[LLVMdev] [cfe-commits] [PATCH] [llvm+clang] memset for non-8-bit bytes

Fri Oct 19 02:24:43 PDT 2012

> Please start a thread on llvmdev about this functionality, and outline what other intrinsics will have to change to add non-8-bit byte support.

Well, memset is the only we have seen so far (our back-end is ~50% finished for an initial release). We have our own front-end as well (we are currently not using the clang front-end), and currently don't use many llvm intrinsics (only llvm.stacksave/llvm.stackrestore). The memset intrinsic is generated by opt.

> This isn't the sort of feature that we just add without understanding the full impact.

The large impact we have seen is in other parts, regarding the assumtion that a byte is 8 bits. You can see a diffstat of our current patch below. However, this patch for non 8-bit bytes is a more clean approach to core changes:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120702/146050.html

It is on my todo-list to merge that patch with our changes. Do you want that kind of changes to be pushed first?

Regards,
Patrik Hägglund

 include/llvm/CodeGen/SelectionDAG.h               |  2 +-
 include/llvm/CodeGen/ValueTypes.h                 | 43 ++++++++++++++++++++++++++++++++-----------
 include/llvm/DataLayout.h                         | 22 ++++++++++++++++------
 include/llvm/IRBuilder.h                          | 16 ++++++++++++++++
 lib/Analysis/ConstantFolding.cpp                  | 74 ++++++++++++++++++++++++++++++++++++++++----------------------------------
 lib/Analysis/ValueTracking.cpp                    | 22 +++++++++++++---------
 lib/CodeGen/AsmPrinter/AsmPrinter.cpp             | 50 ++++++++++++++++++++++++++++++++++++++------------
 lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp        |  6 ++++--
 lib/CodeGen/AsmPrinter/DIE.cpp                    | 20 ++++++++++++--------
 lib/CodeGen/AsmPrinter/DwarfDebug.cpp             |  7 ++++---
 lib/CodeGen/MachineFunction.cpp                   |  2 +-
 lib/CodeGen/SelectionDAG/DAGCombiner.cpp          | 58 +++++++++++++++++++++++++++++++++-------------------------
 lib/CodeGen/SelectionDAG/LegalizeDAG.cpp          | 63 ++++++++++++++++++++++++++++++++++-----------------------------
 lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp   |  4 ++--
 lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp | 18 +++++++++---------
 lib/CodeGen/SelectionDAG/LegalizeTypes.cpp        |  2 +-
 lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp | 12 ++++++------
 lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp  | 14 +++++++-------
 lib/CodeGen/SelectionDAG/SelectionDAG.cpp         | 89 +++++++++++++++++++++++++++++++++++++++++++----------------------------------------------
 lib/CodeGen/SelectionDAG/TargetLowering.cpp       |  6 +++---
 lib/Transforms/InstCombine/InstCombineCalls.cpp   |  6 ++++--
 lib/Transforms/Scalar/GVN.cpp                     | 48 ++++++++++++++++++++++++++++++------------------
 lib/Transforms/Scalar/SROA.cpp                    | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------------------------
 lib/Transforms/Scalar/ScalarReplAggregates.cpp    | 18 +++++++++++-------
 lib/VMCore/DataLayout.cpp                         | 65 ++++++++++++++++++++++++++++++++++++++++++++++-------------------
 lib/VMCore/IRBuilder.cpp                          | 23 ++++++++++++++++++-----
 lib/VMCore/ValueTypes.cpp                         |  2 ++
 lib/VMCore/Verifier.cpp                           |  2 ++
 test/CodeGen/PowerPC/structsinmem.ll              |  8 ++++----
 test/CodeGen/PowerPC/structsinregs.ll             | 14 +++++++-------
 test/CodeGen/X86/memcpy-2.ll                      |  4 ++--
 test/CodeGen/X86/pr11985.ll                       |  6 +++---
 test/CodeGen/X86/unaligned-load.ll                | 10 +++++++++-
 33 files changed, 506 insertions(+), 326 deletions(-)

-----Original Message-----
From: Chris Lattner [mailto:clattner at apple.com] 
Sent: den 19 oktober 2012 00:03
To: Patrik Hägglund H
Cc: llvm-commits at cs.uiuc.edu; cfe-commits at cs.uiuc.edu
Subject: Re: [cfe-commits] [PATCH] [llvm+clang] memset for non-8-bit bytes

On Oct 18, 2012, at 6:11 AM, Patrik Hägglund H <patrik.h.hagglund at ericsson.com> wrote:

> We have a back-end with 16-bit bytes, and have changed the memset
> intrinsics to be able to work on arbitrary word sizes, just as memcpy.

Hi Patrik,

This is interesting.  Please start a thread on llvmdev about this functionality, and outline what other intrinsics will have to change to add non-8-bit byte support.  This isn't the sort of feature that we just add without understanding the full impact.

Also, to actually roll this out, you'll need to add lib/VMCore/AutoUpgrade.cpp support for this change, because we need to be able to read old .bc and .ll files that use the previous form of the intrinsic.

-Chris

> 
> This patch updates the type of the second parameter of memset in
> Intrinsics.td, from llvm_i8_ty, to llvm_anyint_ty:
> 
> def int_memset  : Intrinsic<[],
> -                            [llvm_anyptr_ty, llvm_i8_ty, llvm_anyint_ty,
> +                            [llvm_anyptr_ty, llvm_anyint_ty, llvm_anyint_ty,
>                              llvm_i32_ty, llvm_i1_ty],
> 
> IRBuilder.cpp and LangRef.html is updated accordingly.
> 
> To use the intrinsic, the declaration,
> 
>  declare void @llvm.memset.p0i8.i32(i8* <dest>, i8 <val>,
>                                     i32 <len>, i32 <align>, i1 <isvolatile>)
> 
> now becomes
> 
>  declare void @llvm.memset.p0i8.i8.i32(i8* <dest>, i8 <val>,
>                                        i32 <len>, i32 <align>, i1 <isvolatile>)
> 
> The bulk of this patch consists of such changes (mainly in tests).
> 
> Some tests in clang has to be updated, as shown by the second patch file.
> 
> /Patrik Hägglund  
> <0002-clang-Change-memset-in-Intrinsics.td-to-take-anyint.patch><0001-llvm-Change-memset-in-Intrinsics.td-to-take-anyint.patch>_______________________________________________
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