From 3ea0b47f81caeb53f9594dd3f7702ae01c4f2cc6 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Wed, 5 Oct 2005 06:47:48 +0000 Subject: 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 --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) (limited to 'lib/CodeGen/SelectionDAG/DAGCombiner.cpp') diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 26504df265..23d9b432c3 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -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(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(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(); } -- cgit v1.2.3