cmd/internal/obj/ppc64: add support for pcalign 32 on ppc64x

Previous PCALIGN support on ppc64x only accepted 8 and 16 byte
alignment since the default function alignment was 16. Now that
the function's alignment can be set to a larger value when needed,
PCALIGN can accept 32. When this happens then the function's
alignment will be changed to 32.

Test has been updated to recognized this new value.

Change-Id: If82c3cd50d7c686fcf8a9e819708b15660cdfa63
Reviewed-on: https://go-review.googlesource.com/c/go/+/227775
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/internal/obj/ppc64/asm9.go

@@ -620,7 +620,7 @@ var oprange [ALAST & obj.AMask][]Optab
 var xcmp [C_NCLASS][C_NCLASS]bool
 
 // padding bytes to add to align code as requested
-func addpad(pc, a int64, ctxt *obj.Link) int {
+func addpad(pc, a int64, ctxt *obj.Link, cursym *obj.LSym) int {
 	switch a {
 	case 8:
 		if pc&7 != 0 {
@@ -633,6 +633,21 @@ func addpad(pc, a int64, ctxt *obj.Link) int {
 		case 8:
 			return 8
 		}
+	case 32:
+		switch pc & 31 {
+		case 4, 20:
+			return 12
+		case 8, 24:
+			return 8
+		case 12, 28:
+			return 4
+		}
+		// The default function alignment is 16, but
+		// if 32 byte alignment is requested then the
+		// function needs to be aligned to 32.
+		if cursym.Func.Align < 32 {
+			cursym.Func.Align = 32
+		}
 	default:
 		ctxt.Diag("Unexpected alignment: %d for PCALIGN directive\n", a)
 	}
@@ -663,7 +678,7 @@ func span9(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 		if m == 0 {
 			if p.As == obj.APCALIGN {
 				a := c.vregoff(&p.From)
-				m = addpad(pc, a, ctxt)
+				m = addpad(pc, a, ctxt, cursym)
 			} else {
 				if p.As != obj.ANOP && p.As != obj.AFUNCDATA && p.As != obj.APCDATA {
 					ctxt.Diag("zero-width instruction\n%v", p)
@@ -721,7 +736,7 @@ func span9(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 			if m == 0 {
 				if p.As == obj.APCALIGN {
 					a := c.vregoff(&p.From)
-					m = addpad(pc, a, ctxt)
+					m = addpad(pc, a, ctxt, cursym)
 				} else {
 					if p.As != obj.ANOP && p.As != obj.AFUNCDATA && p.As != obj.APCDATA {
 						ctxt.Diag("zero-width instruction\n%v", p)
@@ -736,10 +751,6 @@ func span9(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 		c.cursym.Size = pc
 	}
 
-	if r := pc & funcAlignMask; r != 0 {
-		pc += funcAlign - r
-	}
-
 	c.cursym.Size = pc
 
 	/*
@@ -761,7 +772,7 @@ func span9(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 		if o.type_ == 0 && p.As == obj.APCALIGN {
 			pad := LOP_RRR(OP_OR, REGZERO, REGZERO, REGZERO)
 			aln := c.vregoff(&p.From)
-			v := addpad(p.Pc, aln, c.ctxt)
+			v := addpad(p.Pc, aln, c.ctxt, c.cursym)
 			if v > 0 {
 				// Same padding instruction for all
 				for i = 0; i < int32(v/4); i++ {

src/cmd/internal/obj/ppc64/asm_test.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"testing"
 )
@@ -17,21 +18,20 @@ import (
 var invalidPCAlignSrc = `
 TEXT test(SB),0,$0-0
 ADD $2, R3
-PCALIGN $32
+PCALIGN $64
 RET
 `
+
 var validPCAlignSrc = `
 TEXT test(SB),0,$0-0
 ADD $2, R3
 PCALIGN $16
-MOVD $8, R4
+MOVD $8, R16
-ADD $8, R4
-PCALIGN $16
 ADD $8, R4
+PCALIGN $32
+ADD $8, R3
 PCALIGN $8
-ADD $4, R6
+ADD $4, R8
-PCALIGN $16
-ADD R2, R3, R4
 RET
 `
 
@@ -39,6 +39,10 @@ RET
 // PCALIGN directive, to verify correct values are and
 // accepted, and incorrect values are flagged in error.
 func TestPCalign(t *testing.T) {
+	var pattern8 = `0x...8\s.*ADD\s..,\sR8`
+	var pattern16 = `0x...[80]\s.*MOVD\s..,\sR16`
+	var pattern32 = `0x...0\s.*ADD\s..,\sR3`
+
 	testenv.MustHaveGoBuild(t)
 
 	dir, err := ioutil.TempDir("", "testpcalign")
@@ -63,6 +67,30 @@ func TestPCalign(t *testing.T) {
 		t.Errorf("Build failed: %v, output: %s", err, out)
 	}
 
+	matched, err := regexp.MatchString(pattern8, string(out))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !matched {
+		t.Errorf("The 8 byte alignment is not correct: %t, output:%s\n", matched, out)
+	}
+
+	matched, err = regexp.MatchString(pattern16, string(out))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !matched {
+		t.Errorf("The 16 byte alignment is not correct: %t, output:%s\n", matched, out)
+	}
+
+	matched, err = regexp.MatchString(pattern32, string(out))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !matched {
+		t.Errorf("The 32 byte alignment is not correct: %t, output:%s\n", matched, out)
+	}
+
 	// generate a test with invalid use of PCALIGN
 
 	tmpfile = filepath.Join(dir, "xi.s")