blob: 7fb33cd68b4a383c0e792f6d04fb2861a7c5a06b (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
|
# `instrument-xray`
The tracking issue for this feature is: [#102921](https://github.com/rust-lang/rust/issues/102921).
------------------------
Enable generation of NOP sleds for XRay function tracing instrumentation.
For more information on XRay,
read [LLVM documentation](https://llvm.org/docs/XRay.html),
and/or the [XRay whitepaper](http://research.google.com/pubs/pub45287.html).
Set the `-Z instrument-xray` compiler flag in order to enable XRay instrumentation.
- `-Z instrument-xray` – use the default settings
- `-Z instrument-xray=skip-exit` – configure a custom setting
- `-Z instrument-xray=ignore-loops,instruction-threshold=300` –
multiple settings separated by commas
Supported options:
- `always` – force instrumentation of all functions
- `never` – do no instrument any functions
- `ignore-loops` – ignore presence of loops,
instrument functions based only on instruction count
- `instruction-threshold=10` – set a different instruction threshold for instrumentation
- `skip-entry` – do no instrument function entry
- `skip-exit` – do no instrument function exit
The default settings are:
- instrument both entry & exit from functions
- instrument functions with at least 200 instructions,
or containing a non-trivial loop
Note that `-Z instrument-xray` only enables generation of NOP sleds
which on their own don't do anything useful.
In order to actually trace the functions,
you will need to link a separate runtime library of your choice,
such as Clang's [XRay Runtime Library](https://www.llvm.org/docs/XRay.html#xray-runtime-library).
|
