Enhance boolean simplification to handle 16-/64-bit RDRAND
- RDRAND always clears the destination value when a random value is not
available (i.e. CF == 0). This value is truncated or zero-extended as
the false boolean value to be returned. Boolean simplification needs
to skip this 'zext' or 'trunc' node.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178312 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 709e9e8..e0f87c0 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -15821,8 +15821,9 @@
// Quit if the constant is neither 0 or 1.
return SDValue();
- // Skip 'zext' node.
- if (SetCC.getOpcode() == ISD::ZERO_EXTEND)
+ // Skip 'zext' or 'trunc' node.
+ if (SetCC.getOpcode() == ISD::ZERO_EXTEND ||
+ SetCC.getOpcode() == ISD::TRUNCATE)
SetCC = SetCC.getOperand(0);
switch (SetCC.getOpcode()) {
@@ -15841,9 +15842,13 @@
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)
+ // Skip 'zext' or 'trunc' node.
+ if (Op.getOpcode() == ISD::ZERO_EXTEND ||
+ Op.getOpcode() == ISD::TRUNCATE)
+ Op = Op.getOperand(0);
+ // A special case for rdrand, where 0 is set if false cond is found.
+ if (Op.getOpcode() != X86ISD::RDRAND || Op.getResNo() != 0)
return SDValue();
}
// Quit if false value is not the constant 0 or 1.