diff options
| author | Manman Ren <mren@apple.com> | 2012-04-30 22:51:25 +0000 |
|---|---|---|
| committer | Manman Ren <mren@apple.com> | 2012-04-30 22:51:25 +0000 |
| commit | 16a76519a5aa0e3a351cfde8e7236119ffd8b7fb (patch) | |
| tree | 97a13cf302560765c6b11772e89492122789fbc0 | |
| parent | 7a3afa91ad8f68428373948fc16375e99bff3c6f (diff) | |
X86: optimization for -(x != 0)
This patch will optimize -(x != 0) on X86
FROM
cmpl $0x01,%edi
sbbl %eax,%eax
notl %eax
TO
negl %edi
sbbl %eax %eax
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155853 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Target/X86/X86ISelLowering.cpp | 16 | ||||
| -rw-r--r-- | test/CodeGen/X86/select.ll | 21 |
2 files changed, 37 insertions, 0 deletions
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index 83c357d708..660a1bd0bd 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -8589,6 +8589,22 @@ SDValue X86TargetLowering::LowerSELECT(SDValue Op, SelectionDAG &DAG) const { SDValue Y = isAllOnes(Op2) ? Op1 : Op2; SDValue CmpOp0 = Cmp.getOperand(0); + // further optimization for special cases + // (select (x != 0), -1, 0) -> neg & sbb + // (select (x == 0), 0, -1) -> neg & sbb + if (ConstantSDNode *YC = dyn_cast<ConstantSDNode>(Y)) + if (YC->isNullValue() && + (isAllOnes(Op1) == (CondCode == X86::COND_NE))) { + SDVTList VTs = DAG.getVTList(CmpOp0.getValueType(), MVT::i32); + SDValue Neg = DAG.getNode(ISD::SUB, DL, VTs, + DAG.getConstant(0, CmpOp0.getValueType()), + CmpOp0); + SDValue Res = DAG.getNode(X86ISD::SETCC_CARRY, DL, Op.getValueType(), + DAG.getConstant(X86::COND_B, MVT::i8), + SDValue(Neg.getNode(), 1)); + return Res; + } + Cmp = DAG.getNode(X86ISD::CMP, DL, MVT::i32, CmpOp0, DAG.getConstant(1, CmpOp0.getValueType())); Cmp = ConvertCmpIfNecessary(Cmp, DAG); diff --git a/test/CodeGen/X86/select.ll b/test/CodeGen/X86/select.ll index 9adf4f9c05..5730f618e4 100644 --- a/test/CodeGen/X86/select.ll +++ b/test/CodeGen/X86/select.ll @@ -218,3 +218,24 @@ define i32 @test14(i32 %a, i32 %b) nounwind { ; CHECK-NEXT: ret } +; rdar://10961709 +define i32 @test15(i32 %x) nounwind { +entry: + %cmp = icmp ne i32 %x, 0 + %sub = sext i1 %cmp to i32 + ret i32 %sub +; CHECK: test15: +; CHECK: negl +; CHECK: sbbl +} + +define i32 @test16(i32 %x) nounwind { +entry: + %c = icmp eq i32 %x, 0 + %d = select i1 %c, i32 0, i32 -1 + ret i32 %d +; CHECK: test16: +; CHECK: negl +; CHECK: sbbl +} + |