[mips] Preparatory work for a generic scheduler

Extend instruction definitions from nearly all ISAs to include
appropriate instruction itineraries. Change MIPS16s gp prologue
generation to use real instructions instead of using a pseudo
instruction.

Reviewers: dsanders, vkalintiris

Differential Review: https://reviews.llvm.org/D23548

llvm-svn: 279623
diff --git a/llvm/test/CodeGen/Mips/llvm-ir/sdiv.ll b/llvm/test/CodeGen/Mips/llvm-ir/sdiv.ll
index 2d2b8ff..0bbdae8 100644
--- a/llvm/test/CodeGen/Mips/llvm-ir/sdiv.ll
+++ b/llvm/test/CodeGen/Mips/llvm-ir/sdiv.ll
@@ -188,7 +188,7 @@
   ; GP64-NOT-R6:  ld      $25, %call16(__divti3)($gp)
   ; 64R6:         ld      $25, %call16(__divti3)($gp)
 
-  ; MM32:         lw      $25, %call16(__divti3)($2)
+  ; MM32:         lw      $25, %call16(__divti3)($16)
 
   ; MM64:         ld      $25, %call16(__divti3)($2)