cmd/compile/internal/ssagen,runtime: merge trace consts into internal/abi

For #59670

src/cmd/compile/internal/ssagen/ssa.go

@@ -7109,24 +7109,7 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 	//   - 0xfb - print _ (offset too large)
 	// These constants need to be in sync with runtime.traceback.go:printArgs.
 	const (
-		_endSeq         = 0xff
-		_startAgg       = 0xfe
-		_endAgg         = 0xfd
-		_dotdotdot      = 0xfc
-		_offsetTooLarge = 0xfb
-		_special        = 0xf0 // above this are operators, below this are ordinary offsets
-	)
-
-	const (
-		limit    = 10 // print no more than 10 args/components
-		maxDepth = 5  // no more than 5 layers of nesting
-
-		// maxLen is a (conservative) upper bound of the byte stream length. For
-		// each arg/component, it has no more than 2 bytes of data (size, offset),
-		// and no more than one {, }, ... at each level (it cannot have both the
-		// data and ... unless it is the last one, just be conservative). Plus 1
-		// for _endSeq.
-		maxLen = (maxDepth*3+2)*limit + 1
+		_special = 0xf0 // above this are operators, below this are ordinary offsets
 	)
 
 	wOff := 0
@@ -7136,7 +7119,7 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 	// Write one non-aggregate arg/field/element.
 	write1 := func(sz, offset int64) {
 		if offset >= _special {
-			writebyte(_offsetTooLarge)
+			writebyte(rtabi.TraceArgsOffsetTooLarge)
 		} else {
 			writebyte(uint8(offset))
 			writebyte(uint8(sz))
@@ -7148,19 +7131,19 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 	// Returns whether to continue visiting.
 	var visitType func(baseOffset int64, t *types.Type, depth int) bool
 	visitType = func(baseOffset int64, t *types.Type, depth int) bool {
-		if n >= limit {
-			writebyte(_dotdotdot)
+		if n >= rtabi.TraceArgsLimit {
+			writebyte(rtabi.TraceArgsDotdotdot)
 			return false
 		}
 		if !isAggregate(t) {
 			write1(t.Size(), baseOffset)
 			return true
 		}
-		writebyte(_startAgg)
+		writebyte(rtabi.TraceArgsStartAgg)
 		depth++
-		if depth >= maxDepth {
-			writebyte(_dotdotdot)
-			writebyte(_endAgg)
+		if depth >= rtabi.TraceArgsMaxDepth {
+			writebyte(rtabi.TraceArgsDotdotdot)
+			writebyte(rtabi.TraceArgsEndAgg)
 			n++
 			return true
 		}
@@ -7197,7 +7180,7 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 				}
 			}
 		}
-		writebyte(_endAgg)
+		writebyte(rtabi.TraceArgsEndAgg)
 		return true
 	}
 
@@ -7212,8 +7195,8 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 			break
 		}
 	}
-	writebyte(_endSeq)
-	if wOff > maxLen {
+	writebyte(rtabi.TraceArgsEndSeq)
+	if wOff > rtabi.TraceArgsMaxLen {
 		base.Fatalf("ArgInfo too large")
 	}
 

src/internal/abi/type.go

@@ -710,3 +710,23 @@ func NewName(n, tag string, exported, embedded bool) Name {
 
 	return Name{Bytes: &b[0]}
 }
+
+const (
+	TraceArgsLimit    = 10 // print no more than 10 args/components
+	TraceArgsMaxDepth = 5  // no more than 5 layers of nesting
+
+	// maxLen is a (conservative) upper bound of the byte stream length. For
+	// each arg/component, it has no more than 2 bytes of data (size, offset),
+	// and no more than one {, }, ... at each level (it cannot have both the
+	// data and ... unless it is the last one, just be conservative). Plus 1
+	// for _endSeq.
+	TraceArgsMaxLen = (TraceArgsMaxDepth*3+2)*TraceArgsLimit + 1
+)
+
+const (
+	TraceArgsEndSeq         = 0xff
+	TraceArgsStartAgg       = 0xfe
+	TraceArgsEndAgg         = 0xfd
+	TraceArgsDotdotdot      = 0xfc
+	TraceArgsOffsetTooLarge = 0xfb
+)

src/runtime/traceback.go

@@ -650,25 +650,7 @@ func tracebackPCs(u *unwinder, skip int, pcBuf []uintptr) int {
 
 // printArgs prints function arguments in traceback.
 func printArgs(f funcInfo, argp unsafe.Pointer, pc uintptr) {
-	// The "instruction" of argument printing is encoded in _FUNCDATA_ArgInfo.
-	// See cmd/compile/internal/ssagen.emitArgInfo for the description of the
-	// encoding.
-	// These constants need to be in sync with the compiler.
-	const (
-		_endSeq         = 0xff
-		_startAgg       = 0xfe
-		_endAgg         = 0xfd
-		_dotdotdot      = 0xfc
-		_offsetTooLarge = 0xfb
-	)
-
-	const (
-		limit    = 10                       // print no more than 10 args/components
-		maxDepth = 5                        // no more than 5 layers of nesting
-		maxLen   = (maxDepth*3+2)*limit + 1 // max length of _FUNCDATA_ArgInfo (see the compiler side for reasoning)
-	)
-
-	p := (*[maxLen]uint8)(funcdata(f, abi.FUNCDATA_ArgInfo))
+	p := (*[abi.TraceArgsMaxLen]uint8)(funcdata(f, abi.FUNCDATA_ArgInfo))
 	if p == nil {
 		return
 	}
@@ -721,19 +703,19 @@ printloop:
 		o := p[pi]
 		pi++
 		switch o {
-		case _endSeq:
+		case abi.TraceArgsEndSeq:
 			break printloop
-		case _startAgg:
+		case abi.TraceArgsStartAgg:
 			printcomma()
 			print("{")
 			start = true
 			continue
-		case _endAgg:
+		case abi.TraceArgsEndAgg:
 			print("}")
-		case _dotdotdot:
+		case abi.TraceArgsDotdotdot:
 			printcomma()
 			print("...")
-		case _offsetTooLarge:
+		case abi.TraceArgsOffsetTooLarge:
 			printcomma()
 			print("_")
 		default: