implement visitBR_CC so that PowerPC/inverted-bool-compares.ll passes
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
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 26504df..23d9b43 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1425,9 +1425,29 @@
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();
}
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 35b6b57..f1d81bc 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1963,6 +1963,9 @@
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());