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Teach X86 backend to create BMI2 BZHI instructions from (and X, (add (shl 1, Y), -1)). Fixes PR17038. 

llvm-svn: 189653
This commit is contained in:
Craig Topper 2013-08-30 06:52:21 +00:00
parent be8d7ba93a
commit 0bccad2d43
4 changed files with 106 additions and 18 deletions
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68
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -13473,6 +13473,7 @@ const char *X86TargetLowering::getTargetNodeName(unsigned Opcode) const {
case X86ISD::BLSI: return "X86ISD::BLSI";
case X86ISD::BLSMSK: return "X86ISD::BLSMSK";
case X86ISD::BLSR: return "X86ISD::BLSR";
case X86ISD::BZHI: return "X86ISD::BZHI";
case X86ISD::MUL_IMM: return "X86ISD::MUL_IMM";
case X86ISD::PTEST: return "X86ISD::PTEST";
case X86ISD::TESTP: return "X86ISD::TESTP";
@ -17279,33 +17280,64 @@ static SDValue PerformAndCombine(SDNode *N, SelectionDAG &DAG,
if (R.getNode())
return R;
// Create BLSI, and BLSR instructions
// Create BLSI, BLSR, and BZHI instructions
// BLSI is X & (-X)
// BLSR is X & (X-1)
if (Subtarget->hasBMI() && (VT == MVT::i32 || VT == MVT::i64)) {
// BZHI is X & ((1 << Y) - 1)
if (VT == MVT::i32 || VT == MVT::i64) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDLoc DL(N);
// Check LHS for neg
if (N0.getOpcode() == ISD::SUB && N0.getOperand(1) == N1 &&
isZero(N0.getOperand(0)))
return DAG.getNode(X86ISD::BLSI, DL, VT, N1);
if (Subtarget->hasBMI()) {
// Check LHS for neg
if (N0.getOpcode() == ISD::SUB && N0.getOperand(1) == N1 &&
isZero(N0.getOperand(0)))
return DAG.getNode(X86ISD::BLSI, DL, VT, N1);
// Check RHS for neg
if (N1.getOpcode() == ISD::SUB && N1.getOperand(1) == N0 &&
isZero(N1.getOperand(0)))
return DAG.getNode(X86ISD::BLSI, DL, VT, N0);
// Check RHS for neg
if (N1.getOpcode() == ISD::SUB && N1.getOperand(1) == N0 &&
isZero(N1.getOperand(0)))
return DAG.getNode(X86ISD::BLSI, DL, VT, N0);
// Check LHS for X-1
if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N1 &&
isAllOnes(N0.getOperand(1)))
return DAG.getNode(X86ISD::BLSR, DL, VT, N1);
// Check LHS for X-1
if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N1 &&
isAllOnes(N0.getOperand(1)))
return DAG.getNode(X86ISD::BLSR, DL, VT, N1);
// Check RHS for X-1
if (N1.getOpcode() == ISD::ADD && N1.getOperand(0) == N0 &&
isAllOnes(N1.getOperand(1)))
return DAG.getNode(X86ISD::BLSR, DL, VT, N0);
// Check RHS for X-1
if (N1.getOpcode() == ISD::ADD && N1.getOperand(0) == N0 &&
isAllOnes(N1.getOperand(1)))
return DAG.getNode(X86ISD::BLSR, DL, VT, N0);
}
if (Subtarget->hasBMI2()) {
// Check for (and (add (shl 1, Y), -1), X)
if (N0.getOpcode() == ISD::ADD && isAllOnes(N0.getOperand(1))) {
SDValue N00 = N0.getOperand(0);
if (N00.getOpcode() == ISD::SHL) {
SDValue N001 = N00.getOperand(1);
assert(N001.getValueType() == MVT::i8 && "unexpected type");
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N00.getOperand(0));
if (C && C->getZExtValue() == 1)
return DAG.getNode(X86ISD::BZHI, DL, VT, N1,
DAG.getNode(ISD::ZERO_EXTEND, DL, VT, N001));
}
}
// Check for (and X, (add (shl 1, Y), -1))
if (N1.getOpcode() == ISD::ADD && isAllOnes(N1.getOperand(1))) {
SDValue N10 = N1.getOperand(0);
if (N10.getOpcode() == ISD::SHL) {
SDValue N101 = N10.getOperand(1);
assert(N101.getValueType() == MVT::i8 && "unexpected type");
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N10.getOperand(0));
if (C && C->getZExtValue() == 1)
return DAG.getNode(X86ISD::BZHI, DL, VT, N0,
DAG.getNode(ISD::ZERO_EXTEND, DL, VT, N101));
}
}
}
return SDValue();
}

1
llvm/lib/Target/X86/X86ISelLowering.h
View File

@ -295,6 +295,7 @@ namespace llvm {
BLSI, // BLSI - Extract lowest set isolated bit
BLSMSK, // BLSMSK - Get mask up to lowest set bit
BLSR, // BLSR - Reset lowest set bit
BZHI, // BZHI - Zero high bits
UMUL, // LOW, HI, FLAGS = umul LHS, RHS

10
llvm/lib/Target/X86/X86InstrInfo.td
View File

@ -253,6 +253,7 @@ def X86andn_flag : SDNode<"X86ISD::ANDN", SDTBinaryArithWithFlags>;
def X86blsi : SDNode<"X86ISD::BLSI", SDTIntUnaryOp>;
def X86blsmsk : SDNode<"X86ISD::BLSMSK", SDTIntUnaryOp>;
def X86blsr : SDNode<"X86ISD::BLSR", SDTIntUnaryOp>;
def X86bzhi : SDNode<"X86ISD::BZHI", SDTIntBinOp>;
def X86mul_imm : SDNode<"X86ISD::MUL_IMM", SDTIntBinOp>;
@ -1856,6 +1857,15 @@ let Predicates = [HasBMI2], Defs = [EFLAGS] in {
int_x86_bmi_bzhi_64, loadi64>, VEX_W;
}
def : Pat<(X86bzhi GR32:$src1, GR32:$src2),
(BZHI32rr GR32:$src1, GR32:$src2)>;
def : Pat<(X86bzhi (loadi32 addr:$src1), GR32:$src2),
(BZHI32rm addr:$src1, GR32:$src2)>;
def : Pat<(X86bzhi GR64:$src1, GR64:$src2),
(BZHI64rr GR64:$src1, GR64:$src2)>;
def : Pat<(X86bzhi (loadi64 addr:$src1), GR64:$src2),
(BZHI64rm addr:$src1, GR64:$src2)>;
multiclass bmi_pdep_pext<string mnemonic, RegisterClass RC,
X86MemOperand x86memop, Intrinsic Int,
PatFrag ld_frag> {

45
llvm/test/CodeGen/X86/bmi.ll
View File

@ -146,6 +146,51 @@ define i64 @bzhi64(i64 %x, i64 %y) nounwind readnone {
declare i64 @llvm.x86.bmi.bzhi.64(i64, i64) nounwind readnone
define i32 @bzhi32b(i32 %x, i8 zeroext %index) #0 {
entry:
%conv = zext i8 %index to i32
%shl = shl i32 1, %conv
%sub = add nsw i32 %shl, -1
%and = and i32 %sub, %x
ret i32 %and
; CHECK-LABEL: bzhi32b:
; CHECK: bzhil
}
define i32 @bzhi32b_load(i32* %w, i8 zeroext %index) #0 {
entry:
%x = load i32* %w
%conv = zext i8 %index to i32
%shl = shl i32 1, %conv
%sub = add nsw i32 %shl, -1
%and = and i32 %sub, %x
ret i32 %and
; CHECK-LABEL: bzhi32b_load:
; CHECK: bzhil {{.*}}, ({{.*}}), {{.*}}
}
define i32 @bzhi32c(i32 %x, i8 zeroext %index) #0 {
entry:
%conv = zext i8 %index to i32
%shl = shl i32 1, %conv
%sub = add nsw i32 %shl, -1
%and = and i32 %x, %sub
ret i32 %and
; CHECK-LABEL: bzhi32c:
; CHECK: bzhil
}
define i64 @bzhi64b(i64 %x, i8 zeroext %index) #0 {
entry:
%conv = zext i8 %index to i64
%shl = shl i64 1, %conv
%sub = add nsw i64 %shl, -1
%and = and i64 %x, %sub
ret i64 %and
; CHECK-LABEL: bzhi64b:
; CHECK: bzhiq
}
define i32 @blsi32(i32 %x) nounwind readnone {
%tmp = sub i32 0, %x
%tmp2 = and i32 %x, %tmp