[InstCombine] add folds for minnum(-a, -b) --> -maxnum(a, b)
This is similar to what we do for integer min/max with 'not'
ops (rL321882).
This should fix:
https://bugs.llvm.org/show_bug.cgi?id=37404
https://bugs.llvm.org/show_bug.cgi?id=37405
llvm-svn: 332031
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index c0c6a0d..d36380e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1952,8 +1952,24 @@
II->setArgOperand(1, Arg0);
return II;
}
+
+ // FIXME: Simplifications should be in instsimplify.
if (Value *V = simplifyMinnumMaxnum(*II))
return replaceInstUsesWith(*II, V);
+
+ Value *X, *Y;
+ if (match(Arg0, m_FNeg(m_Value(X))) && match(Arg1, m_FNeg(m_Value(Y))) &&
+ (Arg0->hasOneUse() || Arg1->hasOneUse())) {
+ // If both operands are negated, invert the call and negate the result:
+ // minnum(-X, -Y) --> -(maxnum(X, Y))
+ // maxnum(-X, -Y) --> -(minnum(X, Y))
+ Intrinsic::ID NewIID = II->getIntrinsicID() == Intrinsic::maxnum ?
+ Intrinsic::minnum : Intrinsic::maxnum;
+ Value *NewCall = Builder.CreateIntrinsic(NewIID, { X, Y }, II);
+ Instruction *FNeg = BinaryOperator::CreateFNeg(NewCall);
+ FNeg->copyIRFlags(II);
+ return FNeg;
+ }
break;
}
case Intrinsic::fmuladd: {