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Properly check if a CMPZ node is in fact comparing against zero

This was left implicit and never ever checked, which means we could have a CMPZ against some non-zero value and we were carrying on with BFI conversion regardless.

Caught by Oliver Stannard using csmith; regression test added.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253195 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
James Molloy 2015-11-16 10:49:25 +00:00
parent 168146e84b
commit 61639fb856
2 changed files with 17 additions and 0 deletions
lib/Target/ARM
test/CodeGen/ARM

View File

@ -10398,6 +10398,12 @@ SDValue ARMTargetLowering::PerformCMOVToBFICombine(SDNode *CMOV, SelectionDAG &D
auto CC = CCNode->getAPIntValue().getLimitedValue();
SDValue CmpZ = CMOV->getOperand(4);
// The compare must be against zero.
SDValue Zero = CmpZ->getOperand(1);
if (!isa<ConstantSDNode>(Zero.getNode()) ||
!cast<ConstantSDNode>(Zero.getNode())->isNullValue())
return SDValue();
assert(CmpZ->getOpcode() == ARMISD::CMPZ);
SDValue And = CmpZ->getOperand(0);
if (And->getOpcode() != ISD::AND)

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@ -158,3 +158,14 @@ define i32 @f12(i32 %x, i32 %y) {
%sel = select i1 %cmp, i32 %y2, i32 %or
ret i32 %sel
}
define i32 @f13(i32 %x, i32 %y) {
; CHECK-LABEL: f13:
; CHECK-NOT: bfi
%y2 = and i32 %y, 4294967040 ; 0xFFFFFF00
%and = and i32 %x, 4
%or = or i32 %y2, 16
%cmp = icmp eq i32 %and, 42 ; Not comparing against zero!
%sel = select i1 %cmp, i32 %y2, i32 %or
ret i32 %sel
}