From db65a5b776f20795df41741bc7042d6b61070886 Mon Sep 17 00:00:00 2001 From: Philip Reames Date: Tue, 19 Mar 2019 18:27:18 +0000 Subject: Allow unordered loads to be considered invariant in CodeGen The actual code change is fairly straight forward, but exercising it isn't. First, it turned out we weren't adding the appropriate flags in SelectionDAG. Second, it turned out that we've got some optimization gaps, so obvious test cases don't work. My first attempt (in atomic-unordered.ll) points out a deficiency in our peephole-opt folding logic which I plan to fix separately. Instead, I'm exercising this through MachineLICM. Differential Revision: https://reviews.llvm.org/D59375 llvm-svn: 356494 --- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp') diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index 3aedee8db0b..6d7f2840adf 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -4564,6 +4564,11 @@ void SelectionDAGBuilder::visitAtomicLoad(const LoadInst &I) { auto Flags = MachineMemOperand::MOLoad; if (I.isVolatile()) Flags |= MachineMemOperand::MOVolatile; + if (I.getMetadata(LLVMContext::MD_invariant_load) != nullptr) + Flags |= MachineMemOperand::MOInvariant; + if (isDereferenceablePointer(I.getPointerOperand(), DAG.getDataLayout())) + Flags |= MachineMemOperand::MODereferenceable; + Flags |= TLI.getMMOFlags(I); MachineMemOperand *MMO = -- cgit v1.2.3