[mips] Split Instruction.Predicates into smaller lists and re-join them with !listconcat

Summary:
The overall idea is to chop the Predicates list into subsets that are
usually overridden independently. This allows subclasses to partially
override the predicates of their superclasses without having to re-add all
the existing predicates.

This patch starts the process by moving HasStdEnc into a new
EncodingPredicates list and almost everything else into
AdditionalPredicates.

It has revealed a couple likely bugs where 'let Predicates' has removed
the HasStdEnc predicate.

No functional change (confirmed by diffing tablegen-erated files).

Depends on D3549, D3506

Reviewers: vmedic

Differential Revision: http://reviews.llvm.org/D3550

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208184 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/Target/Mips/Mips.td b/lib/Target/Mips/Mips.td
index f0ada2b63fe..30793e5fb77 100644
--- a/lib/Target/Mips/Mips.td
+++ b/lib/Target/Mips/Mips.td
@@ -15,6 +15,24 @@
 
 include "llvm/Target/Target.td"
 
+// The overall idea of the PredicateControl class is to chop the Predicates list
+// into subsets that are usually overridden independently. This allows
+// subclasses to partially override the predicates of their superclasses without
+// having to re-add all the existing predicates.
+class PredicateControl {
+  // Predicates for the encoding scheme in use such as HasStdEnc
+  list<Predicate> EncodingPredicates = [];
+  // Predicates for anything else
+  list<Predicate> AdditionalPredicates = [];
+  list<Predicate> Predicates = !listconcat(EncodingPredicates,
+                                           AdditionalPredicates);
+}
+
+// Like Requires<> but for the AdditionalPredicates list
+class AdditionalRequires<list<Predicate> preds> {
+  list<Predicate> AdditionalPredicates = preds;
+}
+
 //===----------------------------------------------------------------------===//
 // Register File, Calling Conv, Instruction Descriptions
 //===----------------------------------------------------------------------===//