cmd/link: scope test to linux & net.sendFile

Limits the scope of new test added in 71c2bf551303930faa32886446910fa5bd0a701a.

Discussion: https://go-review.googlesource.com/c/go/+/684377.

Change-Id: I0e8f513eb564aae277ba8a80ebdad469eb1e6e6a
GitHub-Last-Rev: add2b2e2096e5221ac3d54376c1afa1bec10482c
GitHub-Pull-Request: golang/go#74720
Reviewed-on: https://go-review.googlesource.com/c/go/+/689916
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Keith Randall <khr@google.com>

diff --git a/src/cmd/compile/internal/dwarfgen/dwarf.go b/src/cmd/compile/internal/dwarfgen/dwarf.go
index af2b191010e4c0f79fca1b429afed07a1959c4d9..7d75c0c5ce38d7778671501fa7c8919ee6f6a12b 100644 (file)
--- a/src/cmd/compile/internal/dwarfgen/dwarf.go
+++ b/src/cmd/compile/internal/dwarfgen/dwarf.go
@@ -278,7 +278,7 @@ func createDwarfVars(fnsym *obj.LSym, complexOK bool, fn *ir.Func, apDecls []*ir
                                base.Fatalf("invalid heap allocated var without Heapaddr")
                        }
                        debug := fn.DebugInfo.(*ssa.FuncDebug)
-                       list := createHeapDerefLocationList(n, fnsym, debug.EntryID, ssa.FuncEnd.ID)
+                       list := createHeapDerefLocationList(n, debug.EntryID)
                        dvar.PutLocationList = func(listSym, startPC dwarf.Sym) {
                                debug.PutLocationList(list, base.Ctxt, listSym.(*obj.LSym), startPC.(*obj.LSym))
                        }
@@ -558,7 +558,7 @@ func createComplexVar(fnsym *obj.LSym, fn *ir.Func, varID ssa.VarID, closureVars
 
 // createHeapDerefLocationList creates a location list for a heap-escaped variable
 // that describes "dereference pointer at stack offset"
-func createHeapDerefLocationList(n *ir.Name, fnsym *obj.LSym, entryID, prologEndID ssa.ID) []byte {
+func createHeapDerefLocationList(n *ir.Name, entryID ssa.ID) []byte {
        // Get the stack offset where the heap pointer is stored
        heapPtrOffset := n.Heapaddr.FrameOffset()
        if base.Ctxt.Arch.FixedFrameSize == 0 {

diff --git a/src/cmd/link/dwarf_test.go b/src/cmd/link/dwarf_test.go
index 4305354d1691b605fe3f23646fafe92b558ed937..d269aa70c61ac9ebfb3f6e53505370d57a64e52e 100644 (file)
--- a/src/cmd/link/dwarf_test.go
+++ b/src/cmd/link/dwarf_test.go
@@ -257,7 +257,18 @@ func TestDWARFiOS(t *testing.T) {
        })
 }
 
+// This test ensures that variables promoted to the heap, specifically
+// function return parameters, have correct location lists generated.
+//
+// TODO(deparker): This test is intentionally limited to GOOS=="linux"
+// and scoped to net.sendFile, which was the function reported originally in
+// issue #65405. There is relevant discussion in https://go-review.googlesource.com/c/go/+/684377
+// pertaining to these limitations. There are other missing location lists which must be fixed
+// particularly in functions where `linkname` is involved.
 func TestDWARFLocationList(t *testing.T) {
+       if runtime.GOOS != "linux" {
+               t.Skip("skipping test on non-linux OS")
+       }
        testenv.MustHaveCGO(t)
        testenv.MustHaveGoBuild(t)
 
@@ -305,22 +316,10 @@ func TestDWARFLocationList(t *testing.T) {
                // Look for the net.sendFile subprogram
                if entry.Tag == dwarf.TagSubprogram {
                        fnName, ok := entry.Val(dwarf.AttrName).(string)
-                       if !ok {
+                       if !ok || fnName != "net.sendFile" {
+                               reader.SkipChildren()
                                continue
                        }
-                       if strings.Contains(fnName, ".eq") || // Ignore autogenerated equality funcs
-                               strings.HasPrefix(fnName, "internal/") || // Ignore internal/runtime package TODO(deparker): Fix these too (likely same issue as other ignored packages below).
-                               strings.HasPrefix(fnName, "runtime.") || // Ignore runtime package which contain funcs implemented in assembly or exposed through linkname which seems to not generate location lists correctly (most likely linkname causing this). TODO(deparker) Fix these too.
-                               strings.HasPrefix(fnName, "reflect.") || // Ignore reflect package. TODO(deparker) Fix these too.
-                               strings.HasPrefix(fnName, "time.") { // Ignore funcs in time package which are exposed through linkname and seem to not generate location lists correctly TODO(deparker) Fix these too.
-                               continue
-                       }
-                       if fnName == "syscall.compileCallback" || fnName == "maps.clone" {
-                               continue // Ignore for now, possibly caused by linkname usage. TODO(deparker) Fix this too.
-                       }
-                       if runtime.GOOS == "windows" && strings.HasPrefix(fnName, "syscall.") {
-                               continue // Ignore, caused by linkname usage. TODO(deparker) Fix these too.
-                       }
 
                        for {
                                paramEntry, err := reader.Next()
@@ -332,13 +331,8 @@ func TestDWARFLocationList(t *testing.T) {
                                }
 
                                if paramEntry.Tag == dwarf.TagFormalParameter {
-                                       paramName, hasName := paramEntry.Val(dwarf.AttrName).(string)
-                                       if !hasName {
-                                               continue
-                                       }
-                                       if paramName[0] == '~' {
-                                               continue
-                                       }
+                                       paramName, _ := paramEntry.Val(dwarf.AttrName).(string)
+
                                        // Check if this parameter has a location attribute
                                        if loc := paramEntry.Val(dwarf.AttrLocation); loc != nil {
                                                switch locData := loc.(type) {