[LLVMbugs] [Bug 10584] New: Extremely slow compilation spending time in Greedy Register Allocator

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=10584

           Summary: Extremely slow compilation spending time in Greedy
                    Register Allocator
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Register Allocator
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: joerg at NetBSD.org
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=7015)
 --> (http://llvm.org/bugs/attachment.cgi?id=7015)
Test case for slow register allocator

Attached is the test input. Compiling with "clang -O2" takes over 1h here (on a
i7) and peaks at 8GB RES. According to -ftime-report, the majority of the time
is spend in the following passes:

   ---User Time---   --System Time--   --User+System--   ---Wall Time---  ---
Name ---
  2717.0700 ( 51.0%)   3.1400 ( 36.3%)  2720.2100 ( 51.0%)  2725.2743 ( 51.0%) 
Greedy Register Allocator
  1458.3400 ( 27.4%)   3.7500 ( 43.4%)  1462.0900 ( 27.4%)  1465.1049 ( 27.4%) 
Value Propagation
  316.5900 (  5.9%)   0.4300 (  5.0%)  317.0200 (  5.9%)  317.5998 (  5.9%) 
Simple Register Coalescing

Report for the register allocator:

   ---User Time---   --System Time--   --User+System--   ---Wall Time---  ---
Name ---
  2512.5500 ( 92.5%)   2.9600 ( 94.9%)  2515.5100 ( 92.5%)  2520.2120 ( 92.5%) 
Spiller
  200.5100 (  7.4%)   0.1400 (  4.5%)  200.6500 (  7.4%)  200.9533 (  7.4%) 
Global Splitting
   1.9700 (  0.1%)   0.0200 (  0.6%)   1.9900 (  0.1%)   1.9189 (  0.1%)  Evict

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