Use sbb x, x to materialize carry bit in a GPR. The result is all one's or all zero's.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91381 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 99f9845..14908b4 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -5750,6 +5750,15 @@
return SDValue();
SDValue Cond = EmitCmp(Op0, Op1, X86CC, DAG);
+
+ // Use sbb x, x to materialize carry bit into a GPR.
+ if (X86CC == X86::COND_B) {
+ return DAG.getNode(ISD::AND, dl, MVT::i8,
+ DAG.getNode(X86ISD::SETCC_CARRY, dl, MVT::i8,
+ DAG.getConstant(X86CC, MVT::i8), Cond),
+ DAG.getConstant(1, MVT::i8));
+ }
+
return DAG.getNode(X86ISD::SETCC, dl, MVT::i8,
DAG.getConstant(X86CC, MVT::i8), Cond);
}
@@ -5902,9 +5911,18 @@
Cond = NewCond;
}
+ // Look pass (and (setcc_carry (cmp ...)), 1).
+ if (Cond.getOpcode() == ISD::AND &&
+ Cond.getOperand(0).getOpcode() == X86ISD::SETCC_CARRY) {
+ ConstantSDNode *C = dyn_cast<ConstantSDNode>(Cond.getOperand(1));
+ if (C && C->getAPIntValue() == 1)
+ Cond = Cond.getOperand(0);
+ }
+
// If condition flag is set by a X86ISD::CMP, then use it as the condition
// setting operand in place of the X86ISD::SETCC.
- if (Cond.getOpcode() == X86ISD::SETCC) {
+ if (Cond.getOpcode() == X86ISD::SETCC ||
+ Cond.getOpcode() == X86ISD::SETCC_CARRY) {
CC = Cond.getOperand(0);
SDValue Cmp = Cond.getOperand(1);
@@ -5987,9 +6005,18 @@
Cond = LowerXALUO(Cond, DAG);
#endif
+ // Look pass (and (setcc_carry (cmp ...)), 1).
+ if (Cond.getOpcode() == ISD::AND &&
+ Cond.getOperand(0).getOpcode() == X86ISD::SETCC_CARRY) {
+ ConstantSDNode *C = dyn_cast<ConstantSDNode>(Cond.getOperand(1));
+ if (C && C->getAPIntValue() == 1)
+ Cond = Cond.getOperand(0);
+ }
+
// If condition flag is set by a X86ISD::CMP, then use it as the condition
// setting operand in place of the X86ISD::SETCC.
- if (Cond.getOpcode() == X86ISD::SETCC) {
+ if (Cond.getOpcode() == X86ISD::SETCC ||
+ Cond.getOpcode() == X86ISD::SETCC_CARRY) {
CC = Cond.getOperand(0);
SDValue Cmp = Cond.getOperand(1);
@@ -7376,6 +7403,7 @@
case X86ISD::COMI: return "X86ISD::COMI";
case X86ISD::UCOMI: return "X86ISD::UCOMI";
case X86ISD::SETCC: return "X86ISD::SETCC";
+ case X86ISD::SETCC_CARRY: return "X86ISD::SETCC_CARRY";
case X86ISD::CMOV: return "X86ISD::CMOV";
case X86ISD::BRCOND: return "X86ISD::BRCOND";
case X86ISD::RET_FLAG: return "X86ISD::RET_FLAG";
@@ -8950,11 +8978,42 @@
return SDValue();
}
+static SDValue PerformSHLCombine(SDNode *N, SelectionDAG &DAG) {
+ SDValue N0 = N->getOperand(0);
+ SDValue N1 = N->getOperand(1);
+ ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
+ EVT VT = N0.getValueType();
+
+ // fold (shl (and (setcc_c), c1), c2) -> (and setcc_c, (c1 << c2))
+ // since the result of setcc_c is all zero's or all ones.
+ if (N1C && N0.getOpcode() == ISD::AND &&
+ N0.getOperand(1).getOpcode() == ISD::Constant) {
+ SDValue N00 = N0.getOperand(0);
+ if (N00.getOpcode() == X86ISD::SETCC_CARRY ||
+ ((N00.getOpcode() == ISD::ANY_EXTEND ||
+ N00.getOpcode() == ISD::ZERO_EXTEND) &&
+ N00.getOperand(0).getOpcode() == X86ISD::SETCC_CARRY)) {
+ APInt Mask = cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue();
+ APInt ShAmt = N1C->getAPIntValue();
+ Mask = Mask.shl(ShAmt);
+ if (Mask != 0)
+ return DAG.getNode(ISD::AND, N->getDebugLoc(), VT,
+ N00, DAG.getConstant(Mask, VT));
+ }
+ }
+
+ return SDValue();
+}
/// PerformShiftCombine - Transforms vector shift nodes to use vector shifts
/// when possible.
static SDValue PerformShiftCombine(SDNode* N, SelectionDAG &DAG,
const X86Subtarget *Subtarget) {
+ EVT VT = N->getValueType(0);
+ if (!VT.isVector() && VT.isInteger() &&
+ N->getOpcode() == ISD::SHL)
+ return PerformSHLCombine(N, DAG);
+
// On X86 with SSE2 support, we can transform this to a vector shift if
// all elements are shifted by the same amount. We can't do this in legalize
// because the a constant vector is typically transformed to a constant pool
@@ -8962,7 +9021,6 @@
if (!Subtarget->hasSSE2())
return SDValue();
- EVT VT = N->getValueType(0);
if (VT != MVT::v2i64 && VT != MVT::v4i32 && VT != MVT::v8i16)
return SDValue();