Fix comment so it doesn't include comments which are irrelevant to the x86
backend. Add a FIXME noting what can be fixed here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105342 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index a322ad2..1d59978 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -981,16 +981,12 @@
setOperationAction(ISD::USUBO, MVT::i32, Custom);
setOperationAction(ISD::SMULO, MVT::i32, Custom);
- // Don't try to custom-lower 64-bit add-with-overflow and friends
- // on x86-32; the x86 backend currently doesn't know how to handle them.
+ // Only custom-lower 64-bit SADDO and friends on 64-bit because we don't
+ // handle type legalization for these operations here.
//
- // This doesn't really fix anything because LegalizeTypes doesn't know
- // how to handle them either. We do get a better error message, though.
- //
- // This may not be hard to implement though.
- // In fact you could even cheat, and turn the 64 bit add-with-overflow
- // into a 65 bit add, with the top bit being used to compute the overflow
- // flag. That should then all get expanded out automagically.
+ // FIXME: We really should do custom legalization for addition and
+ // subtraction on x86-32 once PR3203 is fixed. We really can't do much better
+ // than generic legalization for 64-bit multiplication-with-overflow, though.
if (Subtarget->is64Bit()) {
setOperationAction(ISD::SADDO, MVT::i64, Custom);
setOperationAction(ISD::UADDO, MVT::i64, Custom);