[PATCH] CodeGen: Add IntegerDivisionPass

[Tom Stellard]

On Tue, Sep 23, 2014 at 01:57:23PM -0700, Michael Ilseman wrote:
> 
> > On Sep 23, 2014, at 12:48 PM, Tom Stellard <thomas.stellard at amd.com> wrote:
> > 
> > This pass will expand unsupported div/rem instructions based on
> > the result of the newly added TargetLowering::shouldExpandDivRemInIR().
> > ---
> > 
> > A future commit will enable this pass for the R600 backend and add tests.
> > 
> > include/llvm/CodeGen/Passes.h        |   6 ++
> > include/llvm/InitializePasses.h      |   1 +
> > include/llvm/Target/TargetLowering.h |   6 ++
> > lib/CodeGen/CMakeLists.txt           |   1 +
> > lib/CodeGen/IntegerDivisionPass.cpp  | 124 +++++++++++++++++++++++++++++++++++
> > 5 files changed, 138 insertions(+)
> > create mode 100644 lib/CodeGen/IntegerDivisionPass.cpp
> > 
> > diff --git a/include/llvm/CodeGen/Passes.h b/include/llvm/CodeGen/Passes.h
> > index 31fba89..3fedd5a 100644
> > --- a/include/llvm/CodeGen/Passes.h
> > +++ b/include/llvm/CodeGen/Passes.h
> > @@ -376,6 +376,9 @@ namespace llvm {
> >   /// load-linked/store-conditional loops.
> >   extern char &AtomicExpandID;
> > 
> > +  /// Lowers unsupported integer division.
> > +  extern char &IntegerDivisionID;
> > +
> >   /// MachineLoopInfo - This pass is a loop analysis pass.
> >   extern char &MachineLoopInfoID;
> > 
> > @@ -598,6 +601,9 @@ namespace llvm {
> > 
> >   /// createJumpInstrTables - This pass creates jump-instruction tables.
> >   ModulePass *createJumpInstrTablesPass();
> > +
> > +  /// Lower unsupported integer division
> > +  FunctionPass *createIntegerDivisionPass(const TargetMachine *TM);
> > } // End llvm namespace
> > 
> > /// This initializer registers TargetMachine constructor, so the pass being
> > diff --git a/include/llvm/InitializePasses.h b/include/llvm/InitializePasses.h
> > index 2964798..99f7ab5 100644
> > --- a/include/llvm/InitializePasses.h
> > +++ b/include/llvm/InitializePasses.h
> > @@ -146,6 +146,7 @@ void initializeInlineCostAnalysisPass(PassRegistry&);
> > void initializeInstCombinerPass(PassRegistry&);
> > void initializeInstCountPass(PassRegistry&);
> > void initializeInstNamerPass(PassRegistry&);
> > +void initializeIntegerDivisionPass(PassRegistry&);
> > void initializeInternalizePassPass(PassRegistry&);
> > void initializeIntervalPartitionPass(PassRegistry&);
> > void initializeJumpInstrTableInfoPass(PassRegistry&);
> > diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
> > index 0a72225..245df33 100644
> > --- a/include/llvm/Target/TargetLowering.h
> > +++ b/include/llvm/Target/TargetLowering.h
> > @@ -1000,6 +1000,12 @@ public:
> >     return false;
> >   }
> > 
> > +  /// Returns true if the instruction should be expanded by the IR-level
> > +  /// IntegerDivision pass.
> > +  virtual bool shouldExpandDivRemInIR(const BinaryOperator &I) const {
> > +    return false;
> > +  }
> > +
> >   //===--------------------------------------------------------------------===//
> >   // TargetLowering Configuration Methods - These methods should be invoked by
> >   // the derived class constructor to configure this object for the target.
> > diff --git a/lib/CodeGen/CMakeLists.txt b/lib/CodeGen/CMakeLists.txt
> > index 0e06ed0..d002f47 100644
> > --- a/lib/CodeGen/CMakeLists.txt
> > +++ b/lib/CodeGen/CMakeLists.txt
> > @@ -25,6 +25,7 @@ add_llvm_library(LLVMCodeGen
> >   GlobalMerge.cpp
> >   IfConversion.cpp
> >   InlineSpiller.cpp
> > +  IntegerDivisionPass.cpp
> >   InterferenceCache.cpp
> >   IntrinsicLowering.cpp
> >   JumpInstrTables.cpp
> > diff --git a/lib/CodeGen/IntegerDivisionPass.cpp b/lib/CodeGen/IntegerDivisionPass.cpp
> > new file mode 100644
> > index 0000000..b198a1f
> > --- /dev/null
> > +++ b/lib/CodeGen/IntegerDivisionPass.cpp
> > @@ -0,0 +1,124 @@
> > +//===-- IntegerDivisionPass.cpp - Expand div/mod instructions -------------===//
> > +//
> > +//                     The LLVM Compiler Infrastructure
> > +//
> > +// This file is distributed under the University of Illinois Open Source
> > +// License. See LICENSE.TXT for details.
> > +//
> > +//===----------------------------------------------------------------------===//
> > +//
> > +/// \file
> > +//===----------------------------------------------------------------------===//
> > +
> > +#include "llvm/CodeGen/Passes.h"
> > +#include "llvm/IR/IRBuilder.h"
> > +#include "llvm/IR/InstVisitor.h"
> > +#include "llvm/Target/TargetLowering.h"
> > +#include "llvm/Target/TargetMachine.h"
> > +#include "llvm/Target/TargetSubtargetInfo.h"
> > +#include "llvm/Transforms/Utils/IntegerDivision.h"
> > +using namespace llvm;
> > +
> > +#define DEBUG_TYPE "integer-division"
> > +
> > +namespace {
> > +
> > +class IntegerDivision : public FunctionPass,
> > +                        public InstVisitor<IntegerDivision, bool> {
> > +
> > +  const TargetMachine *TM;
> > +  const TargetLowering *TLI;
> > +
> > +  std::vector<BinaryOperator *> Divs;
> > +  std::vector<BinaryOperator *> Rems;
> > +
> 
> As far as I can tell from the patch, these vectors are not used. What is their intent?
> 

These are leftover from a previous version of the patch.  Here is an updated
patch with them removed.

-Tom
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