David Green 49873f2449 [Analysis] TTI: Add CastContextHint for getCastInstrCost ... Currently, getCastInstrCost has limited information about the cast it's rating, often just the opcode and types. Sometimes there is a context instruction as well, but it isn't trustworthy: for instance, when the vectorizer is rating a plan, it calls getCastInstrCost with the old instructions when, in fact, it's trying to evaluate the cost of the instruction post-vectorization. Thus, the current system can get the cost of certain casts incorrect as the correct cost can vary greatly based on the context in which it's used. For example, if the vectorizer queries getCastInstrCost to evaluate the cost of a sext(load) with tail predication enabled, getCastInstrCost will think it's free most of the time, but it's not always free. On ARM MVE, a VLD2 group cannot be extended like a normal VLDR can. Similar situations can come up with how masked loads can be extended when being split. To fix that, this path adds a new parameter to getCastInstrCost to give it a hint about the context of the cast. It adds a CastContextHint enum which contains the type of the load/store being created by the vectorizer - one for each of the types it can produce. Original patch by Pierre van Houtryve Differential Revision: https://reviews.llvm.org/D79162		2020-07-29 13:32:53 +01:00
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llvm	[Analysis] TTI: Add CastContextHint for getCastInstrCost	2020-07-29 13:32:53 +01:00
llvm-c	[BFloat] Move LLVMBFloatTypeKind to the end of the enum	2020-06-19 01:51:44 +01:00