[PATCH] D29711: [globalisel] Sort RuleMatchers by priority.

[Ahmed Bougacha via Phabricator via llvm-commits]

ab added inline comments.


================
Comment at: utils/TableGen/GlobalISelEmitter.cpp:224-230
+    // Wider types should have priority over narrower types within the same
+    // family but the order of the families doesn't matter. So s64 is more
+    // important than s32 and f64 is more important than f32 but s64 and f64 are
+    // unordered.
+    // FIXME: Don't do a lexical comparison of the type name. Check the size
+    //        instead. This only works for the cases we emit so far and is only
+    //        done this way because we can't delve into LLT's yet.
----------------
dsanders wrote:
> ab wrote:
> > Huh, how can this be a problem?
> It works fine for s32 and s64 since "s32" < "s64" but the overall ordering is wrong when the number of digits vary:
>   "s128" < "s16" < "s32" < "s64" < "s8"
> Once I've dealt with the LLT layering issue we'll be able to do a numeric comparison for the size such that the order is:
>   s8 < s16 < s32 < s64 < s128
Sorry; I'm asking why does the ordering matter in the first place?


https://reviews.llvm.org/D29711