I noticed this problem as part of the ongoing attempt to canonicalize min/max ops in IR.
The debug output shows nodes like this:
t4: i32 = xor t2, Constant:i32<-1>
t21: i8 = setcc t4, Constant:i32<0>, setlt:ch
t14: i32 = select t21, t4, Constant:i32<-1>
And because the select is holding onto the t4 (xor) node while EmitTest creates a new
x86-specific xor node, the lowering results in:
t4: i32 = xor t2, Constant:i32<-1>
t25: i32,i32 = X86ISD::XOR t2, Constant:i32<-1>
t28: i32,glue = X86ISD::CMOV Constant:i32<-1>, t4, Constant:i8<15>, t25:1
Differential Revision: https://reviews.llvm.org/D28374
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291392
91177308-0d34-0410-b5e6-
96231b3b80d8
return DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, VT, newSelect, zeroConst);
}
- if (Cond.getOpcode() == ISD::SETCC)
- if (SDValue NewCond = LowerSETCC(Cond, DAG))
+ if (Cond.getOpcode() == ISD::SETCC) {
+ if (SDValue NewCond = LowerSETCC(Cond, DAG)) {
Cond = NewCond;
+ // If the condition was updated, it's possible that the operands of the
+ // select were also updated (for example, EmitTest has a RAUW). Refresh
+ // the local references to the select operands in case they got stale.
+ Op1 = Op.getOperand(1);
+ Op2 = Op.getOperand(2);
+ }
+ }
// (select (x == 0), -1, y) -> (sign_bit (x - 1)) | y
// (select (x == 0), y, -1) -> ~(sign_bit (x - 1)) | y
ret i8 %d
}
-; FIXME: The 'not' is redundant.
-
define i32 @smin(i32 %x) {
; CHECK-LABEL: smin:
; CHECK: ## BB#0:
-; CHECK-NEXT: movl %edi, %ecx
-; CHECK-NEXT: notl %ecx
; CHECK-NEXT: xorl $-1, %edi
; CHECK-NEXT: movl $-1, %eax
-; CHECK-NEXT: cmovsl %ecx, %eax
+; CHECK-NEXT: cmovsl %edi, %eax
; CHECK-NEXT: retq
%not_x = xor i32 %x, -1
%1 = icmp slt i32 %not_x, -1