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author | Richard Sandiford <rsandifo@linux.vnet.ibm.com> | 2013-12-10 10:36:34 +0000 |
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committer | Richard Sandiford <rsandifo@linux.vnet.ibm.com> | 2013-12-10 10:36:34 +0000 |
commit | 086791eca2260c03c7bbdd37a53626d16656f0ca (patch) | |
tree | 338587b3a572be6708a71a39c22332bea08ca0a4 /lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | |
parent | faeef98cbcd1b8e1830b3ced48e85dd77c1b71b8 (diff) | |
download | llvm-086791eca2260c03c7bbdd37a53626d16656f0ca.tar.gz llvm-086791eca2260c03c7bbdd37a53626d16656f0ca.tar.bz2 llvm-086791eca2260c03c7bbdd37a53626d16656f0ca.tar.xz |
Add TargetLowering::prepareVolatileOrAtomicLoad
One unusual feature of the z architecture is that the result of a
previous load can be reused indefinitely for subsequent loads, even if
a cache-coherent store to that location is performed by another CPU.
A special serializing instruction must be used if you want to force
a load to be reattempted.
Since volatile loads are not supposed to be omitted in this way,
we should insert a serializing instruction before each such load.
The same goes for atomic loads.
The patch implements this at the IR->DAG boundary, in a similar way
to atomic fences. It is a no-op for targets other than SystemZ.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196905 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp')
-rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index 34b7df59ac..c63a88b9d7 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -3400,7 +3400,7 @@ void SelectionDAGBuilder::visitLoad(const LoadInst &I) { SDValue Root; bool ConstantMemory = false; - if (I.isVolatile() || NumValues > MaxParallelChains) + if (isVolatile || NumValues > MaxParallelChains) // Serialize volatile loads with other side effects. Root = getRoot(); else if (AA->pointsToConstantMemory( @@ -3413,6 +3413,10 @@ void SelectionDAGBuilder::visitLoad(const LoadInst &I) { Root = DAG.getRoot(); } + const TargetLowering *TLI = TM.getTargetLowering(); + if (isVolatile) + Root = TLI->prepareVolatileOrAtomicLoad(Root, getCurSDLoc(), DAG); + SmallVector<SDValue, 4> Values(NumValues); SmallVector<SDValue, 4> Chains(std::min(unsigned(MaxParallelChains), NumValues)); @@ -3637,6 +3641,7 @@ void SelectionDAGBuilder::visitAtomicLoad(const LoadInst &I) { if (I.getAlignment() < VT.getSizeInBits() / 8) report_fatal_error("Cannot generate unaligned atomic load"); + InChain = TLI->prepareVolatileOrAtomicLoad(InChain, dl, DAG); SDValue L = DAG.getAtomic(ISD::ATOMIC_LOAD, dl, VT, VT, InChain, getValue(I.getPointerOperand()), |