pkg/proc: split off rangeParent from function extras (#4173)

The rangeParent calculation was changed 0b74953f0 to address slowness
(due to repeated calculations) when calling PackageVariables. That
changed caused to program to use a lot of memory due to having to
calculate the range bodies of every function. This change reverts
0b74953f0 and splits off rangeBodies calculation from the extras method
of Function, so that it isn't called from PackageVariables.

Fixes #4146

pkg/proc/bininfo.go

@@ -25,9 +25,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/derekparker/trie/v3"
-	"github.com/hashicorp/golang-lru/v2"
-
 	"github.com/go-delve/delve/pkg/astutil"
 	pdwarf "github.com/go-delve/delve/pkg/dwarf"
 	"github.com/go-delve/delve/pkg/dwarf/frame"
@@ -41,6 +38,7 @@ import (
 	"github.com/go-delve/delve/pkg/logflags"
 	"github.com/go-delve/delve/pkg/proc/debuginfod"
 	"github.com/go-delve/delve/pkg/proc/evalop"
+	"github.com/hashicorp/golang-lru/v2"
 )
 
 const (
@@ -69,8 +67,6 @@ type BinaryInfo struct {
 	// lookupGenericFunc maps function names, with their type parameters removed, to functions.
 	// Functions that are not generic are not added to this map.
 	lookupGenericFunc map[string][]*Function
-	// lookupRangeBodyFunc maps function names to the range body functions.
-	lookupRangeBodyFunc *trie.Trie[*Function]
 
 	// SymNames maps addr to a description *elf.Symbol of this addr.
 	SymNames map[uint64]*elf.Symbol
@@ -536,19 +532,18 @@ type Function struct {
 	// extraCache contains information about this function that is only needed for
 	// some operations and is expensive to compute or store for every function.
 	extraCache *functionExtra
+	// rangeBodiesCache caches the list of range-over-func body closures for
+	// this function. Only one of extraCache.rangeParent and rangeBodiesCache
+	// should be set at any given time.
+	rangeBodiesCache []*Function
 }
 
 type functionExtra struct {
 	// closureStructType is the cached struct type for closures for this function
 	closureStructType *godwarf.StructType
-
 	// rangeParent is set when this function is a range-over-func body closure
 	// and points to the function that the closure was generated from.
 	rangeParent *Function
-	// rangeBodies is the list of range-over-func body closures for this
-	// function. Only one between rangeParent and rangeBodies should be set at
-	// any given time.
-	rangeBodies []*Function
 }
 
 // instRange returns the indexes in fn.Name of the type parameter
@@ -776,19 +771,31 @@ func (fn *Function) extra(bi *BinaryInfo) *functionExtra {
 		fn.extraCache.rangeParent = bi.lookupOneFunc(rangeParentName)
 	}
 
-	// Find range-over-func bodies of this function
-	if fn.extraCache.rangeParent == nil {
-		lookupFunc := bi.LookupRangeBodyFunc()
-		for _, fn2 := range lookupFunc.PrefixSearchIter(fn.Name) {
-			if fn2.rangeParentName() == fn.Name {
-				fn.extraCache.rangeBodies = append(fn.extraCache.rangeBodies, fn2)
-			}
-		}
-	}
-
 	return fn.extraCache
 }
 
+// rangeBodies returns the list of range-over-func body closures for this
+// function.
+func (fn *Function) rangeBodies(bi *BinaryInfo) []*Function {
+	if fn == nil {
+		return nil
+	}
+	if fn.rangeBodiesCache != nil {
+		return fn.rangeBodiesCache
+	}
+	extra := fn.extra(bi)
+	if extra.rangeParent != nil {
+		return nil
+	}
+	for i := range bi.Functions {
+		fn2 := &bi.Functions[i]
+		if strings.HasPrefix(fn2.Name, fn.Name) && fn2.rangeParentName() == fn.Name {
+			fn.rangeBodiesCache = append(fn.rangeBodiesCache, fn2)
+		}
+	}
+	return fn.rangeBodiesCache
+}
+
 type constantsMap map[dwarfRef]*constantType
 
 type constantType struct {
@@ -2626,7 +2633,6 @@ func (bi *BinaryInfo) loadDebugInfoMaps(image *Image, debugInfoBytes, debugLineB
 
 	bi.lookupFunc = nil
 	bi.lookupGenericFunc = nil
-	bi.lookupRangeBodyFunc = nil
 
 	for _, cu := range image.compileUnits {
 		if cu.lineInfo != nil {
@@ -2672,16 +2678,6 @@ func (bi *BinaryInfo) LookupFunc() map[string][]*Function {
 	return bi.lookupFunc
 }
 
-func (bi *BinaryInfo) LookupRangeBodyFunc() *trie.Trie[*Function] {
-	if bi.lookupRangeBodyFunc == nil {
-		bi.lookupRangeBodyFunc = trie.New[*Function]()
-		for i := range bi.Functions {
-			bi.lookupRangeBodyFunc.Add(bi.Functions[i].Name, &bi.Functions[i])
-		}
-	}
-	return bi.lookupRangeBodyFunc
-}
-
 func (bi *BinaryInfo) lookupOneFunc(name string) *Function {
 	if name == evalop.DebugPinnerFunctionName && bi.debugPinnerFn != nil {
 		return bi.debugPinnerFn

pkg/proc/target_exec.go

@@ -855,7 +855,7 @@ func next(dbp *Target, stepInto, inlinedStepOut bool) error {
 			rpoff = rangeFrames[len(rangeFrames)-2].FrameOffset()
 		}
 		rpc := astutil.And(sameGCond, astutil.Eql(astutil.PkgVar("runtime", "rangeParentOffset"), astutil.Int(rpoff)))
-		for _, fn := range rangeParent.extra(bi).rangeBodies {
+		for _, fn := range rangeParent.rangeBodies(bi) {
 			if fn.Entry != 0 {
 				pc, err := FirstPCAfterPrologue(dbp, fn, false)
 				if err != nil {

pkg/proc/types.go

@@ -149,7 +149,7 @@ func dwarfToRuntimeType(bi *BinaryInfo, mem MemoryReadWriter, typ godwarf.Type)
 		return 0, false, false, nil
 	}
 
-	mds, err := bi.getModuleData(mem)
+	mds, err := LoadModuleData(bi, mem)
 	if err != nil {
 		return 0, false, false, err
 	}

pkg/proc/variables.go

@@ -2141,7 +2141,7 @@ func (v *Variable) loadInterface(recurseLevel int, loadData bool, cfg LoadConfig
 		return
 	}
 
-	mds, err := _type.bi.getModuleData(_type.mem)
+	mds, err := LoadModuleData(_type.bi, _type.mem)
 	if err != nil {
 		v.Unreadable = fmt.Errorf("error loading module data: %v", err)
 		return