[llvm-commits] [llvm] r73622 - in /llvm/trunk: lib/Target/ARM/ARMISelDAGToDAG.cpp lib/Target/ARM/ARMInstrInfo.td lib/Target/ARM/ARMInstrThumb2.td lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp test/CodeGen/ARM/thumb2-add.ll test/CodeGen/ARM/thumb2-m

[Evan Cheng]

On Jun 22, 2009, at 11:36 PM, Anton Korobeynikov wrote:

> Hi Evan
>
>>> +def : Pat<(and (or GPR:$src, imm16high:$imm1), imm16high0xffff:
>>> $imm2),
>>> +          (tMOVTi16 GPR:$src, (HI16 imm16high:$imm1))>,
>>> +         Requires<[HasThumb2]>;
>>
>> I don't get this pattern. Can you explain?
> Dag combiner replaces the original operation sequence (or (and reg,
> 0xFFFF), (shl imm, 16)) with (and (or reg, (shl imm, 16)), (or 0xFFFF,
> (shl imm16, 16))). We're catching this case here. There are movt tests
> there. Try to disable the pattern and see, what will happen.

Sorry, I am being dense. What are the relationships between imm1 and  
imm2? How come the result instruction doesn't use imm2 at all?

Evan

>
> -- 
> With best regards, Anton Korobeynikov
> Faculty of Mathematics and Mechanics, Saint Petersburg State  
> University
>
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