libgo: support for sparc64 GNU/Linux

    
    Fix lfstack code to work with sparc64 GNU/Linux address map.
    
    Force alignment of epollevent.  To make this work reliably, pass
    GOARCH explicitly to mkrsysinfo.sh.
    
    Patch by Vladimir Mezentsev.
    
    Reviewed-on: https://go-review.googlesource.com/44494

From-SVN: r248765

gcc/go/gofrontend/MERGE

-884df09c3da0f39309ab13f2ad401628fb933050
+e5870eac67d4d5b1f86bdbfb13dadf4d5723f71d
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/Makefile.am

@@ -531,7 +531,7 @@ s-version: Makefile
 
 runtime_sysinfo.go: s-runtime_sysinfo; @true
 s-runtime_sysinfo: $(srcdir)/mkrsysinfo.sh gen-sysinfo.go
-	GOOS=$(GOOS) $(SHELL) $(srcdir)/mkrsysinfo.sh
+	GOARCH=$(GOARCH) GOOS=$(GOOS) $(SHELL) $(srcdir)/mkrsysinfo.sh
 	$(SHELL) $(srcdir)/mvifdiff.sh tmp-runtime_sysinfo.go runtime_sysinfo.go
 	$(STAMP) $@
 

libgo/Makefile.in

@@ -3081,7 +3081,7 @@ s-version: Makefile
 
 runtime_sysinfo.go: s-runtime_sysinfo; @true
 s-runtime_sysinfo: $(srcdir)/mkrsysinfo.sh gen-sysinfo.go
-	GOOS=$(GOOS) $(SHELL) $(srcdir)/mkrsysinfo.sh
+	GOARCH=$(GOARCH) GOOS=$(GOOS) $(SHELL) $(srcdir)/mkrsysinfo.sh
 	$(SHELL) $(srcdir)/mvifdiff.sh tmp-runtime_sysinfo.go runtime_sysinfo.go
 	$(STAMP) $@
 

libgo/go/runtime/lfstack_64bit.go

@@ -32,9 +32,18 @@ const (
 	// bottom, because node must be pointer-aligned, giving a total of 19 bits
 	// of count.
 	cntBits = 64 - addrBits + 3
+
+	// On sparc64-linux, user addresses are 52-bit numbers sign extended to 64.
+	// We shift the address left 12 to eliminate the sign extended part and make
+	// room in the bottom for the count.
+	sparcLinuxAddrBits = 52
+	sparcLinuxCntBits  = 64 - sparcLinuxAddrBits + 3
 )
 
 func lfstackPack(node *lfnode, cnt uintptr) uint64 {
+	if GOARCH == "sparc64" && GOOS == "linux" {
+		return uint64(uintptr(unsafe.Pointer(node)))<<(64-sparcLinuxAddrBits) | uint64(cnt&(1<<sparcLinuxCntBits-1))
+	}
 	return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
 }
 
@@ -44,5 +53,8 @@ func lfstackUnpack(val uint64) *lfnode {
 		// val before unpacking.
 		return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> cntBits << 3)))
 	}
+	if GOARCH == "sparc64" && GOOS == "linux" {
+		return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> sparcLinuxCntBits << 3)))
+	}
 	return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
 }

libgo/mkrsysinfo.sh

@@ -83,7 +83,11 @@ if grep '^const _epoll_data_offset ' ${OUT} >/dev/null 2>&1; then
   if test "$val" = "4"; then
       echo 'type epollevent struct { events uint32; data [8]byte }' >> ${OUT}
   elif test "$val" = "8"; then
-      echo 'type epollevent struct { events uint32; pad [4]byte; data [8]byte }' >> ${OUT}
+      if test "$GOARCH" = "sparc64" -a "$GOOS" = "linux"; then
+          echo 'type epollevent struct { events uint32; pad [4]byte; data [8]byte; _align [0]int64 }' >> ${OUT}
+      else
+          echo 'type epollevent struct { events uint32; pad [4]byte; data [8]byte }' >> ${OUT}
+      fi
   else
       echo 1>&2 "unknown epoll data offset value ${val}"
       exit 1