[llvm-bugs] [Bug 140876] `Expr::getExprLoc()` is slow

[LLVM Bugs via llvm-bugs]

Issue	140876
Summary	`Expr::getExprLoc()` is slow
Labels	slow-compile
Assignees
Reporter	tbaederr

    This first came up when the implementation of `CallExpr::getBeginLoc()` was changed and we saw a surprising drop in compile times.

We call `Expr::getExprLoc()` (and various other functions returning a `SourceLocation`) _all the time_. The assumption is that the call  is cheap and that it's fine to do even if the source location isn't used in the end.

Changing the implementation of `Expr::getExprLoc()` to just `return SourceLocation()` improves compile times considerably: https://llvm-compile-time-tracker.com/compare.php?from=a71f56d63f569ca0ed543d3d01c684ca6ac7dffd&to=2510892ea46a84a284e0cde9f2a4edae3cdb183d&stat=instructions:u

tl;dr: Up to 15%.

Quick experiment with `callgrind` when compiling `SemaExpr.cpp`:

![Image](https://github.com/user-attachments/assets/60971fbf-0056-4945-ac8f-72324c408fc1)


We should improve this.

_______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs