return GlobalSwapBenefits > 0;
}
-// Helper function to check whether Op represents a lshr/ashr exact
-// instruction. For example:
-// (icmp (ashr exact const2, A), const1) -> icmp A, Log2(const2/const1)
-// Here if Op represents -> (ashr exact const2, A), and CI represents
-// const1, we compute Quotient as const2/const1.
-
-static bool checkShrExact(Value *Op, APInt &Quotient, const ConstantInt *CI,
- Value *&A) {
-
- ConstantInt *CI2;
- if (match(Op, m_AShr(m_ConstantInt(CI2), m_Value(A))) &&
- (cast<BinaryOperator>(Op)->isExact())) {
- Quotient = CI2->getValue().sdiv(CI->getValue());
- return true;
- }
-
- // Handle the case for lhsr.
- if (match(Op, m_LShr(m_ConstantInt(CI2), m_Value(A))) &&
- (cast<BinaryOperator>(Op)->isExact())) {
- Quotient = CI2->getValue().udiv(CI->getValue());
- return true;
- }
-
- return false;
-}
-
Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
bool Changed = false;
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
return new ICmpInst(I.getPredicate(), A, B);
}
- // PR19753:
- // (icmp (ashr exact const2, A), const1) -> icmp A, Log2(const2/const1)
- // Cases where const1 doesn't divide const2 exactly or Quotient is not
- // exact of log2 are handled by SimplifyICmpInst call above where we
- // return false. Similar for lshr.
- {
- APInt Quotient;
- if (checkShrExact(Op0, Quotient, CI, A)) {
- unsigned shift = Quotient.logBase2();
- return new ICmpInst(I.getPredicate(), A,
- ConstantInt::get(A->getType(), shift));
- }
- }
-
// If we have an icmp le or icmp ge instruction, turn it into the
// appropriate icmp lt or icmp gt instruction. This allows us to rely on
// them being folded in the code below. The SimplifyICmpInst code has
%2 = icmp slt i32 %1, -10
ret i1 %2
}
-
-; CHECK-LABEL: @exact_ashr_eq_false
-; CHECK-NEXT: icmp eq i32 %a, 1
-define i1 @exact_ashr_eq_false(i32 %a) {
- %shr = ashr exact i32 -30, %a
- %cmp = icmp eq i32 %shr, -15
- ret i1 %cmp
-}
-
-; CHECK-LABEL: @exact_lhsr
-; CHECK-NEXT: icmp eq i32 %a, 3
-define i1 @exact_lhsr(i32 %a) {
- %shr = lshr exact i32 80, %a
- %cmp = icmp eq i32 %shr, 10
- ret i1 %cmp
-}