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();
diff --git a/lib/Target/X86/X86ISelLowering.h b/lib/Target/X86/X86ISelLowering.h
index 89b773d..64bc70c 100644
--- a/lib/Target/X86/X86ISelLowering.h
+++ b/lib/Target/X86/X86ISelLowering.h
@@ -118,6 +118,10 @@
/// operand produced by a CMP instruction.
SETCC,
+ // Same as SETCC except it's materialized with a sbb and the value is all
+ // one's or all zero's.
+ SETCC_CARRY,
+
/// X86 conditional moves. Operand 0 and operand 1 are the two values
/// to select from. Operand 2 is the condition code, and operand 3 is the
/// flag operand produced by a CMP or TEST instruction. It also writes a
diff --git a/lib/Target/X86/X86Instr64bit.td b/lib/Target/X86/X86Instr64bit.td
index b5fa862..420d2db 100644
--- a/lib/Target/X86/X86Instr64bit.td
+++ b/lib/Target/X86/X86Instr64bit.td
@@ -1333,6 +1333,15 @@
X86_COND_NO, EFLAGS))]>, TB;
} // isTwoAddress
+// Use sbb to materialize carry flag into a GPR.
+let Defs = [EFLAGS], Uses = [EFLAGS], isCodeGenOnly = 1 in
+def SETB_C64r : RI<0x19, MRMDestReg, (outs GR64:$dst), (ins),
+ "sbb{q}\t$dst, $dst",
+ [(set GR64:$dst, (zext (X86setcc_c X86_COND_B, EFLAGS)))]>;
+
+def : Pat<(i64 (anyext (X86setcc_c X86_COND_B, EFLAGS))),
+ (SETB_C64r)>;
+
//===----------------------------------------------------------------------===//
// Conversion Instructions...
//
diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td
index f4a201c..3cc1853 100644
--- a/lib/Target/X86/X86InstrInfo.td
+++ b/lib/Target/X86/X86InstrInfo.td
@@ -87,6 +87,7 @@
def X86brcond : SDNode<"X86ISD::BRCOND", SDTX86BrCond,
[SDNPHasChain]>;
def X86setcc : SDNode<"X86ISD::SETCC", SDTX86SetCC>;
+def X86setcc_c : SDNode<"X86ISD::SETCC_CARRY", SDTX86SetCC>;
def X86cas : SDNode<"X86ISD::LCMPXCHG_DAG", SDTX86cas,
[SDNPHasChain, SDNPInFlag, SDNPOutFlag, SDNPMayStore,
@@ -3059,6 +3060,21 @@
def LAHF : I<0x9F, RawFrm, (outs), (ins), "lahf", []>; // AH = flags
let Uses = [EFLAGS] in {
+// Use sbb to materialize carry bit.
+
+let Defs = [EFLAGS], isCodeGenOnly = 1 in {
+def SETB_C8r : I<0x18, MRMInitReg, (outs GR8:$dst), (ins),
+ "sbb{b}\t$dst, $dst",
+ [(set GR8:$dst, (X86setcc_c X86_COND_B, EFLAGS))]>;
+def SETB_C16r : I<0x19, MRMInitReg, (outs GR16:$dst), (ins),
+ "sbb{w}\t$dst, $dst",
+ [(set GR16:$dst, (zext (X86setcc_c X86_COND_B, EFLAGS)))]>,
+ OpSize;
+def SETB_C32r : I<0x19, MRMInitReg, (outs GR32:$dst), (ins),
+ "sbb{l}\t$dst, $dst",
+ [(set GR32:$dst, (zext (X86setcc_c X86_COND_B, EFLAGS)))]>;
+} // isCodeGenOnly
+
def SETEr : I<0x94, MRM0r,
(outs GR8 :$dst), (ins),
"sete\t$dst",
@@ -4169,6 +4185,12 @@
GR16:$src2, (i8 imm:$amt2)), addr:$dst),
(SHLD16mri8 addr:$dst, GR16:$src2, (i8 imm:$amt1))>;
+// (anyext (setcc_carry)) -> (zext (setcc_carry))
+def : Pat<(i16 (anyext (X86setcc_c X86_COND_B, EFLAGS))),
+ (SETB_C16r)>;
+def : Pat<(i32 (anyext (X86setcc_c X86_COND_B, EFLAGS))),
+ (SETB_C32r)>;
+
//===----------------------------------------------------------------------===//
// EFLAGS-defining Patterns
//===----------------------------------------------------------------------===//