[PATCH] D13417: [MachineCombiner] make slack optional in critical path cost calculation (PR25016)

[Gerolf Hoflehner via llvm-commits]

Gerolf added a comment.

Now that you check for schedule depth for reassociations do you still need to check for shorter length? If so, for which pattern? I think we should get away with checks for depth (MustReduceDepth) and just leave the default (don't prolong critical path) for the muladd etc patterns.


================
Comment at: lib/CodeGen/MachineCombiner.cpp:329
@@ -321,1 +328,3 @@
 
+/// For some patterns, we want to use a more conservative cost metric when
+/// when evaluating if a transform is beneficial. These patterns require that
----------------
could we have that function return eg. an enum CombinerObjective that return MustReduceDepth or Default? Then improvesCriticalPathLength only needs one parameter of that type.


http://reviews.llvm.org/D13417