llvm dev - Nov 2014 - [LLVMdev] How to get the indices in an getelementptr Value?

Hi, all

I am a LLVM user. I want to get every element in the next instruction:

%0 = load i32* getelementptr inbounds (%struct.Args* @globalArg, i64 0, i32
2), align 4, !dbg !85, !clap !86

Now I can only get value "i32* getelementptr inbounds (%struct.Args*
@globalArg, i64 0, i32 2)" through "getOperand(0)",
but I can not get "%struct.Args* @globalArg", "i64 0", and
"i32 2" in this
instruction.

I know I can get the indices of getelementptr instructions through
"getOperand()", but now in the previous example,
I want to get the indices from a getlementptr value. How should I do? Thank
you in advance.

Best Regards!

--------------------------------------------
Qiuping Yi
Institute Of Software
Chinese Academy of Sciences
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Hi Qiuping,

I guess you need to use getPointerOperand to access the pointer operand
(@globalArg in your example) and idx_begin/idx_end iterators to access indexes.
You can find a short description of these functions in documentation [1], or
look at examples of their uses in the code, e.g. in
lib/Transforms/InstCombine/*.cpp.

[1] http://llvm.org/doxygen/classllvm_1_1GetElementPtrInst.html
<http://llvm.org/doxygen/classllvm_1_1GetElementPtrInst.html>

Best regards,
Michael
> On Nov 22, 2014, at 12:32 AM, Qiuping Yi <yiqiuping at gmail.com>
wrote:
> 
> Hi, all
> 
> I am a LLVM user. I want to get every element in the next instruction:
> 
> %0 = load i32* getelementptr inbounds (%struct.Args* @globalArg, i64 0, i32
2), align 4, !dbg !85, !clap !86
> 
> Now I can only get value "i32* getelementptr inbounds (%struct.Args*
@globalArg, i64 0, i32 2)" through "getOperand(0)",
> but I can not get "%struct.Args* @globalArg", "i64 0",
and "i32 2" in this instruction.
> 
> I know I can get the indices of getelementptr instructions through
"getOperand()", but now in the previous example,
> I want to get the indices from a getlementptr value. How should I do? Thank
you in advance.
> 
> Best Regards!
> 
> --------------------------------------------
> Qiuping Yi
> Institute Of Software
> Chinese Academy of Sciences
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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Hi Michael,

Thank you very much.

But idx_begin/idx_end iterators can only be used through a getelementptr
instruction, right? However, I think value "i32* getelementptr inbounds
(%struct.Args* @globalArg, i64 0, i32 2)" itself is not a getelementptr
instruction, so? Or could you tell me how can I get a getelementptr
instruction first from this value?


--------------------------------------------
Qiuping Yi
Institute Of Software
Chinese Academy of Sciences

On Sat, Nov 22, 2014 at 4:49 PM, Michael Zolotukhin <mzolotukhin at
apple.com>
wrote:
> Hi Qiuping,
>
> I guess you need to use getPointerOperand to access the pointer operand
> (@globalArg in your example) and idx_begin/idx_end iterators to access
> indexes. You can find a short description of these functions in
> documentation [1], or look at examples of their uses in the code, e.g.
> in lib/Transforms/InstCombine/*.cpp.
>
> [1] http://llvm.org/doxygen/classllvm_1_1GetElementPtrInst.html
>
> Best regards,
> Michael
>
> On Nov 22, 2014, at 12:32 AM, Qiuping Yi <yiqiuping at gmail.com>
wrote:
>
> Hi, all
>
> I am a LLVM user. I want to get every element in the next instruction:
>
> %0 = load i32* getelementptr inbounds (%struct.Args* @globalArg, i64 0,
> i32 2), align 4, !dbg !85, !clap !86
>
> Now I can only get value "i32* getelementptr inbounds (%struct.Args*
> @globalArg, i64 0, i32 2)" through "getOperand(0)",
> but I can not get "%struct.Args* @globalArg", "i64 0",
and "i32 2" in this
> instruction.
>
> I know I can get the indices of getelementptr instructions through
> "getOperand()", but now in the previous example,
> I want to get the indices from a getlementptr value. How should I do?
> Thank you in advance.
>
>
> Best Regards!
>
> --------------------------------------------
> Qiuping Yi
> Institute Of Software
> Chinese Academy of Sciences
>  _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
>
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