[llvm-commits] [llvm] r162177 - in /llvm/trunk: lib/Target/ARM/ARMISelLowering.cpp test/CodeGen/ARM/select_xform.ll
Jakob Stoklund Olesen
stoklund at 2pi.dk
Sat Aug 18 14:25:22 PDT 2012
Author: stoklund
Date: Sat Aug 18 16:25:22 2012
New Revision: 162177
URL: http://llvm.org/viewvc/llvm-project?rev=162177&view=rev
Log:
Also combine zext/sext into selects for ARM.
This turns common i1 patterns into predicated instructions:
(add (zext cc), x) -> (select cc (add x, 1), x)
(add (sext cc), x) -> (select cc (add x, -1), x)
For a function like:
unsigned f(unsigned s, int x) {
return s + (x>0);
}
We now produce:
cmp r1, #0
it gt
addgt.w r0, r0, #1
Instead of:
movs r2, #0
cmp r1, #0
it gt
movgt r2, #1
add r0, r2
Modified:
llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
llvm/trunk/test/CodeGen/ARM/select_xform.ll
Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=162177&r1=162176&r2=162177&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Sat Aug 18 16:25:22 2012
@@ -6981,6 +6981,65 @@
return AllOnes ? C->isAllOnesValue() : C->isNullValue();
}
+// Return true if N is conditionally 0 or all ones.
+// Detects these expressions where cc is an i1 value:
+//
+// (select cc 0, y) [AllOnes=0]
+// (select cc y, 0) [AllOnes=0]
+// (zext cc) [AllOnes=0]
+// (sext cc) [AllOnes=0/1]
+// (select cc -1, y) [AllOnes=1]
+// (select cc y, -1) [AllOnes=1]
+//
+// Invert is set when N is the null/all ones constant when CC is false.
+// OtherOp is set to the alternative value of N.
+static bool isConditionalZeroOrAllOnes(SDNode *N, bool AllOnes,
+ SDValue &CC, bool &Invert,
+ SDValue &OtherOp,
+ SelectionDAG &DAG) {
+ switch (N->getOpcode()) {
+ default: return false;
+ case ISD::SELECT: {
+ CC = N->getOperand(0);
+ SDValue N1 = N->getOperand(1);
+ SDValue N2 = N->getOperand(2);
+ if (isZeroOrAllOnes(N1, AllOnes)) {
+ Invert = false;
+ OtherOp = N2;
+ return true;
+ }
+ if (isZeroOrAllOnes(N2, AllOnes)) {
+ Invert = true;
+ OtherOp = N1;
+ return true;
+ }
+ return false;
+ }
+ case ISD::ZERO_EXTEND:
+ // (zext cc) can never be the all ones value.
+ if (AllOnes)
+ return false;
+ // Fall through.
+ case ISD::SIGN_EXTEND: {
+ EVT VT = N->getValueType(0);
+ CC = N->getOperand(0);
+ if (CC.getValueType() != MVT::i1)
+ return false;
+ Invert = !AllOnes;
+ if (AllOnes)
+ // When looking for an AllOnes constant, N is an sext, and the 'other'
+ // value is 0.
+ OtherOp = DAG.getConstant(0, VT);
+ else if (N->getOpcode() == ISD::ZERO_EXTEND)
+ // When looking for a 0 constant, N can be zext or sext.
+ OtherOp = DAG.getConstant(1, VT);
+ else
+ OtherOp = DAG.getConstant(APInt::getAllOnesValue(VT.getSizeInBits()), VT);
+ return true;
+ }
+ }
+}
+
// Combine a constant select operand into its use:
//
// (add (select cc, 0, c), x) -> (select cc, x, (add, x, c))
@@ -6992,6 +7051,13 @@
// The transform is rejected if the select doesn't have a constant operand that
// is null, or all ones when AllOnes is set.
//
+// Also recognize sext/zext from i1:
+//
+// (add (zext cc), x) -> (select cc (add x, 1), x)
+// (add (sext cc), x) -> (select cc (add x, -1), x)
+//
+// These transformations eventually create predicated instructions.
+//
// @param N The node to transform.
// @param Slct The N operand that is a select.
// @param OtherOp The other N operand (x above).
