When I compile the application "zhcon" with a recent version of gcc 4.2,
cc1plus just sits there eating CPU and RAM but doesn't actually seem to do
anything. gcc 4.1 or older versions of gcc 4.2 compile the program in a few
seconds. I tried to reduce this to a small testcase and it's included below.
Unfortunately, I cannot tell what gcc is exactly doing but based on the
testcase someone should be able to figure it out. (Please update the Summary of
this bug with a better description once you know.)
20060626: works
20060714: fails
20060721: fails
I cannot test a newer gcc snapshot right now.
cc1plus just sits there:
/usr/lib/gcc-snapshot/libexec/gcc/x86_64-linux-gnu/4.2.0/cc1plus -O2 test.cpp
int main()
Analyzing compilation unitPerforming intraprocedural optimizations
Assembling functions:
int main()
The test case is below. You need to compile with -O2 -- lower levels work.
#include <asm/types.h>
#define fb_readl(addr) (*(volatile __u32 *) (addr))
#define fb_writel(b,addr) (*(volatile __u32 *) (addr) = (b))
int main() {
__u8* dest;
__u32* dest32;
dest32 = (__u32*)dest;
for (int cnt = 10; cnt--;) {
fb_writel(fb_readl(dest32) ^ 0xffffffff, dest32++);
}
}
--
Summary: [4.2 regression] cc1plus just sits there eating CPU and
RAM for a simple program
Product: gcc
Version: 4.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tbm at cyrius dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28479
