|author||Austin Clements <email@example.com>||Sun Oct 16 18:23:39 2016 -0400|
|committer||Brad Fitzpatrick <firstname.lastname@example.org>||Wed Jan 25 17:18:12 2017 +0000|
[release-branch.go1.7] runtime: fix getArgInfo for deferred reflection calls Fixes #18333 (backport) getArgInfo for reflect.makeFuncStub and reflect.methodValueCall is necessarily special. These have dynamically determined argument maps that are stored in their context (that is, their *funcval). These functions are written to store this context at 0(SP) when called, and getArgInfo retrieves it from there. This technique works if getArgInfo is passed an active call frame for one of these functions. However, getArgInfo is also used in tracebackdefers, where the "call" is not a true call with an active stack frame, but a deferred call. In this situation, getArgInfo currently crashes because tracebackdefers passes a frame with sp set to 0. However, the entire approach used by getArgInfo is flawed in this situation because the wrapper has not actually executed, and hence hasn't saved this metadata to any stack frame. In the defer case, we know the *funcval from the _defer itself, so we can fix this by teaching getArgInfo to use the *funcval context directly when its available, and otherwise get it from the active call frame. While we're here, this commit simplifies getArgInfo a bit by making it play more nicely with the type system. Rather than decoding the *reflect.methodValue that is the wrapper's context as a *uintptr, just write out a copy of the reflect.methodValue type in the runtime. Fixes #16331. Fixes #17471. Change-Id: I81db4d985179b4a81c68c490cceeccbfc675456a Reviewed-on: https://go-review.googlesource.com/31138 Run-TryBot: Austin Clements <email@example.com> TryBot-Result: Gobot Gobot <firstname.lastname@example.org> Reviewed-by: Keith Randall <email@example.com> Reviewed-on: https://go-review.googlesource.com/35638 Run-TryBot: Brad Fitzpatrick <firstname.lastname@example.org> Reviewed-by: Austin Clements <email@example.com>
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