[WIP][DAG] visitFREEZE - always allow freezing multiple operands #152107
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Aug 22, 2025
…te poison/undef Add AMDGPUTargetLowering::canCreateUndefOrPoisonForTargetNode handler and tag BFE_I32/U32 nodes as they can only propagate poison, not create poison/undef. Fighting some of the remaining regressions in llvm#152107 - need advice on the v_round_f64 change
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Aug 26, 2025
…2P8AFFINEQB / GF2P8MULB handling All 3 instructions are well defined bit twiddling operations - they do not introduce undef/poison with well defined inputs. Fixes regressions in llvm#152107
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…NLOG handling Basic bitlogic operations don't create undef/poison. Its proving really annoying to create proper test coverage for these specific opcodes as they tend to appear in later stages - their presence does help in some upcoming patches (e.g. llvm#152107) and I'd prefer to get them committed early.
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…NLOG handling (#155600) Basic bitlogic operations don't create undef/poison. Its proving really annoying to create proper test coverage for these specific opcodes as they tend to appear in later stages - their presence does help in some upcoming patches (e.g. #152107) and I'd prefer to get them committed early.
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Remove the limited freeze multiple operand handling, always freeze all operands and rely on later visitFREEZE calls to merge frozen/unfrozen versions of each node to prevent infinite loops. This also removes the special handling of frozen SRA/SRL nodes as most of the regressions are related Fixes llvm#149798 Fixes llvm#150204
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Sep 29, 2025
…directly freeze all operands Avoid the ReplaceAllUsesOfValueWith approach that has caused so many problems in previous attempts at this (llvm#145939). Minor step towards llvm#149798 - eventually we're just going to use this path for all node types, but there's a large number of regressions that need addressing first (see llvm#152107). This exposed a couple of things that need to be addressed here: - we need to revisit frozen nodes once we've merged all frozen/unfrozen uses of a node. - RISCVISD::READ_VLENB is never undef/poison Many of the current regressions are due to us not doing more to avoid freeze(load) nodes - if the load is legal, its no longer going to split. I'm not certain exactly when we can split nodes - llvm#160884 tried to catch up to ValueTracking but that might still be wrong.
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Remove the limited freeze multiple operand handling, always freeze all operands and rely on later visitFREEZE calls to merge frozen/unfrozen versions of each node to prevent infinite loops.
This also removes the special handling of frozen SRA/SRL nodes as most of the regressions are related
Fixes #149798
Fixes #150204