Define patterns for shld and shrd that match immediate
shift counts, and patterns that match dynamic shift counts
when the subtract is obscured by a truncate node.
Add DAGCombiner support for recognizing rotate patterns
when the shift counts are defined by truncate nodes.
Fix and simplify the code for commuting shld and shrd
instructions to work even when the given instruction doesn't
have a parent, and when the caller needs a new instruction.
These changes allow LLVM to use the shld, shrd, rol, and ror
instructions on x86 to replace equivalent code using two
shifts and an or in many more cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57662 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index f546ed4..4b1945e 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2053,13 +2053,15 @@
}
}
- // Look for sign/zext/any-extended cases:
+ // Look for sign/zext/any-extended or truncate cases:
if ((LHSShiftAmt.getOpcode() == ISD::SIGN_EXTEND
|| LHSShiftAmt.getOpcode() == ISD::ZERO_EXTEND
- || LHSShiftAmt.getOpcode() == ISD::ANY_EXTEND) &&
+ || LHSShiftAmt.getOpcode() == ISD::ANY_EXTEND
+ || LHSShiftAmt.getOpcode() == ISD::TRUNCATE) &&
(RHSShiftAmt.getOpcode() == ISD::SIGN_EXTEND
|| RHSShiftAmt.getOpcode() == ISD::ZERO_EXTEND
- || RHSShiftAmt.getOpcode() == ISD::ANY_EXTEND)) {
+ || RHSShiftAmt.getOpcode() == ISD::ANY_EXTEND
+ || RHSShiftAmt.getOpcode() == ISD::TRUNCATE)) {
SDValue LExtOp0 = LHSShiftAmt.getOperand(0);
SDValue RExtOp0 = RHSShiftAmt.getOperand(0);
if (RExtOp0.getOpcode() == ISD::SUB &&
@@ -2068,7 +2070,8 @@
// (rotl x, y)
// fold (or (shl x, (*ext y)), (srl x, (*ext (sub 32, y)))) ->
// (rotr x, (sub 32, y))
- if (ConstantSDNode *SUBC = cast<ConstantSDNode>(RExtOp0.getOperand(0))) {
+ if (ConstantSDNode *SUBC =
+ dyn_cast<ConstantSDNode>(RExtOp0.getOperand(0))) {
if (SUBC->getAPIntValue() == OpSizeInBits) {
return DAG.getNode(HasROTL ? ISD::ROTL : ISD::ROTR, VT, LHSShiftArg,
HasROTL ? LHSShiftAmt : RHSShiftAmt).getNode();
@@ -2080,7 +2083,8 @@
// (rotr x, y)
// fold (or (shl x, (*ext (sub 32, y))), (srl x, (*ext y))) ->
// (rotl x, (sub 32, y))
- if (ConstantSDNode *SUBC = cast<ConstantSDNode>(LExtOp0.getOperand(0))) {
+ if (ConstantSDNode *SUBC =
+ dyn_cast<ConstantSDNode>(LExtOp0.getOperand(0))) {
if (SUBC->getAPIntValue() == OpSizeInBits) {
return DAG.getNode(HasROTR ? ISD::ROTR : ISD::ROTL, VT, LHSShiftArg,
HasROTR ? RHSShiftAmt : LHSShiftAmt).getNode();