[LLVMbugs] [Bug 18161] New: clang is unbearably slow to compile large function with computed goto

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=18161

            Bug ID: 18161
           Summary: clang is unbearably slow to compile large function
                    with computed goto
           Product: new-bugs
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: notasas at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Created attachment 11681
  --> http://llvm.org/bugs/attachment.cgi?id=11681&action=edit
self-contained reproducer

Compiling attached file with various compilers:

$ time clang+llvm-3.3-amd64/bin/clang fametest.c -c -o fametest.o -O
real    187m31.733s
user    186m46.396s
sys    0m6.212s

$ time clang+llvm-3.3-amd64/bin/clang fametest.c -c -o fametest.o -O2
real    189m4.333s
user    188m23.232s
sys    0m2.972s

$ time clang+llvm-3.3-amd64/bin/clang fametest.c -c -o fametest.o -O0
real    0m0.856s
user    0m0.772s
sys    0m0.056s

trunk 196510:

$ Debug+Asserts/bin/clang fametest.c -c -o fametest2.o -O
<did not finish in 24h>

time ./Release/bin/clang fametest.c -c -o fametest_clangtrunk_rel.o -O
real    428m39.409s
user    427m2.568s
sys    0m11.472s

$ gcc -v
Target: x86_64-linux-gnu
gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)

$ time gcc fametest.c -c -o fametest.o -O2
real    0m30.367s
user    0m29.208s
sys    0m0.936s

$ arm-open2x-linux-gcc -v
Target: arm-open2x-linux
gcc version 4.1.1

$ time arm-open2x-linux-gcc fametest.c -c -o fametest.o -O2
real    0m25.722s
user    0m22.552s
sys    0m2.760s

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