fix: re-sort collection summaries after inferring usage

.github/workflows/ci.yaml

@@ -22,7 +22,7 @@ jobs:
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v9
         with:
-          version: v2.11
+          version: v2.13
   # Run go test to ensure tests pass
   gotest:
     name: tests

cmd/stackwhere/list_test.go

@@ -110,6 +110,32 @@ func TestListCollectionIncludesInstructionOnlyStackUsage(t *testing.T) {
 	}
 }
 
+func TestListCollectionSortsAfterInferringStackUsage(t *testing.T) {
+	cmd := root()
+	cmd.SetArgs([]string{"list", "../../testdata/noinline.o", "-j"})
+
+	var stdout bytes.Buffer
+	cmd.SetOut(&stdout)
+
+	if err := cmd.Execute(); err != nil {
+		t.Fatalf("list command failed: %v", err)
+	}
+
+	var got []stackview.ProgramStackUsage
+	if err := json.Unmarshal(stdout.Bytes(), &got); err != nil {
+		t.Fatalf("failed to decode JSON output: %v", err)
+	}
+
+	want := []stackview.ProgramStackUsage{
+		{Name: "entry", StackUsage: 8},
+		{Name: "z_known", StackUsage: 8},
+		{Name: "helper", StackUsage: 0},
+	}
+	if !slices.Equal(got, want) {
+		t.Fatalf("unexpected JSON output: got %#v want %#v", got, want)
+	}
+}
+
 func TestListCollectionIncludesVoidFunction(t *testing.T) {
 	cmd := root()
 	cmd.SetArgs([]string{"list", "../../testdata/noinline.o"})

internal/stackview/stackview.go

@@ -112,7 +112,7 @@ func (a *Analyzer) CollectionSummaryInCollection() ([]ProgramStackUsage, error)
 	}
 
 	summary := a.CollectionSummary()
-	filtered := make([]ProgramStackUsage, 0, len(summary))
+	stackUsagePerProgram := make(map[string]int64, len(summary))
 	subProgsDwarf := a.tree.ByType(dbgdwarf.TagSubprogram)
 	for _, prog := range summary {
 		fn, ok := a.functions[prog.Name]
@@ -128,10 +128,10 @@ func (a *Analyzer) CollectionSummaryInCollection() ([]ProgramStackUsage, error)
 			prog.StackUsage = max(prog.StackUsage, inferredUsage)
 		}
 
-		filtered = append(filtered, prog)
+		stackUsagePerProgram[prog.Name] = prog.StackUsage
 	}
 
-	return filtered, nil
+	return SortProgramStackUsage(stackUsagePerProgram), nil
 }
 
 func stackUsageFromSlots(slots slotList) int64 {

testdata/noinline.c

@@ -1,5 +1,6 @@
 #define __section(X) __attribute__((section(X), used))
 #define __noinline __attribute__((noinline))
+#define force_on_stack(x) asm volatile("" :: "r"(&(x)))
 
 static __noinline void helper(int *value)
 {
@@ -13,3 +14,11 @@ __section("tc") int entry(void *ctx)
 	helper(&value);
 	return value;
 }
+
+__section("tc/known") int z_known(void *ctx)
+{
+	long value = 0;
+
+	force_on_stack(value);
+	return value;
+}