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implement visitBR_CC so that PowerPC/inverted-bool-compares.ll passes

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with the dag combiner.  This speeds up espresso by 8%, reaching performance
parity with the dag-combiner-disabled llc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23636 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-05 06:47:48 +00:00
parent ad13715ed4
commit 3ea0b47f81
2 changed files with 25 additions and 2 deletions
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24
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -1425,9 +1425,29 @@ SDOperand DAGCombiner::visitBRCONDTWOWAY(SDNode *N) {
return SDOperand();
}
// Operand List for BR_CC: Chain, CondCC, CondLHS, CondRHS, DestBB.
//
SDOperand DAGCombiner::visitBR_CC(SDNode *N) {
// FIXME: come up with a common way between br_cc, brtwoway_cc, and select_cc
// to canonicalize the condition without calling getnode a bazillion times.
CondCodeSDNode *CC = cast<CondCodeSDNode>(N->getOperand(1));
SDOperand CondLHS = N->getOperand(2), CondRHS = N->getOperand(3);
// Use SimplifySetCC to simplify SETCC's.
SDOperand Simp = SimplifySetCC(MVT::i1, CondLHS, CondRHS, CC->get());
if (Simp.Val) {
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Simp)) {
if (C->getValue() & 1) // Unconditional branch
return DAG.getNode(ISD::BR, MVT::Other, N->getOperand(0),
N->getOperand(4));
else
return N->getOperand(0); // Unconditional Fall through
} else if (Simp.Val->getOpcode() == ISD::SETCC) {
// Folded to a simpler setcc
return DAG.getNode(ISD::BR_CC, MVT::Other, N->getOperand(0),
Simp.getOperand(2), Simp.getOperand(0),
Simp.getOperand(1), N->getOperand(4));
}
}
return SDOperand();
}

3
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -1963,6 +1963,9 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
assert(Ops.size() == 5 && "BR_CC takes 5 operands!");
assert(Ops[2].getValueType() == Ops[3].getValueType() &&
"LHS/RHS of comparison should match types!");
if (CombinerEnabled) break; // xforms moved to dag combine.
// Use SimplifySetCC to simplify SETCC's.
SDOperand Simp = SimplifySetCC(MVT::i1, Ops[2], Ops[3],
cast<CondCodeSDNode>(Ops[1])->get());