cmd/asm: fix assembling return jump

In RET instruction, the operand is the return jump's target,
which should be put in Prog.To.

Add an action "buildrundir" to the test driver, which builds
(compile+assemble+link) the code in a directory and runs the
resulting binary.

Fixes #23838.

Change-Id: I7ebe7eda49024b40a69a24857322c5ca9c67babb
Reviewed-on: https://go-review.googlesource.com/94175
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

src/cmd/asm/internal/asm/asm.go

@@ -486,7 +486,7 @@ func (p *Parser) asmInstruction(op obj.As, cond string, a []obj.Addr) {
 	case 0:
 		// Nothing to do.
 	case 1:
-		if p.arch.UnaryDst[op] {
+		if p.arch.UnaryDst[op] || op == obj.ARET {
 			// prog.From is no address.
 			prog.To = a[0]
 		} else {

src/cmd/asm/internal/asm/testdata/386.s

@@ -91,3 +91,4 @@ loop:
 
 // LTYPE0 nonnon	{ outcode(int($1), &$2); }
 	RET
+	RET	foo(SB)

src/cmd/asm/internal/asm/testdata/amd64.s

@@ -145,3 +145,4 @@ loop:
 
 // LTYPE0 nonnon	{ outcode($1, &$2); }
 	RET // c3
+	RET	foo(SB)

src/cmd/asm/internal/asm/testdata/arm.s

@@ -1579,6 +1579,8 @@ jmp_label_3:
 	MOVHU	R5@>16, R1                                        // 7518ffe6
 	MOVHU	R5@>24, R1                                        // 751cffe6
 
+	RET	foo(SB)
+
 //
 // END
 //

src/cmd/asm/internal/asm/testdata/arm64.s

@@ -426,6 +426,7 @@ again:
 //	}
 	BEQ	2(PC)
 	RET
+	RET	foo(SB)
 
 // More B/BL cases, and canonical names JMP, CALL.
 

src/cmd/asm/internal/asm/testdata/mips.s

@@ -422,6 +422,7 @@ label4:
 	BEQ	R1, 2(PC)
 	JMP	foo(SB)
 	CALL	foo(SB)
+	RET	foo(SB)
 
 	NEGW	R1, R2 // 00011023
 

src/cmd/asm/internal/asm/testdata/mips64.s

@@ -402,6 +402,7 @@ label4:
 	BEQ	R1, 2(PC)
 	JMP	foo(SB)
 	CALL	foo(SB)
+	RET	foo(SB)
 
 	NEGW	R1, R2 // 00011023
 	NEGV	R1, R2 // 0001102f

src/cmd/asm/internal/asm/testdata/ppc64.s

@@ -1197,6 +1197,7 @@ label1:
 	BEQ	2(PC)
 	JMP	foo(SB)
 	CALL	foo(SB)
+	RET	foo(SB)
 
 // END
 //

src/cmd/asm/internal/asm/testdata/s390x.s

@@ -365,6 +365,7 @@ TEXT main·foo(SB),DUPOK|NOSPLIT,$16-0 // TEXT main.foo(SB), DUPOK|NOSPLIT, $16-
 	VSTEB	$15, V29, 4094(R12)     // e7d0cffef808
 
 	RET
+	RET	foo(SB)
 
 TEXT main·init(SB),DUPOK|NOSPLIT,$0 // TEXT main.init(SB), DUPOK|NOSPLIT, $0
 	RET

test/retjmp.dir/a.s

@@ -0,0 +1,12 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+TEXT	·f(SB), 4, $8-0
+	CALL	·f1(SB)
+	RET	·f2(SB)
+	CALL	·unreachable(SB)
+
+TEXT	·leaf(SB), 4, $0-0
+	RET	·f3(SB)
+	JMP	·unreachable(SB)

test/retjmp.dir/main.go

@@ -0,0 +1,32 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f()
+func leaf()
+
+var f1called, f2called, f3called bool
+
+func main() {
+	f()
+	if !f1called {
+		panic("f1 not called")
+	}
+	if !f2called {
+		panic("f2 not called")
+	}
+	leaf()
+	if !f3called {
+		panic("f3 not called")
+	}
+}
+
+func f1() { f1called = true }
+func f2() { f2called = true }
+func f3() { f3called = true }
+
+func unreachable() {
+	panic("unreachable function called")
+}

test/retjmp.go

@@ -0,0 +1,9 @@
+// buildrundir
+
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that return jump works correctly in assembly code.
+
+package ignored

test/run.go

@@ -488,7 +488,7 @@ func (t *test) run() {
 		action = "rundir"
 	case "cmpout":
 		action = "run" // the run case already looks for <dir>/<test>.out files
-	case "compile", "compiledir", "build", "builddir", "run", "buildrun", "runoutput", "rundir", "asmcheck":
+	case "compile", "compiledir", "build", "builddir", "buildrundir", "run", "buildrun", "runoutput", "rundir", "asmcheck":
 		// nothing to do
 	case "errorcheckandrundir":
 		wantError = false // should be no error if also will run
@@ -735,7 +735,7 @@ func (t *test) run() {
 			t.err = err
 		}
 
-	case "builddir":
+	case "builddir", "buildrundir":
 		// Build an executable from all the .go and .s files in a subdirectory.
 		useTmp = true
 		longdir := filepath.Join(cwd, t.goDirName())
@@ -788,12 +788,23 @@ func (t *test) run() {
 			t.err = err
 			break
 		}
-		cmd = []string{"go", "tool", "link", "all.a"}
+		cmd = []string{"go", "tool", "link", "-o", "a.exe", "all.a"}
 		_, err = runcmd(cmd...)
 		if err != nil {
 			t.err = err
 			break
 		}
+		if action == "buildrundir" {
+			cmd = append(findExecCmd(), filepath.Join(t.tempDir, "a.exe"))
+			out, err := runcmd(cmd...)
+			if err != nil {
+				t.err = err
+				break
+			}
+			if strings.Replace(string(out), "\r\n", "\n", -1) != t.expectedOutput() {
+				t.err = fmt.Errorf("incorrect output\n%s", out)
+			}
+		}
 
 	case "buildrun": // build binary, then run binary, instead of go run. Useful for timeout tests where failure mode is infinite loop.
 		// TODO: not supported on NaCl