cmd/compile: invalidate CFG when fuseIf triggers

The compiler appears to have a latent bug:
fusePlain calls invalidateCFG when it changes block structure,
but fuseIf does not.

Fix this by hoisting the call to invalidateCFG to the top level.

Change-Id: Ic960fb3ac963b15b4a225aad84863d58efa954e6
Reviewed-on: https://go-review.googlesource.com/c/go/+/177198
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/compile/internal/ssa/fuse.go b/src/cmd/compile/internal/ssa/fuse.go
index c451904124bf40b76412d8e6b2168e981a052f9b..73532ee6e50907eb5c1f5d7a7b1f570d1cc7c82a 100644 (file)
--- a/src/cmd/compile/internal/ssa/fuse.go
+++ b/src/cmd/compile/internal/ssa/fuse.go
@@ -36,6 +36,9 @@ func fuse(f *Func, typ fuseType) {
                                changed = fuseBlockPlain(b) || changed
                        }
                }
+               if changed {
+                       f.invalidateCFG()
+               }
        }
 }
 
@@ -207,7 +210,6 @@ func fuseBlockPlain(b *Block) bool {
        if f.Entry == b {
                f.Entry = c
        }
-       f.invalidateCFG()
 
        // trash b, just in case
        b.Kind = BlockInvalid