cmd/compile: use optimized slice zeroing in deadcode

Minor cleanup. Passes toolstash-check.

Change-Id: I97a027c4ca49ded593e9c7989e9e091ab9336fa3
Reviewed-on: https://go-review.googlesource.com/c/go/+/227318
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

diff --git a/src/cmd/compile/internal/ssa/deadcode.go b/src/cmd/compile/internal/ssa/deadcode.go
index b79ec7c2f68c6e36ab45e1a3c9724fc305a6102b..395c1617e5748ebdc7e8c6068bc8c74956a0c9f4 100644 (file)
--- a/src/cmd/compile/internal/ssa/deadcode.go
+++ b/src/cmd/compile/internal/ssa/deadcode.go
@@ -242,8 +242,9 @@ func deadcode(f *Func) {
                        f.NamedValues[name] = values[:j]
                }
        }
-       for k := len(f.Names) - 1; k >= i; k-- {
-               f.Names[k] = LocalSlot{}
+       clearNames := f.Names[i:]
+       for j := range clearNames {
+               clearNames[j] = LocalSlot{}
        }
        f.Names = f.Names[:i]
 
@@ -311,8 +312,9 @@ func deadcode(f *Func) {
                        i++
                }
        }
-       for j := i; j < len(f.WBLoads); j++ {
-               f.WBLoads[j] = nil
+       clearWBLoads := f.WBLoads[i:]
+       for j := range clearWBLoads {
+               clearWBLoads[j] = nil
        }
        f.WBLoads = f.WBLoads[:i]