Sanjoy Das c83e065234 [SCEV] Clarify behavior around max backedge taken count ... This is a re-application of a r303497 that was reverted in r303498. I thought it had broken a bot when it had not (the breakage did not go away with the revert). This change makes the split between the "exact" backedge taken count and the "maximum" backedge taken count a bit more obvious. Both of these are upper bounds on the number of times the loop header executes (since SCEV does not account for most kinds of abnormal control flow), but the latter is guaranteed to be a constant. There were a few places where the max backedge taken count *was* a non-constant; I've changed those to compute constants instead. At this point, I'm not sure if the constant max backedge count can be computed by calling `getUnsignedRange(Exact).getUnsignedMax()` without losing precision. If it can, we can simplify even further by making `getMaxBackedgeTakenCount` a thin wrapper around `getBackedgeTakenCount` and `getUnsignedRange`. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303531 91177308-0d34-0410-b5e6-96231b3b80d8		2017-05-22 06:46:04 +00:00
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llvm	[SCEV] Clarify behavior around max backedge taken count	2017-05-22 06:46:04 +00:00
llvm-c	Introduce LLVMDIBuilderRef	2017-04-20 14:22:47 +00:00