[dev.ssa] cmd/compile: clean up tuple types and selects

Make tuple types and their SelectX ops fully generic.
These ops no longer need to be lowered.
Regalloc understands them and their tuple-generating arguments.
We can now have opcodes returning arbitrary pairs of results.
(And it would be easy to move to >2 results if needed.)

Update arm implementation to the new standard.
Implement just enough in 386 port to do 64-bit add.

Change-Id: I370ed5aacce219c82e1954c61d1f63af76c16f79
Reviewed-on: https://go-review.googlesource.com/24976
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/location.go b/src/cmd/compile/internal/ssa/location.go
index 85f525565b..fc3a19ca35 100644
--- a/src/cmd/compile/internal/ssa/location.go
+++ b/src/cmd/compile/internal/ssa/location.go
@@ -36,3 +36,16 @@ func (s LocalSlot) Name() string {
 	}
 	return fmt.Sprintf("%s+%d[%s]", s.N, s.Off, s.Type)
 }
+
+type LocPair [2]Location
+
+func (t LocPair) Name() string {
+	n0, n1 := "nil", "nil"
+	if t[0] != nil {
+		n0 = t[0].Name()
+	}
+	if t[1] != nil {
+		n1 = t[1].Name()
+	}
+	return fmt.Sprintf("<%s,%s>", n0, n1)
+}