On Feb 18, 2008, at 9:55 AM, Dan Gohman wrote: > Don't mark scalar integer multiplication as Expand on x86, since x86 > has plain one-result scalar integer multiplication instructions. > This avoids expanding such instructions into MUL_LOHI sequences that > must be special-cased at isel time, and avoids the problem with that > code that provented memory operands from being folded. > > This fixes PR1874, addressesing the most common case. The uncommon > cases of optimizing multiply-high operations will require work > in DAGCombiner.
Very nice! > + // 8, 16, and 32-bit plain multiply are legal. And 64-bit multiply > + // is also legal on x86-64. > + if (!Subtarget->is64Bit()) > + setOperationAction(ISD::MUL , MVT::i64 , Expand); Are you sure you need this? if !is64Bit(), i64 won't be legal, so the multiply will be expanded unconditionally. -Chris _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
