There was a logic hole in D42739 / rL324014 because we're not accounting for select and phi
instructions that might have repeated operands. This is likely a source of an infinite loop.
I haven't manufactured a test case to prove that, but it should be safe to speculatively limit
this transform to binops while we try to create that test.
llvm-svn: 324252
if (!isa<Instruction>(V))
return true;
// We can't extend or shrink something that has multiple uses -- unless those
- // multiple uses are all in the same instruction -- doing so would require
- // duplicating the instruction which isn't profitable.
- if (!V->hasOneUse())
+ // multiple uses are all in the same binop instruction -- doing so would
+ // require duplicating the instruction which isn't profitable.
+ if (!V->hasOneUse()) {
+ if (!match(V->user_back(), m_BinOp()))
+ return true;
if (any_of(V->users(), [&](User *U) { return U != V->user_back(); }))
return true;
-
+ }
return false;
}