| commit | 3a03ddf735f0e8eff3f8325a496f28b71d3dbe39 | [log] [tgz] |
|---|---|---|
| author | Keith Randall <khr@golang.org> | Sun Sep 19 21:09:57 2021 -0700 |
| committer | Dmitri Shuralyov <dmitshur@golang.org> | Wed Oct 27 21:13:34 2021 +0000 |
| tree | 4b2b41695c8f16beff379a6402913d226db1e4e7 | |
| parent | 644555d34e5154215e4599610d861ec598bfbef2 [diff] |
[release-branch.go1.17] cmd/compile: ensure constant shift amounts are in range for arm Ensure constant shift amounts are in the range [0-31]. When shift amounts are out of range, bad things happen. Shift amounts out of range occur when lowering 64-bit shifts (we take an in-range shift s in [0-63] and calculate s-32 and 32-s, both of which might be out of [0-31]). The constant shift operations themselves still work, but their shift amounts get copied unmolested to operations like ORshiftLL which use only the low 5 bits. That changes an operation like <<100 which unconditionally produces 0, to <<4, which doesn't. Fixes #48479 Change-Id: I87363ef2b4ceaf3b2e316426064626efdfbb8ee3 Reviewed-on: https://go-review.googlesource.com/c/go/+/350969 Trust: Keith Randall <khr@golang.org> Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Cherry Mui <cherryyz@google.com> (cherry picked from commit eff27e858b771bf5e0b5e7e836827c7d2941e6d4) Reviewed-on: https://go-review.googlesource.com/c/go/+/351069 Reviewed-by: Austin Clements <austin@google.com>
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