https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91409
Bug ID: 91409
Summary: Missed optimization on `labels as values` expression
Product: gcc
Version: 9.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: mserdarsanli at gmail dot com
Target Milestone: ---
I recently posted about this on SO, but it did not gain much traction:
https://stackoverflow.com/questions/55987401/gcc-clang-labels-as-values-computing-offsets-at-runtime
The missed optimization is when using `labels as values` feature and computing
address difference. The expression `&&label2 - &&label1` generates code that
does the subtraction on runtime, while it might be possible to compute it on
compile time.
Godbolt link: https://godbolt.org/z/zZdFYo