@@ -7003,53 +7069,24 @@
TargetLowering::DAGCombinerInfo &DCI,
bool AllOnes = false) {
SelectionDAG &DAG = DCI.DAG;
- const TargetLowering &TLI = DAG.getTargetLoweringInfo();
EVT 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;
+ SDValue NonConstantVal;
+ SDValue CCOp;
+ bool SwapSelectOps;
+ if (!isConditionalZeroOrAllOnes(Slct.getNode(), AllOnes, CCOp, SwapSelectOps,
+ NonConstantVal, DAG))
+ return SDValue();
+
+ // Slct is now know to be the desired identity constant when CC is true.
+ SDValue TrueVal = OtherOp;
+ SDValue FalseVal = DAG.getNode(N->getOpcode(), N->getDebugLoc(), VT,
+ OtherOp, NonConstantVal);
+ // Unless SwapSelectOps says CC should be false.
+ if (SwapSelectOps)
+ std::swap(TrueVal, FalseVal);
- 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;
- if (isZeroOrAllOnes(LHS, AllOnes)) {
- DoXform = true;
- } else if (CC != ISD::SETCC_INVALID && isZeroOrAllOnes(RHS, AllOnes)) {
- std::swap(LHS, RHS);
- SDValue Op0 = Slct.getOperand(0);
- EVT 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)
- return SDValue();
-
- 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);
+ CCOp, TrueVal, FalseVal);
}
// Attempt combineSelectAndUse on each operand of a commutative operator N.
@@ -7058,12 +7095,12 @@
TargetLowering::DAGCombinerInfo &DCI) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
- if (N0.getOpcode() == ISD::SELECT && N0.getNode()->hasOneUse()) {
+ if (N0.getNode()->hasOneUse()) {
SDValue Result = combineSelectAndUse(N, N0, N1, DCI, AllOnes);
if (Result.getNode())
return Result;
}
- if (N1.getOpcode() == ISD::SELECT && N1.getNode()->hasOneUse()) {
+ if (N1.getNode()->hasOneUse()) {
SDValue Result = combineSelectAndUse(N, N1, N0, DCI, AllOnes);
if (Result.getNode())
return Result;
@@ -7174,7 +7211,7 @@
return Result;
// fold (add (select cc, 0, c), x) -> (select cc, x, (add, x, c))
- if (N0.getOpcode() == ISD::SELECT && N0.getNode()->hasOneUse()) {
+ if (N0.getNode()->hasOneUse()) {
SDValue Result = combineSelectAndUse(N, N0, N1, DCI);
if (Result.getNode()) return Result;
}
@@ -7206,7 +7243,7 @@
SDValue 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()) {
+ if (N1.getNode()->hasOneUse()) {
SDValue Result = combineSelectAndUse(N, N1, N0, DCI);
if (Result.getNode()) return Result;
}
Modified: llvm/trunk/test/CodeGen/ARM/select_xform.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/select_xform.ll?rev=162177&r1=162176&r2=162177&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/select_xform.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/select_xform.ll Sat Aug 18 16:25:22 2012
@@ -190,3 +190,35 @@
ret void
}
declare void @bar(i8*)
+
+; Fold zext i1 into predicated add
+define i32 @t13(i32 %c, i32 %a) nounwind readnone ssp {
+entry:
+; ARM: t13
+; ARM: cmp r1, #10
+; ARM: addgt r0, r0, #1
+
+; T2: t13
+; T2: cmp r1, #10
+; T2: addgt.w r0, r0, #1
+ %cmp = icmp sgt i32 %a, 10
+ %conv = zext i1 %cmp to i32
+ %add = add i32 %conv, %c
+ ret i32 %add
+}
+
+; Fold sext i1 into predicated sub
+define i32 @t14(i32 %c, i32 %a) nounwind readnone ssp {
+entry:
+; ARM: t14
+; ARM: cmp r1, #10
+; ARM: subgt r0, r0, #1
+
+; T2: t14
+; T2: cmp r1, #10
+; T2: subgt.w r0, r0, #1
+ %cmp = icmp sgt i32 %a, 10
+ %conv = sext i1 %cmp to i32
+ %add = add i32 %conv, %c
+ ret i32 %add
+}
More information about the llvm-commits
mailing list