[PATCH] D21007: DSE: Don't remove stores made live by a call which unwinds.

[Hal Finkel via llvm-commits]

hfinkel added inline comments.

================
Comment at: lib/Transforms/Scalar/DeadStoreElimination.cpp:860
@@ +859,3 @@
+      // the store.
+      // FIXME: Check whether a throwing call is actually between the stores, instead
+      // of just in the same block.  Maybe using OrderedBasicBlock?
----------------
eli.friedman wrote:
> hfinkel wrote:
> > Not clear that OrderedBasicBlock will help here directly. I think you really want two maps:
> > 
> >  1. Instruction* -> unsigned (for ordering)
> >  2. Instruction* -> Instruction* (or unsigned) (for the next call that might throw)
> > 
> > Why not just collect the maps above (where you currently set MayThrow), and then answer the question precisely? I think it is likely I'll see performance regressions from this if we over-approximate.
> Yes, I can do something like that. Not sure the second map is necessary: I think we just need the most recently seen unwinding call in the block?
Ah, yes. You're right. Thanks!



http://reviews.llvm.org/D21007