runtime: support ia64 in lfstack

    
    Patch by Andreas Schwab.
    
    Reviewed-on: https://go-review.googlesource.com/45071

From-SVN: r248994

gcc/go/gofrontend/MERGE

-7e3904e4370ccfd9062c2661c612476288244e17
+eaf4afbabcd91df55d31955500b6db55b07f6de5
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/runtime/lfstack_64bit.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build amd64 arm64 mips64 mips64le ppc64 ppc64le s390x arm64be alpha mipsn64 sparc64
+// +build amd64 arm64 mips64 mips64le ppc64 ppc64le s390x arm64be alpha mipsn64 sparc64 ia64
 
 package runtime
 
@@ -38,12 +38,22 @@ const (
 	// room in the bottom for the count.
 	sparcLinuxAddrBits = 52
 	sparcLinuxCntBits  = 64 - sparcLinuxAddrBits + 3
+
+	// On IA64, the virtual address space is devided into 8 regions, with
+	// 52 address bits each (with 64k page size).
+	ia64AddrBits = 55
+	ia64CntBits  = 64 - ia64AddrBits + 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))
 	}
+	if GOARCH == "ia64" {
+		// Top three bits are the region number
+		val := uint64(uintptr(unsafe.Pointer(node)))
+		return (val<<(64-ia64AddrBits))&(1<<(64-3)-1) | val&^(1<<(64-3)-1) | uint64(cnt&(1<<ia64CntBits-1))
+	}
 	return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
 }
 
@@ -56,5 +66,8 @@ func lfstackUnpack(val uint64) *lfnode {
 	if GOARCH == "sparc64" && GOOS == "linux" {
 		return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> sparcLinuxCntBits << 3)))
 	}
+	if GOARCH == "ia64" {
+		return (*lfnode)(unsafe.Pointer(uintptr((val>>ia64CntBits<<3)&(1<<(64-3)-1) | val&^(1<<(64-3)-1))))
+	}
 	return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
 }