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author | Nate Begeman <natebegeman@mac.com> | 2005-10-12 23:18:53 +0000 |
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committer | Nate Begeman <natebegeman@mac.com> | 2005-10-12 23:18:53 +0000 |
commit | 765784ad760ee6cc504d79e4966c272387c313f8 (patch) | |
tree | e0f651e36f6f372cef2cbebae9c9f0cc15fc68cd /lib | |
parent | 3df4d525c58d5db878eaadcfdcffbbfca96dd6a2 (diff) | |
download | external_llvm-765784ad760ee6cc504d79e4966c272387c313f8.zip external_llvm-765784ad760ee6cc504d79e4966c272387c313f8.tar.gz external_llvm-765784ad760ee6cc504d79e4966c272387c313f8.tar.bz2 |
Fix a potential bug with two combine-to's back to back that chris pointed
out, where after the first CombineTo() call, the node the second CombineTo
wishes to replace may no longer exist.
Fix a very real bug with the truncated load optimization on little endian
targets, which do not need a byte offset added to the load.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23704 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index d5dbf3c..e254811 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1194,13 +1194,17 @@ SDOperand DAGCombiner::visitSIGN_EXTEND(SDNode *N) { // fold (sext (sext x)) -> (sext x) if (N0.getOpcode() == ISD::SIGN_EXTEND) return DAG.getNode(ISD::SIGN_EXTEND, VT, N0.getOperand(0)); + // fold (sext (sextload x)) -> (sextload x) + if (N0.getOpcode() == ISD::SEXTLOAD && VT == N0.getValueType()) + return N0; // fold (sext (load x)) -> (sextload x) if (N0.getOpcode() == ISD::LOAD && N0.Val->hasNUsesOfValue(1, 0)) { SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, N0.getOperand(0), N0.getOperand(1), N0.getOperand(2), N0.getValueType()); CombineTo(N0.Val, ExtLoad, ExtLoad.getOperand(0)); - return CombineTo(N, ExtLoad); + WorkList.push_back(N); + return SDOperand(); } return SDOperand(); } @@ -1303,13 +1307,19 @@ SDOperand DAGCombiner::visitTRUNCATE(SDNode *N) { assert(MVT::getSizeInBits(N0.getValueType()) > MVT::getSizeInBits(VT) && "Cannot truncate to larger type!"); MVT::ValueType PtrType = N0.getOperand(1).getValueType(); + // For big endian targets, we need to add an offset to the pointer to load + // the correct bytes. For little endian systems, we merely need to read + // fewer bytes from the same pointer. uint64_t PtrOff = (MVT::getSizeInBits(N0.getValueType()) - MVT::getSizeInBits(VT)) / 8; - SDOperand NewPtr = DAG.getNode(ISD::ADD, PtrType, N0.getOperand(1), - DAG.getConstant(PtrOff, PtrType)); + SDOperand NewPtr = TLI.isLittleEndian() ? N0.getOperand(1) : + DAG.getNode(ISD::ADD, PtrType, N0.getOperand(1), + DAG.getConstant(PtrOff, PtrType)); + WorkList.push_back(NewPtr.Val); SDOperand Load = DAG.getLoad(VT, N0.getOperand(0), NewPtr,N0.getOperand(2)); CombineTo(N0.Val, Load, Load.getOperand(0)); - return CombineTo(N, Load); + WorkList.push_back(N); + return SDOperand(); } return SDOperand(); } |