[dev.ssa] cmd/compile: implement control flow handling

Add label and goto checks and improve test coverage.

Implement OSWITCH and OSELECT.

Implement OBREAK and OCONTINUE.

Allow generation of code in dead blocks.

Change-Id: Ibebb7c98b4b2344f46d38db7c9dce058c56beaac
Reviewed-on: https://go-review.googlesource.com/12445
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 27 insertions, 4 deletions

diff --git a/test/label1.go b/test/label1.go
index bc8fea6f6a..937b5cb900 100644
--- a/test/label1.go
+++ b/test/label1.go
@@ -31,11 +31,17 @@ L2:
 			break L2
 		}
 		if x == 1 {
-			continue L2 // ERROR "invalid continue label .*L2"
+			continue L2 // ERROR "invalid continue label .*L2|continue is not in a loop"
 		}
 		goto L2
 	}
 
+	for {
+		if x == 1 {
+			continue L2 // ERROR "invalid continue label .*L2"
+		}
+	}
+
 L3:
 	switch {
 	case x > 10:
@@ -43,7 +49,7 @@ L3:
 			break L3
 		}
 		if x == 12 {
-			continue L3 // ERROR "invalid continue label .*L3"
+			continue L3 // ERROR "invalid continue label .*L3|continue is not in a loop"
 		}
 		goto L3
 	}
@@ -54,7 +60,7 @@ L4:
 			break L4 // ERROR "invalid break label .*L4"
 		}
 		if x == 14 {
-			continue L4 // ERROR "invalid continue label .*L4"
+			continue L4 // ERROR "invalid continue label .*L4|continue is not in a loop"
 		}
 		if x == 15 {
 			goto L4
@@ -67,7 +73,7 @@ L5:
 		break L5 // ERROR "invalid break label .*L5"
 	}
 	if x == 17 {
-		continue L5 // ERROR "invalid continue label .*L5"
+		continue L5 // ERROR "invalid continue label .*L5|continue is not in a loop"
 	}
 	if x == 18 {
 		goto L5
@@ -84,4 +90,21 @@ L5:
 			goto L1
 		}
 	}
+
+	continue // ERROR "continue is not in a loop"
+	for {
+		continue on // ERROR "continue label not defined: on"
+	}
+
+	break // ERROR "break is not in a loop"
+	for {
+		break dance // ERROR "break label not defined: dance"
+	}
+
+	for {
+		switch x {
+		case 1:
+			continue
+		}
+	}
 }