http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54337
Bug #: 54337
Summary: Dramatic Compilation slow-down on higher Optimizaitons
Classification: Unclassified
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: nbharg...@google.com
Created attachment 28061
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28061
Test Case
The attached file contains a few function definitions followed by a main method
with a single line of code duplicated 2500 times.
At optimization levels O0, the code compiles relatively quickly (~8s).
However, at optimization levels O2 and O3, the compilation time jumps to over
30s to compile -- almost a 4x difference.
Interesting things about what speeds up the optimized compilation:
Having an if-statement with an empty body cuts down compilation times on all
optimization levels to under 3s.
This could be related to http://llvm.org/bugs/show_bug.cgi?id=13651, as the
problem was discovered in a file that repeats a macro heavily, as these
examples do.
