Move 3 "(add (select cc, 0, c), x) -> (select cc, x, (add, x, c))"
related transformations out of target-specific dag combine into the
ARM backend. These were added by Evan in r37685 with no testcases
and only seems to help ARM (e.g. test/CodeGen/ARM/select_xform.ll).
Add some simple X86-specific (for now) DAG combines that turn things
like cond ? 8 : 0 -> (zext(cond) << 3). This happens frequently
with the recently added cp constant select optimization, but is a
very general xform. For example, we now compile the second example
in const-select.ll to:
_test:
movsd LCPI2_0, %xmm0
ucomisd 8(%esp), %xmm0
seta %al
movzbl %al, %eax
movl 4(%esp), %ecx
movsbl (%ecx,%eax,4), %eax
ret
instead of:
_test:
movl 4(%esp), %eax
leal 4(%eax), %ecx
movsd LCPI2_0, %xmm0
ucomisd 8(%esp), %xmm0
cmovbe %eax, %ecx
movsbl (%ecx), %eax
ret
This passes multisource and dejagnu.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66779 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index a6674b2..25dda0c 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -256,7 +256,10 @@
// We have target-specific dag combine patterns for the following nodes:
// ARMISD::FMRRD - No need to call setTargetDAGCombine
-
+ setTargetDAGCombine(ISD::ADD);
+ setTargetDAGCombine(ISD::SUB);
+
+
setStackPointerRegisterToSaveRestore(ARM::SP);
setSchedulingPreference(SchedulingForRegPressure);
setIfCvtBlockSizeLimit(Subtarget->isThumb() ? 0 : 10);
@@ -1562,6 +1565,102 @@
// ARM Optimization Hooks
//===----------------------------------------------------------------------===//
+static
+SDValue combineSelectAndUse(SDNode *N, SDValue Slct, SDValue OtherOp,
+ TargetLowering::DAGCombinerInfo &DCI) {
+
+ SelectionDAG &DAG = DCI.DAG;
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+ MVT VT = N->getValueType(0);
+ unsigned Opc = N->getOpcode();
+ bool isSlctCC = Slct.getOpcode() == ISD::SELECT_CC;
+ SDValue LHS = isSlctCC ? Slct.getOperand(2) : Slct.getOperand(1);
+ SDValue RHS = isSlctCC ? Slct.getOperand(3) : Slct.getOperand(2);
+ ISD::CondCode CC = ISD::SETCC_INVALID;
+
+ if (isSlctCC) {
+ CC = cast<CondCodeSDNode>(Slct.getOperand(4))->get();
+ } else {
+ SDValue CCOp = Slct.getOperand(0);
+ if (CCOp.getOpcode() == ISD::SETCC)
+ CC = cast<CondCodeSDNode>(CCOp.getOperand(2))->get();
+ }
+
+ bool DoXform = false;
+ bool InvCC = false;
+ assert ((Opc == ISD::ADD || (Opc == ISD::SUB && Slct == N->getOperand(1))) &&
+ "Bad input!");
+
+ if (LHS.getOpcode() == ISD::Constant &&
+ cast<ConstantSDNode>(LHS)->isNullValue()) {
+ DoXform = true;
+ } else if (CC != ISD::SETCC_INVALID &&
+ RHS.getOpcode() == ISD::Constant &&
+ cast<ConstantSDNode>(RHS)->isNullValue()) {
+ std::swap(LHS, RHS);
+ SDValue Op0 = Slct.getOperand(0);
+ MVT OpVT = isSlctCC ? Op0.getValueType() :
+ Op0.getOperand(0).getValueType();
+ bool isInt = OpVT.isInteger();
+ CC = ISD::getSetCCInverse(CC, isInt);
+
+ if (!TLI.isCondCodeLegal(CC, OpVT))
+ return SDValue(); // Inverse operator isn't legal.
+
+ DoXform = true;
+ InvCC = true;
+ }
+
+ if (DoXform) {
+ SDValue Result = DAG.getNode(Opc, RHS.getDebugLoc(), VT, OtherOp, RHS);
+ if (isSlctCC)
+ return DAG.getSelectCC(N->getDebugLoc(), OtherOp, Result,
+ Slct.getOperand(0), Slct.getOperand(1), CC);
+ SDValue CCOp = Slct.getOperand(0);
+ if (InvCC)
+ CCOp = DAG.getSetCC(Slct.getDebugLoc(), CCOp.getValueType(),
+ CCOp.getOperand(0), CCOp.getOperand(1), CC);
+ return DAG.getNode(ISD::SELECT, N->getDebugLoc(), VT,
+ CCOp, OtherOp, Result);
+ }
+ return SDValue();
+}
+
+/// PerformADDCombine - Target-specific dag combine xforms for ISD::ADD.
+static SDValue PerformADDCombine(SDNode *N,
+ TargetLowering::DAGCombinerInfo &DCI) {
+ // added by evan in r37685 with no testcase.
+ SDValue N0 = N->getOperand(0), N1 = N->getOperand(1);
+
+ // fold (add (select cc, 0, c), x) -> (select cc, x, (add, x, c))
+ if (N0.getOpcode() == ISD::SELECT && N0.getNode()->hasOneUse()) {
+ SDValue Result = combineSelectAndUse(N, N0, N1, DCI);
+ if (Result.getNode()) return Result;
+ }
+ if (N1.getOpcode() == ISD::SELECT && N1.getNode()->hasOneUse()) {
+ SDValue Result = combineSelectAndUse(N, N1, N0, DCI);
+ if (Result.getNode()) return Result;
+ }
+
+ return SDValue();
+}
+
+/// PerformSUBCombine - Target-specific dag combine xforms for ISD::SUB.
+static SDValue PerformSUBCombine(SDNode *N,
+ TargetLowering::DAGCombinerInfo &DCI) {
+ // added by evan in r37685 with no testcase.
+ SDValue N0 = N->getOperand(0), N1 = N->getOperand(1);
+
+ // fold (sub x, (select cc, 0, c)) -> (select cc, x, (sub, x, c))
+ if (N1.getOpcode() == ISD::SELECT && N1.getNode()->hasOneUse()) {
+ SDValue Result = combineSelectAndUse(N, N1, N0, DCI);
+ if (Result.getNode()) return Result;
+ }
+
+ return SDValue();
+}
+
+
/// PerformFMRRDCombine - Target-specific dag combine xforms for ARMISD::FMRRD.
static SDValue PerformFMRRDCombine(SDNode *N,
TargetLowering::DAGCombinerInfo &DCI) {
@@ -1576,6 +1675,8 @@
DAGCombinerInfo &DCI) const {
switch (N->getOpcode()) {
default: break;
+ case ISD::ADD: return PerformADDCombine(N, DCI);
+ case ISD::SUB: return PerformSUBCombine(N, DCI);
case ARMISD::FMRRD: return PerformFMRRDCombine(N, DCI);
}