[LLVMbugs] [Bug 3549] New: extremelly slow -O2 compilation

bugzilla-daemon at cs.uiuc.edu bugzilla-daemon at cs.uiuc.edu
Wed Feb 11 07:20:19 PST 2009


           Summary: extremelly slow -O2 compilation
           Product: clang
           Version: unspecified
          Platform: PC
        OS/Version: FreeBSD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: LLVM Codegen
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: rdivacky at freebsd.org
                CC: llvmbugs at cs.uiuc.edu

when compiling the attached test case I am getting these times:

lev /tmp$ time ccc -c parse.c
1.933u 0.081s 0:02.04 98.5%     22993+3509k 0+19io 0pf+0w

lev /tmp$ time ccc -c -g parse.c
2.647u 0.122s 0:02.85 96.8%     22070+3357k 0+30io 0pf+0w

ie. 2-3 seconds for plain build but

lev /tmp$ time ccc -c -O2 parse.c
467.364u 0.611s 8:07.90 95.9%   23927+3528k 0+20io 0pf+0w

thats over 8 minutes!

I dont know if the problem is in clang or llvm but top shows clang binary
running. this is with r64302, during the compilation the clang process took

this is on amd64/freebsd

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