Simon Pilgrim 96ae40c830 [SelectionDAG] computeKnownBits - support constant pool values from target ... This patch adds the overridable TargetLowering::getTargetConstantFromLoad function which allows targets to return any constant value loaded by a LoadSDNode node - only X86 makes use of this so far but everything should be in place for other targets. computeKnownBits then uses this function to improve codegen, notably vector code after legalization. A future commit will do the same for ComputeNumSignBits but computeKnownBits sees the bigger benefit. This required a couple of fixes: * SimplifyDemandedBits must early-out for getTargetConstantFromLoad cases to prevent infinite loops of constant regeneration (similar to what we already do for BUILD_VECTOR). * Fix a DAGCombiner::visitTRUNCATE issue as we had trunc(shl(v8i32),v8i16) <-> shl(trunc(v8i16),v8i32) infinite loops after legalization on AVX512 targets. Differential Revision: https://reviews.llvm.org/D61887 llvm-svn: 361620		2019-05-24 10:03:11 +00:00
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llvm	[SelectionDAG] computeKnownBits - support constant pool values from target	2019-05-24 10:03:11 +00:00
llvm-c	[ELF] Implement Dependent Libraries Feature	2019-05-17 03:44:15 +00:00