[llvm] r284580 - [Thumb-1] Synthesize TBB/TBH instructions to make use of compressed jump tables

[James Molloy via llvm-commits]

Thanks Eli, I’ll take a look first thing tomorrow. If this is blocking you, feel free to revert.

James
> On 19 Oct 2016, at 19:30, Friedman, Eli <efriedma at codeaurora.org> wrote:
> 
> On 10/19/2016 5:06 AM, James Molloy via llvm-commits wrote:
>> Author: jamesm
>> Date: Wed Oct 19 07:06:49 2016
>> New Revision: 284580
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=284580&view=rev
>> Log:
>> [Thumb-1] Synthesize TBB/TBH instructions to make use of compressed jump tables
> 
> This is crashing in some cases.  IR attached.
> 
> The crash is here:
> 
>     MachineInstr *Shift = User.MI->getPrevNode();
>      if (Shift->getOpcode() != ARM::tLSLri ||
>          Shift->getOperand(3).getImm() != 2 ||
>          !Shift->getOperand(2).isKill())
>        continue;
> 
> I think the problem is that you're incorrectly assuming that tLEApcrelJT isn't the first instruction in a basic block.
> 
> -Eli
> 
> -- 
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
> 
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