[PATCH] D40554: [PowerPC] Fix bugs in sign-/zero-extension elimination

[Hiroshi Inoue via Phabricator via llvm-commits]

inouehrs marked an inline comment as done.
inouehrs added inline comments.


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Comment at: lib/Target/PowerPC/PPCInstrInfo.h:343
 
-  bool isSignOrZeroExtended(const MachineInstr &MI, bool SignExt,
-                            const unsigned PhiDepth) const;
+  bool isSignOrZeroExtended(const unsigned Reg, bool SignExt,
+                            const unsigned PhiDepth,
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nemanjai wrote:
> inouehrs wrote:
> > nemanjai wrote:
> > > I still think this setup with separate queries for sign/zero/any extend seems unnecessarily complex. Seems like it would be clearer if we had an enum for the extension type (sign, zero, none) and we just have a single query that will return this. Therefore no need for Boolean parameters, no need for multiple functions, etc.
> > I agree that the single query approach is cleaner. But I am afraid that it will increase the cost of compilation slightly since it always checks for both sign- and zero-extensions. Do you think the potential increase in compilation cost does not matter too much here?
> It seems to me that the checks are not costly except in chained operations cases (which we traverse the chain as it is). Or am I missing something. What is the worst case complexity of the computations for each?
Thanks. I modified the helper to return `std::pair<bool, bool>`. 
Do you prefer an enum?


https://reviews.llvm.org/D40554