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| author | Dmitry Panov <dop251@gmail.com> | 2022-12-28 23:05:26 +0000 |
|---|---|---|
| committer | Gopher Robot <gobot@golang.org> | 2023-01-24 19:10:58 +0000 |
| commit | 7f9ee2ba5b3b60a4e71650abe5d94e0ef85720d1 (patch) | |
| tree | b8ccb1d698007e6e561e0a99ed224e25278dbbf5 /src/math/all_test.go | |
| parent | 3900ba4baf0e3b309a55b5ac4dd25f709df09772 (diff) | |
| download | go-7f9ee2ba5b3b60a4e71650abe5d94e0ef85720d1.tar.xz | |
math: handle int64 overflows for odd integer exponents in Pow(-0, y)
The existing implementation does a float64 to int64 conversion in order to check whether the number is odd, however it does not check for overflows. If an overflow occurs, the result is implementation-defined and while it happens to work on amd64 and i386, it produces an incorrect result on arm64 and possibly other architectures.
This change fixes that and also avoids calling isOddInt altogether if the base is +0, because it's unnecessary.
(I was considering avoiding the extra check if runtime.GOARCH is "amd64" or "i386", but I can't see this pattern being used anywhere outside the tests. And having separate files with build tags just for isOddInt() seems like an overkill)
Fixes #57465
Change-Id: Ieb243796194412aa6b98fac05fd19766ca2413ef
GitHub-Last-Rev: 3bfbd85c4cd6c5dc3d15239e180c99764a19ca88
GitHub-Pull-Request: golang/go#57494
Reviewed-on: https://go-review.googlesource.com/c/go/+/459815
Auto-Submit: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Bypass: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Diffstat (limited to 'src/math/all_test.go')
| -rw-r--r-- | src/math/all_test.go | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/src/math/all_test.go b/src/math/all_test.go index 8d5e0ad439..886267bc17 100644 --- a/src/math/all_test.go +++ b/src/math/all_test.go @@ -1687,6 +1687,12 @@ var vfpowSC = [][2]float64{ {Nextafter(1, -2), float64(1 << 63)}, {Nextafter(-1, 2), float64(1 << 63)}, {Nextafter(-1, -2), float64(1 << 63)}, + + // Issue #57465 + {Copysign(0, -1), 1e19}, + {Copysign(0, -1), -1e19}, + {Copysign(0, -1), 1<<53 - 1}, + {Copysign(0, -1), -(1<<53 - 1)}, } var powSC = []float64{ 0, // pow(-Inf, -Pi) @@ -1762,6 +1768,12 @@ var powSC = []float64{ 0, // pow(Nextafter(1, -2), float64(1 << 63)) 0, // pow(Nextafter(-1, 2), float64(1 << 63)) Inf(1), // pow(Nextafter(-1, -2), float64(1 << 63)) + + // Issue #57465 + 0, // pow(-0, 1e19) + Inf(1), // pow(-0, -1e19) + Copysign(0, -1), // pow(-0, 1<<53 -1) + Inf(-1), // pow(-0, -(1<<53 -1)) } var vfpow10SC = []int{ |