From 4f813b81013fcd1bef4a980b78e7fe19cdc2adfe Mon Sep 17 00:00:00 2001
From: aarzilli <alessandro.arzilli@gmail.com>
Date: Fri, 27 Oct 2017 17:00:41 +0200
Subject: [PATCH] proc, terminal: use DW_AT_producer to warn user about
 optimized code

---
 pkg/proc/bininfo.go        | 6 ++++++
 pkg/proc/types.go          | 4 ++++
 pkg/terminal/command.go    | 8 ++++++++
 service/api/conversions.go | 9 +++++----
 service/api/types.go       | 2 ++
 5 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/pkg/proc/bininfo.go b/pkg/proc/bininfo.go
index 1a411187..d7b7c50f 100644
--- a/pkg/proc/bininfo.go
+++ b/pkg/proc/bininfo.go
@@ -72,6 +72,7 @@ type compileUnit struct {
 	Name          string              // univocal name for non-go compile units
 	lineInfo      *line.DebugLineInfo // debug_line segment associated with this compile unit
 	LowPC, HighPC uint64
+	optimized     bool // this compile unit is optimized
 }
 
 // Function describes a function in the target program.
@@ -126,6 +127,11 @@ func (fn *Function) BaseName() string {
 	return fn.Name
 }
 
+// Optimized returns true if the function was optimized by the compiler.
+func (fn *Function) Optimized() bool {
+	return fn.cu.optimized
+}
+
 type constantsMap map[dwarf.Offset]*constantType
 
 type constantType struct {
diff --git a/pkg/proc/types.go b/pkg/proc/types.go
index c6378f40..114cd5db 100644
--- a/pkg/proc/types.go
+++ b/pkg/proc/types.go
@@ -204,6 +204,10 @@ func (bi *BinaryInfo) loadDebugInfoMaps(debugLineBytes []byte, wg *sync.WaitGrou
 			if lineInfoOffset >= 0 && lineInfoOffset < int64(len(debugLineBytes)) {
 				cu.lineInfo = line.Parse(compdir, bytes.NewBuffer(debugLineBytes[lineInfoOffset:]))
 			}
+			if producer, _ := entry.Val(dwarf.AttrProducer).(string); cu.isgo && producer != "" {
+				semicolon := strings.Index(producer, ";")
+				cu.optimized = semicolon < 0 || !strings.Contains(producer[semicolon:], "-N") || !strings.Contains(producer[semicolon:], "-l")
+			}
 			bi.compileUnits = append(bi.compileUnits, cu)
 
 		case dwarf.TagArrayType, dwarf.TagBaseType, dwarf.TagClassType, dwarf.TagStructType, dwarf.TagUnionType, dwarf.TagConstType, dwarf.TagVolatileType, dwarf.TagRestrictType, dwarf.TagEnumerationType, dwarf.TagPointerType, dwarf.TagSubroutineType, dwarf.TagTypedef, dwarf.TagUnspecifiedType:
diff --git a/pkg/terminal/command.go b/pkg/terminal/command.go
index ff8e5b6e..6d2ca864 100644
--- a/pkg/terminal/command.go
+++ b/pkg/terminal/command.go
@@ -23,6 +23,8 @@ import (
 	"github.com/derekparker/delve/service/debugger"
 )
 
+const optimizedFunctionWarning = "Warning: debugging optimized function"
+
 type cmdPrefix int
 
 const (
@@ -1353,6 +1355,9 @@ func printcontextThread(t *Term, th *api.Thread) {
 
 	if th.Breakpoint == nil {
 		fmt.Printf("> %s() %s:%d (PC: %#v)\n", fn.Name, ShortenFilePath(th.File), th.Line, th.PC)
+		if th.Function != nil && th.Function.Optimized {
+			fmt.Println(optimizedFunctionWarning)
+		}
 		return
 	}
 
@@ -1391,6 +1396,9 @@ func printcontextThread(t *Term, th *api.Thread) {
 			th.Breakpoint.TotalHitCount,
 			th.PC)
 	}
+	if th.Function != nil && th.Function.Optimized {
+		fmt.Println(optimizedFunctionWarning)
+	}
 
 	if th.BreakpointInfo != nil {
 		bp := th.Breakpoint
diff --git a/service/api/conversions.go b/service/api/conversions.go
index 36c3123d..8745cad3 100644
--- a/service/api/conversions.go
+++ b/service/api/conversions.go
@@ -212,10 +212,11 @@ func ConvertFunction(fn *proc.Function) *Function {
 	// those fields is not documented their value was replaced with 0 when
 	// gosym.Func was replaced by debug_info entries.
 	return &Function{
-		Name:   fn.Name,
-		Type:   0,
-		Value:  fn.Entry,
-		GoType: 0,
+		Name:      fn.Name,
+		Type:      0,
+		Value:     fn.Entry,
+		GoType:    0,
+		Optimized: fn.Optimized(),
 	}
 }
 
diff --git a/service/api/types.go b/service/api/types.go
index 3bcba150..a6ce44ba 100644
--- a/service/api/types.go
+++ b/service/api/types.go
@@ -148,6 +148,8 @@ type Function struct {
 	Value  uint64 `json:"value"`
 	Type   byte   `json:"type"`
 	GoType uint64 `json:"goType"`
+	// Optimized is true if the function was optimized
+	Optimized bool `json:"optimized"`
 }
 
 // VariableFlags is the type of the Flags field of Variable.
-- 
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