https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68173
Bug ID: 68173
Summary: gcc does not terminate with -O0 on source file with a
very large expression
Product: gcc
Version: 5.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: fuz at fuz dot su
Target Milestone: ---
Created attachment 36632
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36632&action=edit
Testcase (file expands to a 20 MiB C source code form)
In this Stack Overflow question [1] OP has trouble compiling a 20 MiB source
file with gcc. Testing reveals that the source file compiles in roughly 1½
minutes when compiled with -O3 but the compiler doesn't terminate in 8 hours
when compiling with -O0. A reduced and self-contained variation of the source
code is attached. Due to its large size, it has been xz-compressed. Other
compilers (tested: tcc, clang) do not exhibit this problem and manage to
compile the source file within about a minute.
The source code comprises a single function with one arithmetic expression
making up 99.9% of the entire source file. Please have caution when opening
this file with an editor, some editors like nano become unresponsive when
reaching the line containing that expression.
I'm compiling on amd64 Linux for amd64 Linux with a gcc 5.1 RC1. I do not know
if this issue pertains trunk.
[1]: http://stackoverflow.com/q/33443626/417501
