From e5d9515fb71bc6655cfbb2ef8ce000891aade2b1 Mon Sep 17 00:00:00 2001 From: Matt Arsenault Date: Tue, 13 Oct 2015 00:49:00 +0000 Subject: DAGCombiner: Don't stop finding better chain on 2 aliases The comment says this was stopped because it was unlikely to be profitable. This is not true if you want to combine vector loads with multiple components. For a simple case that looks like t0 = load t0 ... t1 = load t0 ... t2 = load t0 ... t3 = load t0 ... t4 = store t0:1, t0:1 t5 = store t4, t1:0 t6 = store t5, t2:0 t7 = store t6, t3:0 We want to get all of these stores onto a chain that is a TokenFactor of these N loads. This mostly solves the AMDGPU merge-stores.ll regressions with -combiner-alias-analysis for merging vector stores of vector loads. llvm-svn: 250138 --- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp') diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index a26f378b49a..b9b37fd0be8 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -14298,14 +14298,12 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain, SDValue Chain = Chains.pop_back_val(); // For TokenFactor nodes, look at each operand and only continue up the - // chain until we find two aliases. If we've seen two aliases, assume we'll - // find more and revert to original chain since the xform is unlikely to be - // profitable. + // chain until we reach the depth limit. // // FIXME: The depth check could be made to return the last non-aliasing // chain we found before we hit a tokenfactor rather than the original // chain. - if (Depth > 6 || Aliases.size() == 2) { + if (Depth > 6) { Aliases.clear(); Aliases.push_back(OriginalChain); return; -- cgit v1.2.3