cmd/internal/obj: fix tail call in non-zero frame leaf function on MIPS and S390X

cherrymui · cherrymui · commit 67917c3d7800 · 2021-12-13T22:42:08.000Z
A "RET f(SB)" wasn't assembled correctly in a leaf function with non-zero frame size. Follows CL 371034, for MIPS(32/64)(be/le) and S390X. Other architectures seem to do it right. Add a test. Change-Id: I41349a7ae9862b924f3a3de2bcb55b782061ce21 Reviewed-on: https://go-review.googlesource.com/c/go/+/371214 Trust: Cherry Mui <cherryyz@google.com> Run-TryBot: Cherry Mui <cherryyz@google.com> Reviewed-by: David Chase <drchase@google.com>
diff --git a/src/cmd/internal/obj/mips/obj0.go b/src/cmd/internal/obj/mips/obj0.go
@@ -466,9 +466,15 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				q = c.newprog()
 				q.As = AJMP
 				q.Pos = p.Pos
-				q.To.Type = obj.TYPE_MEM
-				q.To.Offset = 0
-				q.To.Reg = REGLINK
+				if retSym != nil { // retjmp
+					q.To.Type = obj.TYPE_BRANCH
+					q.To.Name = obj.NAME_EXTERN
+					q.To.Sym = retSym
+				} else {
+					q.To.Type = obj.TYPE_MEM
+					q.To.Reg = REGLINK
+					q.To.Offset = 0
+				}
 				q.Mark |= BRANCH
 				q.Spadj = +autosize
 
diff --git a/src/cmd/internal/obj/s390x/objz.go b/src/cmd/internal/obj/s390x/objz.go
@@ -488,8 +488,13 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				q = obj.Appendp(p, c.newprog)
 				q.As = ABR
 				q.From = obj.Addr{}
-				q.To.Type = obj.TYPE_REG
-				q.To.Reg = REG_LR
+				if retTarget == nil {
+					q.To.Type = obj.TYPE_REG
+					q.To.Reg = REG_LR
+				} else {
+					q.To.Type = obj.TYPE_BRANCH
+					q.To.Sym = retTarget
+				}
 				q.Mark |= BRANCH
 				q.Spadj = autosize
 				break
diff --git a/test/retjmp.dir/a.s b/test/retjmp.dir/a.s
@@ -10,3 +10,7 @@ TEXT	·f(SB), 4, $8-0
 TEXT	·leaf(SB), 4, $0-0
 	RET	·f3(SB)
 	JMP	·unreachable(SB)
+
+TEXT	·leaf2(SB), 4, $32-0 // nonzero frame size
+	RET	·f4(SB)
+	JMP	·unreachable(SB)
diff --git a/test/retjmp.dir/main.go b/test/retjmp.dir/main.go
@@ -6,8 +6,9 @@ package main
 
 func f()
 func leaf()
+func leaf2()
 
-var f1called, f2called, f3called bool
+var f1called, f2called, f3called, f4called bool
 
 func main() {
 	f()
@@ -21,11 +22,16 @@ func main() {
 	if !f3called {
 		panic("f3 not called")
 	}
+	leaf2()
+	if !f4called {
+		panic("f4 not called")
+	}
 }
 
 func f1() { f1called = true }
 func f2() { f2called = true }
 func f3() { f3called = true }
+func f4() { f4called = true }
 
 func unreachable() {
 	panic("unreachable function called")
