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| author | Josh Bleecher Snyder <josharian@gmail.com> | 2021-09-21 13:48:23 -0700 |
|---|---|---|
| committer | Josh Bleecher Snyder <josharian@gmail.com> | 2021-09-27 20:58:24 +0000 |
| commit | 6c163e5ac9cdb258566f1287de7915a2fd30a0de (patch) | |
| tree | 88b75c49a5012c99d4f1e3885119eaed3482d16c /src/runtime/runtime2.go | |
| parent | e54843f2f4c3b11b52b691eaa187871fb4355d4c (diff) | |
| download | go-6c163e5ac9cdb258566f1287de7915a2fd30a0de.tar.xz | |
runtime: change funcinl sentinel value from 0 to ^0
_func and funcinl are type-punned.
We distinguish them at runtime by inspecting the first word.
Prior to this change, we used 0 as the sentinel value
that means that a Func is a funcinl.
That worked because _func's first word is the functions' entry PC,
and 0 is not a valid PC. I plan to make *_func's entry PC relative
to the containing module. As a result, 0 will be a valid value,
for the first function in the module.
Switch to ^0 as the new sentinel value, which is neither a valid
entry PC nor a valid PC offset.
Change-Id: I4c718523a083ed6edd57767c3548640681993522
Reviewed-on: https://go-review.googlesource.com/c/go/+/351459
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Diffstat (limited to 'src/runtime/runtime2.go')
| -rw-r--r-- | src/runtime/runtime2.go | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go index 04bd5cb887..442042eb16 100644 --- a/src/runtime/runtime2.go +++ b/src/runtime/runtime2.go @@ -879,8 +879,8 @@ type _func struct { // A *Func can be either a *_func or a *funcinl, and they are distinguished // by the first uintptr. type funcinl struct { - zero uintptr // set to 0 to distinguish from _func - entry uintptr // entry of the real (the "outermost") frame. + ones uintptr // set to ^0 to distinguish from _func + entry uintptr // entry of the real (the "outermost") frame name string file string line int |