Add boolean simplification support from CMOV
- If a boolean value is generated from CMOV and tested as boolean value,
simplify the use of test result by referencing the original condition.
RDRAND intrinisc is one of such cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163516 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 0ad74c9..b0dc5b7 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -14158,19 +14158,49 @@
if (SetCC.getOpcode() == ISD::ZERO_EXTEND)
SetCC = SetCC.getOperand(0);
- // Quit if not SETCC.
- // FIXME: So far we only handle the boolean value generated from SETCC. If
- // there is other ways to generate boolean values, we need handle them here
- // as well.
- if (SetCC.getOpcode() != X86ISD::SETCC)
- return SDValue();
+ switch (SetCC.getOpcode()) {
+ case X86ISD::SETCC:
+ // Set the condition code or opposite one if necessary.
+ CC = X86::CondCode(SetCC.getConstantOperandVal(0));
+ if (needOppositeCond)
+ CC = X86::GetOppositeBranchCondition(CC);
+ return SetCC.getOperand(1);
+ case X86ISD::CMOV: {
+ // Check whether false/true value has canonical one, i.e. 0 or 1.
+ ConstantSDNode *FVal = dyn_cast<ConstantSDNode>(SetCC.getOperand(0));
+ ConstantSDNode *TVal = dyn_cast<ConstantSDNode>(SetCC.getOperand(1));
+ // Quit if true value is not a constant.
+ if (!TVal)
+ return SDValue();
+ // Quit if false value is not a constant.
+ if (!FVal) {
+ // A special case for rdrand, where 0 is set if false cond is found.
+ SDValue Op = SetCC.getOperand(0);
+ if (Op.getOpcode() != X86ISD::RDRAND)
+ return SDValue();
+ }
+ // Quit if false value is not the constant 0 or 1.
+ bool FValIsFalse = true;
+ if (FVal && FVal->getZExtValue() != 0) {
+ if (FVal->getZExtValue() != 1)
+ return SDValue();
+ // If FVal is 1, opposite cond is needed.
+ needOppositeCond = !needOppositeCond;
+ FValIsFalse = false;
+ }
+ // Quit if TVal is not the constant opposite of FVal.
+ if (FValIsFalse && TVal->getZExtValue() != 1)
+ return SDValue();
+ if (!FValIsFalse && TVal->getZExtValue() != 0)
+ return SDValue();
+ CC = X86::CondCode(SetCC.getConstantOperandVal(2));
+ if (needOppositeCond)
+ CC = X86::GetOppositeBranchCondition(CC);
+ return SetCC.getOperand(3);
+ }
+ }
- // Set the condition code or opposite one if necessary.
- CC = X86::CondCode(SetCC.getConstantOperandVal(0));
- if (needOppositeCond)
- CC = X86::GetOppositeBranchCondition(CC);
-
- return SetCC.getOperand(1);
+ return SDValue();
}
/// checkFlaggedOrCombine - DAG combination on X86ISD::OR, i.e. with EFLAGS