cmd/asm/internal/asm: fix a bug in ARM assembly encoding test

It is expected to test assembly code for ARMv5, ARMv6 and ARMv7
in cmd/asm/internal/asm/endtoend_test.go. But actually the loop
in "func TestARMEndToEnd(t *testing.T)" runs three times all
for ARMv5.

This patch fixes that bug and adds a new armv6.s which is only tested
with GOARM=6.

fixes #20465

Change-Id: I5dbf00809a47ace2c195335e2c9bdd768479aada
Reviewed-on: https://go-review.googlesource.com/43930Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -19,6 +19,7 @@ import (
 
 	"cmd/asm/internal/lex"
 	"cmd/internal/obj"
+	"cmd/internal/objabi"
 )
 
 // An end-to-end test for the assembler: Do we print what we parse?
@@ -352,22 +353,23 @@ func testErrors(t *testing.T, goarch, file string) {
 }
 
 func Test386EndToEnd(t *testing.T) {
-	defer os.Setenv("GO386", os.Getenv("GO386"))
-
-	for _, go386 := range []string{"387", "sse"} {
-		os.Setenv("GO386", go386)
-		t.Logf("GO386=%v", os.Getenv("GO386"))
+	defer func(old string) { objabi.GO386 = old }(objabi.GO386)
+	for _, go386 := range []string{"387", "sse2"} {
+		t.Logf("GO386=%v", go386)
+		objabi.GO386 = go386
 		testEndToEnd(t, "386", "386")
 	}
 }
 
 func TestARMEndToEnd(t *testing.T) {
-	defer os.Setenv("GOARM", os.Getenv("GOARM"))
-
-	for _, goarm := range []string{"5", "6", "7"} {
-		os.Setenv("GOARM", goarm)
-		t.Logf("GOARM=%v", os.Getenv("GOARM"))
+	defer func(old int) { objabi.GOARM = old }(objabi.GOARM)
+	for _, goarm := range []int{5, 6, 7} {
+		t.Logf("GOARM=%d", goarm)
+		objabi.GOARM = goarm
 		testEndToEnd(t, "arm", "arm")
+		if goarm == 6 {
+			testEndToEnd(t, "arm", "armv6")
+		}
 	}
 }
 

src/cmd/asm/internal/asm/testdata/armv6.s

+// Copyright 2017 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.
+
+#include "../../../../../runtime/textflag.h"
+
+TEXT	foo(SB), DUPOK|NOSPLIT, $0
+
+	ADDF	F0, F1, F2    // 002a31ee
+	ADDD.EQ	F3, F4, F5    // 035b340e
+	ADDF.NE	F0, F2        // 002a321e
+	ADDD	F3, F5        // 035b35ee
+	SUBF	F0, F1, F2    // 402a31ee
+	SUBD.EQ	F3, F4, F5    // 435b340e
+	SUBF.NE	F0, F2        // 402a321e
+	SUBD	F3, F5        // 435b35ee
+	MULF	F0, F1, F2    // 002a21ee
+	MULD.EQ	F3, F4, F5    // 035b240e
+	MULF.NE	F0, F2        // 002a221e
+	MULD	F3, F5        // 035b25ee
+	DIVF	F0, F1, F2    // 002a81ee
+	DIVD.EQ	F3, F4, F5    // 035b840e
+	DIVF.NE	F0, F2        // 002a821e
+	DIVD	F3, F5        // 035b85ee
+	NEGF	F0, F1        // 401ab1ee
+	NEGD	F4, F5        // 445bb1ee
+	ABSF	F0, F1        // c01ab0ee
+	ABSD	F4, F5        // c45bb0ee
+	SQRTF	F0, F1        // c01ab1ee
+	SQRTD	F4, F5        // c45bb1ee
+	MOVFD	F0, F1        // c01ab7ee
+	MOVDF	F4, F5        // c45bb7ee
+
+	LDREX	(R8), R9      // 9f9f98e1
+	LDREXD	(R11), R12    // 9fcfbbe1
+	STREX	R3, (R4), R5  // STREX  (R4), R3, R5 // 935f84e1
+	STREXD	R8, (R9), g   // STREXD (R9), R8, g  // 98afa9e1
+
+	CMPF    F8, F9        // c89ab4ee10faf1ee
+	CMPD.CS F4, F5        // c45bb42e10faf12e
+	CMPF.VS F7            // c07ab56e10faf16e
+	CMPD    F6            // c06bb5ee10faf1ee
+
+	END