[PATCH] D21291: [SimplifyCFG] Range reduce switches
Eli Friedman via llvm-commits
llvm-commits at lists.llvm.org
Sun Jun 19 14:59:00 PDT 2016
eli.friedman added inline comments.
Comment at: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp:8332
@@ +8331,3 @@
+ C.Low = C.High = cast<ConstantInt>(CI);
Do we need to merge clusters in some cases, so we don't end up with adjacent clusters with the same destination? (This doesn't affect building a jump table, but it affects isDense.)
Hmm... actually, more generally, whether we transform a switch condition is to some extent independent of whether we form a jump table; for example, if we end up with one cluster here, you don't need a jump table at all. Maybe we can leave that for a followup, though.
Comment at: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h:267
@@ +266,3 @@
+ if (Shift == 0)
+ this->Base = First;
It's unintuitive to hide this in the constructor... it seems like a good idea to push the Shift == 0 special-case out.
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