[llvm-bugs] [Bug 35955] New: llvm-tblgen for X86GenInstrInfo.inc.tmp takes a long time due to lots of instregex use

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=35955

            Bug ID: 35955
           Summary: llvm-tblgen for X86GenInstrInfo.inc.tmp takes a long
                    time due to lots of instregex use
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: nicolasweber at gmx.de
                CC: llvm-bugs at lists.llvm.org

In a highly-parallel build (-j250), full build time is limited by llvm-tblgen
taking 1 minute to generate X86GenInstrInfo.inc.tmp and
X86GenSubtargetInfo.inc.tmp each.


Command:

cd /Users/thakis/src/llvm-build-goma/lib/Target/X86 && time
/Users/thakis/src/llvm-build-goma/bin/llvm-tblgen -gen-instr-info -I
/Users/thakis/src/llvm-rw/lib/Target/X86 -I /Users/thakis/src/llvm-rw/include
-I /Users/thakis/src/llvm-rw/lib/Target
/Users/thakis/src/llvm-rw/lib/Target/X86/X86.td -o
/Users/thakis/src/llvm-build-goma/lib/Target/X86/X86GenInstrInfo.inc.tmp


Profile:

43.05 s  100.0% 0 s             llvm-tblgen (26142)
43.05 s  100.0% 0 s              Main Thread  0x7659e
43.05 s   99.9% 0 s               start
43.04 s   99.9% 0 s                main
43.04 s   99.9% 0 s                 llvm::TableGenMain(char*, bool
(*)(llvm::raw_ostream&, llvm::RecordKeeper&))
40.53 s   94.1% 0 s                  (anonymous
namespace)::LLVMTableGenMain(llvm::raw_ostream&, llvm::RecordKeeper&)
40.53 s   94.1% 0 s                   llvm::EmitInstrInfo(llvm::RecordKeeper&,
llvm::raw_ostream&)
38.05 s   88.3% 0 s                    llvm::CodeGenTarget::getSchedModels()
const
38.05 s   88.3% 0 s                    
llvm::CodeGenSchedModels::CodeGenSchedModels(llvm::RecordKeeper&,
llvm::CodeGenTarget const&)
37.93 s   88.1% 3.00 ms                 
llvm::CodeGenSchedModels::collectSchedClasses()
37.88 s   87.9% 12.00 ms                         
llvm::CodeGenSchedModels::createInstRWClass(llvm::Record*)
37.85 s   87.9% 38.00 ms                          
llvm::SetTheory::expand(llvm::Record*)
37.77 s   87.7% 28.67 s                     (anonymous
namespace)::InstRegexOp::apply(llvm::SetTheory&, llvm::DagInit*,
llvm::SmallSetVector<llvm::Record*, 16u>&, llvm::ArrayRef<llvm::SMLoc>)
9.02 s   20.9%  1.45 s                      
llvm::Regex::match(llvm::StringRef, llvm::SmallVectorImpl<llvm::StringRef>*)
41.00 ms    0.0%        0 s                         
llvm::Regex::Regex(llvm::StringRef, unsigned int)



Looking through http://llvm-cs.pcc.me.uk/utils/TableGen/CodeGenSchedule.cpp#60
and its callers on that stack suggests that reordering could help a lot here.

All the instregex calls are pretty new (r315175, r316492, etc); maybe you could
try to speed this up some?

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