Add instruction based stack slot usage analysis

cmd/stackwhere/list_test.go

@@ -1,18 +1,28 @@
 package main
 
 import (
+	"slices"
 	"testing"
 
+	"github.com/cilium/ebpf"
 	"github.com/cilium/stackwhere/internal/dwarf"
 )
 
-func TestGetStackSlotUsage(t *testing.T) {
+func TestGetStackSlotUsageFromDWARF(t *testing.T) {
 	tree, err := dwarf.NewDWARFTree("../../testdata/basic.o")
 	if err != nil {
 		t.Fatalf("failed to parse DWARF data: %v", err)
 	}
 
-	stackUsage := getStackSlotUsage(tree, "cil_entry")
+	subProgs := tree.ByType(dwarf.TagSubprogram)
+	idx := slices.IndexFunc(subProgs, func(n *dwarf.Node) bool {
+		return n.Name() == "cil_entry"
+	})
+	if idx == -1 {
+		t.Fatalf("failed to find subprogram node for cil_entry")
+	}
+
+	stackUsage := stackSlotsFromDWARFVars(subProgs[idx])
 	if len(stackUsage) != 3 {
 		t.Fatalf("expected 3 stack slots, got %d", len(stackUsage))
 	}
@@ -72,6 +82,69 @@ func TestGetStackSlotUsage(t *testing.T) {
 	}
 }
 
+func TestGetStackSlotUsageFromInsns(t *testing.T) {
+	tree, err := dwarf.NewDWARFTree("../../testdata/spill.o")
+	if err != nil {
+		t.Fatalf("failed to parse DWARF data: %v", err)
+	}
+
+	spec, err := ebpf.LoadCollectionSpec("../../testdata/spill.o")
+	if err != nil {
+		t.Fatalf("failed to load collection spec: %v", err)
+	}
+
+	subProgs := tree.ByType(dwarf.TagSubprogram)
+	idx := slices.IndexFunc(subProgs, func(n *dwarf.Node) bool {
+		return n.Name() == "cil_entry"
+	})
+	if idx == -1 {
+		t.Fatalf("failed to find subprogram node for cil_entry")
+	}
+
+	stackUsage := stackSlotsFromInsns(spec.Programs["cil_entry"], subProgs[idx])
+	if len(stackUsage) != 1 {
+		t.Fatalf("expected 1 stack slot group, got %d", len(stackUsage))
+	}
+
+	// Verify each stack slot group contains expected slots
+	slotGroups := []struct {
+		index    int
+		expected map[string]int64
+	}{
+		{
+			index: 0,
+			expected: map[string]int64{
+				"r2": -1,
+			},
+		},
+	}
+
+	for _, group := range slotGroups {
+		found := make(map[string]int64)
+		for _, slot := range stackUsage[group.index] {
+			found[slot.Name] = slot.ByteSize
+		}
+
+		// Check all expected slots are present with correct size
+		for name, expectedSize := range group.expected {
+			actualSize, ok := found[name]
+			if !ok {
+				t.Errorf("slot group %d: expected slot %q not found", group.index, name)
+				continue
+			}
+			if actualSize != expectedSize {
+				t.Errorf("slot group %d: slot %q has size %d, expected %d", group.index, name, actualSize, expectedSize)
+			}
+			delete(found, name)
+		}
+
+		// Check no unexpected slots are present
+		if len(found) > 0 {
+			t.Errorf("slot group %d: unexpected slots found: %v", group.index, found)
+		}
+	}
+}
+
 func TestGetProgramStackUsage(t *testing.T) {
 	tree, err := dwarf.NewDWARFTree("../../testdata/basic.o")
 	if err != nil {

go.mod

@@ -3,11 +3,13 @@ module github.com/cilium/stackwhere
 go 1.25.0
 
 require (
-	github.com/davecgh/go-spew v1.1.1
+	github.com/cilium/ebpf v0.21.0
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc
 	github.com/spf13/cobra v1.10.2
 )
 
 require (
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/spf13/pflag v1.0.9 // indirect
+	golang.org/x/sys v0.37.0 // indirect
 )

go.sum

@@ -1,12 +1,28 @@
+github.com/cilium/ebpf v0.21.0 h1:4dpx1J/B/1apeTmWBH5BkVLayHTkFrMovVPnHEk+l3k=
+github.com/cilium/ebpf v0.21.0/go.mod h1:1kHKv6Kvh5a6TePP5vvvoMa1bclRyzUXELSs272fmIQ=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
+github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-quicktest/qt v1.101.1-0.20240301121107-c6c8733fa1e6 h1:teYtXy9B7y5lHTp8V9KPxpYRAVA7dozigQcMiBust1s=
+github.com/go-quicktest/qt v1.101.1-0.20240301121107-c6c8733fa1e6/go.mod h1:p4lGIVX+8Wa6ZPNDvqcxq36XpUDLh42FLetFU7odllI=
+github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
+github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/rogpeppe/go-internal v1.12.0 h1:exVL4IDcn6na9z1rAb56Vxr+CgyK3nn3O+epU5NdKM8=
+github.com/rogpeppe/go-internal v1.12.0/go.mod h1:E+RYuTGaKKdloAfM02xzb0FW3Paa99yedzYV+kq4uf4=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/spf13/cobra v1.10.2 h1:DMTTonx5m65Ic0GOoRY2c16WCbHxOOw6xxezuLaBpcU=
 github.com/spf13/cobra v1.10.2/go.mod h1:7C1pvHqHw5A4vrJfjNwvOdzYu0Gml16OCs2GRiTUUS4=
 github.com/spf13/pflag v1.0.9 h1:9exaQaMOCwffKiiiYk6/BndUBv+iRViNW+4lEMi0PvY=
 github.com/spf13/pflag v1.0.9/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
+golang.org/x/sync v0.17.0 h1:l60nONMj9l5drqw6jlhIELNv9I0A4OFgRsG9k2oT9Ug=
+golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/sys v0.37.0 h1:fdNQudmxPjkdUTPnLn5mdQv7Zwvbvpaxqs831goi9kQ=
+golang.org/x/sys v0.37.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

internal/dwarf/loclist.go

@@ -175,6 +175,7 @@ func NewLoclistTable(f *elf.File) (*LoclistTable, error) {
 	}
 
 	if f.Class != elf.ELFCLASS64 {
+		// Code should work, but untested
 		return nil, fmt.Errorf("unexpected 32-bit ELF file")
 	}