Use ARM/t2PseudoInst class from ARM/Thumb2 special adds/subs patterns.

Clean up the patterns, fix comments, and avoid confusing both tools
and coders. Note that the special adds/subs SelectionDAG nodes no
longer have the dummy cc_out operand.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142397 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/include/llvm/Target/Target.td b/include/llvm/Target/Target.td
index 6e28f79694..9714172aa4 100644
--- a/include/llvm/Target/Target.td
+++ b/include/llvm/Target/Target.td
@@ -356,6 +356,15 @@ class Instruction {
   // associated with them. Once we've migrated all of them over to true
   // pseudo-instructions that are lowered to real instructions prior to
   // the printer/emitter, we can remove this attribute and just use isPseudo.
+  //
+  // The intended use is:
+  // isPseudo: Does not have encoding information and should be expanded,
+  //   at the latest, during lowering to MCInst.
+  //
+  // isCodeGenOnly: Does have encoding information and can go through to the
+  //   CodeEmitter unchanged, but duplicates a canonical instruction
+  //   definition's encoding and should be ignored when constructing the
+  //   assembler match tables.
   bit isCodeGenOnly = 0;
 
   // Is this instruction a pseudo instruction for use by the assembler parser.