020-05-05 Yusuke Suzuki <ysuz...@apple.com>
+
Unreviewed, reverting r261156.
Break ARM64_32 build due to existing bug
Modified: trunk/Source/_javascript_Core/runtime/JSBigInt.h (261173 => 261174)
--- trunk/Source/_javascript_Core/runtime/JSBigInt.h 2020-05-05 16:09:05 UTC (rev 261173)
+++ trunk/Source/_javascript_Core/runtime/JSBigInt.h 2020-05-05 16:24:01 UTC (rev 261174)
@@ -434,8 +434,9 @@
// maxInt / digitBits. However, we use a lower limit for now, because
// raising it later is easier than lowering it.
// Support up to 1 million bits.
- static constexpr unsigned maxLength = 1024 * 1024 / (sizeof(void*) * bitsPerByte);
- static constexpr unsigned maxLengthBits = maxInt - sizeof(void*) * bitsPerByte - 1;
+ static constexpr unsigned maxLengthBits = 1024 * 1024;
+ static constexpr unsigned maxLength = maxLengthBits / digitBits;
+ static_assert(maxLengthBits % digitBits == 0);
static uint64_t calculateMaximumCharactersRequired(unsigned length, unsigned radix, Digit lastDigit, bool sign);
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