cmd/compile: soup up isSamePtr

This increases the number of matches in make.bash
from 853 to 984.

Change-Id: I12697697a50ecd86d49698200144a4c80dd3e5a4
Reviewed-on: https://go-review.googlesource.com/20274
Reviewed-by: Todd Neal <todd@tneal.org>

diff --git a/src/cmd/compile/internal/ssa/rewrite.go b/src/cmd/compile/internal/ssa/rewrite.go
index 86f3c2010e1131d65eb2fd47c0f9e3497bcd512d..356b375657df35160c883b993ce51d24e7a0fbde 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewrite.go
+++ b/src/cmd/compile/internal/ssa/rewrite.go
@@ -207,11 +207,20 @@ func isSamePtr(p1, p2 *Value) bool {
        if p1 == p2 {
                return true
        }
-       // Aux isn't used  in OffPtr, and AuxInt isn't currently used in
-       // Addr, but this still works as the values will be null/0
-       return (p1.Op == OpOffPtr || p1.Op == OpAddr) && p1.Op == p2.Op &&
-               p1.Aux == p2.Aux && p1.AuxInt == p2.AuxInt &&
-               p1.Args[0] == p2.Args[0]
+       if p1.Op != p2.Op {
+               return false
+       }
+       switch p1.Op {
+       case OpOffPtr:
+               return p1.AuxInt == p2.AuxInt && isSamePtr(p1.Args[0], p2.Args[0])
+       case OpAddr:
+               // OpAddr's 0th arg is either OpSP or OpSB, which means that it is uniquely identified by its Op.
+               // Checking for value equality only works after [z]cse has run.
+               return p1.Aux == p2.Aux && p1.Args[0].Op == p2.Args[0].Op
+       case OpAddPtr:
+               return p1.Args[1] == p2.Args[1] && isSamePtr(p1.Args[0], p2.Args[0])
+       }
+       return false
 }
 
 // DUFFZERO consists of repeated blocks of 4 MOVUPSs + ADD,