[PATCH] D46278: [AArch64] Fold B = csel A, A into B = COPY A

[Jon Roelofs via Phabricator via llvm-commits]

jroelofs added inline comments.


================
Comment at: llvm/lib/Target/AArch64/AArch64InstrInfo.cpp:920
+    if (TrueDef && FalseDef)
+      return TrueDef == FalseDef;
+
----------------
dmgreen wrote:
> jroelofs wrote:
> > I found a case that throws a wrench in this strategy:
> > 
> > ```
> > early-clobber %66:gpr64common, %67:gpr64 = LDRXpre %38:gpr64common(tied-def 0), 16
> > %74:gpr64 = CSELXr killed %67:gpr64, %66:gpr64common, 11, implicit $nzcv
> > 
> > ```
> Does that apply to D101508 too?
It does, yeah. I'm adjusting that patch as we speak :)


Repository:
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  https://reviews.llvm.org/D46278/new/

https://reviews.llvm.org/D46278