This adds support for analyzing the instruction with the !annotation
"auto-init" in order to generate a more user-friendly remark.
For now, support the store size, and whether it's atomic/volatile.
Example:
```
auto-init.c:4:7: remark: Store inserted by -ftrivial-auto-var-init.Store size: 4 bytes. [-Rpass-missed=annotation-remarks]
int var;
^
```
Differential Revision: https://reviews.llvm.org/D97412
Using the !annotation metadata, emit remarks pointing to code added by
`-ftrivial-auto-var-init` that survived the optimizer.
Example:
```
auto-init.c:4:7: remark: Initialization inserted by -ftrivial-auto-var-init. [-Rpass-missed=annotation-remarks]
int buf[1024];
^
```
The tests are testing various situations like calls/stores/other
instructions, with debug locations, and extra debug information on
purpose: more patches will come to improve the reporting to make it more
user-friendly, and these tests will show how the reporting evolves.
Differential Revision: https://reviews.llvm.org/D97405
This patch adds a new !annotation metadata kind which can be used to
attach annotation strings to instructions.
It also adds a new pass that emits summary remarks per function with the
counts for each annotation kind.
The intended uses cases for this new metadata is annotating
'interesting' instructions and the remarks should provide additional
insight into transformations applied to a program.
To motivate this, consider these specific questions we would like to get answered:
* How many stores added for automatic variable initialization remain after optimizations? Where are they?
* How many runtime checks inserted by a frontend could be eliminated? Where are the ones that did not get eliminated?
Discussed on llvm-dev as part of 'RFC: Combining Annotation Metadata and Remarks'
(http://lists.llvm.org/pipermail/llvm-dev/2020-November/146393.html)
Reviewed By: thegameg, jdoerfert
Differential Revision: https://reviews.llvm.org/D91188
Francis Visoiu Mistrih