[llvm-dev] question: access IR class Instruction from DAG SDValue

陳韋任 via llvm-dev llvm-dev at lists.llvm.org
Sat Nov 25 18:10:09 PST 2017

>From SDNode and MachineInstr class, I see no link between them and
IR/SDNode. The other places you can check are SelectionDAGBuilder [1] and
InstrEmitter [1], which responsible for translating IR to SDNode, and
SDNode to MachineInstr respectively.

I know you can retrieve the corresponding BasicBlock for a
MachineBasicBlock, which is easy. However, since we will do lowering and
combine during IR to SDNode transformation, I think it's hard to track the
relationship. Not sure it's the same for SDNode to MachineInstr
transformation, though.

[1] http://llvm.org/doxygen/classllvm_1_1SelectionDAGBuilder.html
[2] http://llvm.org/doxygen/classllvm_1_1InstrEmitter.html

2017-11-26 8:58 GMT+08:00 Jonathan via llvm-dev <llvm-dev at lists.llvm.org>:

> The llvm backend uses class Instruction in IR handle stage, create SDVaule
> and DAG in DAG translation stage and class MachineInstr in Machine
> instruction translation stage.
> Can I access class Instruction from DAG structure or stage, or access DAG
> and Instruction from MachineInstr structure or stage?
> Jonathan
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Wei-Ren Chen (陳韋任)
Homepage: https://people.cs.nctu.edu.tw/~chenwj
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