[llvm-commits] [llvm] r74991 - in /llvm/trunk: docs/ include/llvm-c/ include/llvm/ include/llvm/Bitcode/ include/llvm/Support/ lib/Analysis/ lib/AsmParser/ lib/Bitcode/Reader/ lib/Bitcode/Writer/ lib/CodeGen/SelectionDAG/ lib/Target/ARM/ lib/Tran

[Chris Lattner]

On Jul 8, 2009, at 11:59 AM, Nick Lewycky wrote:

>
> Can this just be removed?
>
> No. The code as released in LLVM 2.5 had basically no correlation  
> between whether the instruction was [if]cmp or v[if]cmp and whether  
> INST_CMP or INST_CMP2 was used. The comment was only there to  
> confuse the reader.
>
> As of this commit, we only generate INST_CMP2 which has a better  
> chance of being read correctly by previous versions of LLVM than if  
> we were to generate INST_CMP.
>
> To make matters worse, some 2.5 version bitcode files would contain  
> icmp (but not fcmp?) with a bad type, such as a constant expression  
> icmp that returns <4 x i32> instead of <4 x i1>. Such files will no  
> longer load with current LLVM; we could try to autoupgrade those but  
> I'm inclined to say "sorry, older LLVMs were buggy and produced bad  
> IR in rare circumstances" than to try to deal with it.

Ok.

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