Add compact tables snapshot tests (#1250)

* testdata: Update

To include parca-dev/testdata@c0d23d5

Signed-off-by: Francisco Javier Honduvilla Coto <javierhonduco@gmail.com>

* .eh_frame: Add snapshot tests for compact unwind table

Signed-off-by: Francisco Javier Honduvilla Coto <javierhonduco@gmail.com>

Author: javierhonduco

Makefile

@@ -132,6 +132,7 @@ $(OUT_BIN_EH_FRAME): go/deps
 
 write-dwarf-unwind-tables: build
 	make -C testdata validate EH_FRAME_BIN=../dist/eh-frame
+	make -C testdata validate-compact EH_FRAME_BIN=../dist/eh-frame
 
 test-dwarf-unwind-tables: write-dwarf-unwind-tables
 	$(CMD_GIT) diff --exit-code testdata/

cmd/eh-frame/main.go

@@ -26,6 +26,7 @@ import (
 
 type flags struct {
 	Executable string `kong:"help='The executable to print the .eh_unwind tables for.'"`
+	Compact    bool   `kong:"help='Whether to use the compact format.'"`
 }
 
 // This tool exists for debugging .eh_frame unwinding and its intended for Parca Agent's
@@ -45,7 +46,7 @@ func main() {
 	}
 
 	ptb := unwind.NewUnwindTableBuilder(logger)
-	err := ptb.PrintTable(os.Stdout, executablePath)
+	err := ptb.PrintTable(os.Stdout, executablePath, flags.Compact)
 	if err != nil {
 		// nolint
 		fmt.Println("failed with:", err)

pkg/stack/unwind/unwind_table.go

@@ -182,7 +182,7 @@ func x64RegisterToString(reg uint64) string {
 }
 
 // PrintTable is a debugging helper that prints the unwinding table to the given io.Writer.
-func (ptb *UnwindTableBuilder) PrintTable(writer io.Writer, path string) error {
+func (ptb *UnwindTableBuilder) PrintTable(writer io.Writer, path string, compact bool) error {
 	fdes, err := ptb.readFDEs(path)
 	if err != nil {
 		return err
@@ -206,39 +206,55 @@ func (ptb *UnwindTableBuilder) PrintTable(writer io.Writer, path string) error {
 			if unwindRow == nil {
 				break
 			}
-			//nolint:exhaustive
-			switch unwindRow.CFA.Rule {
-			case frame.RuleCFA:
-				CFAReg := x64RegisterToString(unwindRow.CFA.Reg)
-				fmt.Fprintf(writer, "\tLoc: %x CFA: $%s=%-4d", unwindRow.Loc, CFAReg, unwindRow.CFA.Offset)
-			case frame.RuleExpression:
-				expressionID := ExpressionIdentifier(unwindRow.CFA.Expression)
-				if expressionID == ExpressionUnknown {
-					fmt.Fprintf(writer, "\tLoc: %x CFA: exp     ", unwindRow.Loc)
-				} else {
-					fmt.Fprintf(writer, "\tLoc: %x CFA: exp (plt %d)", unwindRow.Loc, expressionID)
+
+			if compact {
+				compactRow, err := rowToCompactRow(unwindRow)
+				if err != nil {
+					return err
 				}
-			default:
-				return multierror.Append(fmt.Errorf("CFA rule is not valid. This should never happen"))
-			}
 
-			// RuleRegister
-			//nolint:exhaustive
-			switch unwindRow.RBP.Rule {
-			case frame.RuleUndefined, frame.RuleUnknown:
-				fmt.Fprintf(writer, "\tRBP: u")
-			case frame.RuleRegister:
-				RBPReg := x64RegisterToString(unwindRow.RBP.Reg)
-				fmt.Fprintf(writer, "\tRBP: $%s", RBPReg)
-			case frame.RuleOffset:
-				fmt.Fprintf(writer, "\tRBP: c%-4d", unwindRow.RBP.Offset)
-			case frame.RuleExpression:
-				fmt.Fprintf(writer, "\tRBP: exp")
-			default:
-				panic(fmt.Sprintf("Got rule %d for RBP, which wasn't expected", unwindRow.RBP.Rule))
-			}
+				fmt.Fprintf(writer, "\t")
+				fmt.Fprintf(writer, "pc: %x ", compactRow.Pc())
+				fmt.Fprintf(writer, "cfa_type: %-2d ", compactRow.CfaType())
+				fmt.Fprintf(writer, "rbp_type: %-2d ", compactRow.RbpType())
+				fmt.Fprintf(writer, "cfa_offset: %-4d ", compactRow.CfaOffset())
+				fmt.Fprintf(writer, "rbp_offset: %-4d", compactRow.RbpOffset())
+				fmt.Fprintf(writer, "\n")
+			} else {
+				//nolint:exhaustive
+				switch unwindRow.CFA.Rule {
+				case frame.RuleCFA:
+					CFAReg := x64RegisterToString(unwindRow.CFA.Reg)
+					fmt.Fprintf(writer, "\tLoc: %x CFA: $%s=%-4d", unwindRow.Loc, CFAReg, unwindRow.CFA.Offset)
+				case frame.RuleExpression:
+					expressionID := ExpressionIdentifier(unwindRow.CFA.Expression)
+					if expressionID == ExpressionUnknown {
+						fmt.Fprintf(writer, "\tLoc: %x CFA: exp     ", unwindRow.Loc)
+					} else {
+						fmt.Fprintf(writer, "\tLoc: %x CFA: exp (plt %d)", unwindRow.Loc, expressionID)
+					}
+				default:
+					return multierror.Append(fmt.Errorf("CFA rule is not valid. This should never happen"))
+				}
 
-			fmt.Fprintf(writer, "\n")
+				// RuleRegister
+				//nolint:exhaustive
+				switch unwindRow.RBP.Rule {
+				case frame.RuleUndefined, frame.RuleUnknown:
+					fmt.Fprintf(writer, "\tRBP: u")
+				case frame.RuleRegister:
+					RBPReg := x64RegisterToString(unwindRow.RBP.Reg)
+					fmt.Fprintf(writer, "\tRBP: $%s", RBPReg)
+				case frame.RuleOffset:
+					fmt.Fprintf(writer, "\tRBP: c%-4d", unwindRow.RBP.Offset)
+				case frame.RuleExpression:
+					fmt.Fprintf(writer, "\tRBP: exp")
+				default:
+					panic(fmt.Sprintf("Got rule %d for RBP, which wasn't expected", unwindRow.RBP.Rule))
+				}
+
+				fmt.Fprintf(writer, "\n")
+			}
 		}
 	}