Displaying 2 results from an estimated 2 matches for "m_combineand".
2018 Dec 18
2
should we do this time-consuming transform in InstCombine?
...ing is performed/allowed.
This should match that *specific* pattern (other than verifying the
correct equal binop types), although i have not tested it:
ICmpInst::Predicate Pred;
Value *A, *B, *Mul, *Sub, *Mul2;
if (match(&SI,
m_Select(m_ICmp(Pred,
m_CombineAnd(m_BinOp(m_Value(A), m_Value(B)),
m_Value(Mul)),
m_AllOnes()),
m_Deferred(Mul),
m_CombineAnd(
m_c_BinOp(m_CombineAnd(m_Sub(m_Zero(), m_Deferred
(A)),...
2018 Dec 18
2
should we do this time-consuming transform in InstCombine?
Hi,
There is an opportunity in instCombine for following instruction pattern:
%mul = mul nsw i32 %b, %a
%cmp = icmp sgt i32 %mul, -1
%sub = sub i32 0, %a
%mul2 = mul nsw i32 %sub, %b
%cond = select i1 %cmp, i32 %mul, i32 %mul2
Source code for above pattern:
return (a*b) >=0 ? (a*b) : -a*b;
Currently, llvm(-O3) can not recognize this as abs(a*b).
I initially think we could do this in