diff --git a/src/cmd/compile/internal/gc/builtin.go b/src/cmd/compile/internal/gc/builtin.go
index 71b323f8a1..70200c624b 100644
--- a/src/cmd/compile/internal/gc/builtin.go
+++ b/src/cmd/compile/internal/gc/builtin.go
@@ -12,229 +12,228 @@ var runtimeDecls = [...]struct {
 	{"panicslice", funcTag, 5},
 	{"panicdivide", funcTag, 5},
 	{"throwinit", funcTag, 5},
-	{"panicwrap", funcTag, 7},
-	{"gopanic", funcTag, 9},
-	{"gorecover", funcTag, 12},
+	{"panicwrap", funcTag, 5},
+	{"gopanic", funcTag, 7},
+	{"gorecover", funcTag, 10},
 	{"goschedguarded", funcTag, 5},
-	{"printbool", funcTag, 14},
-	{"printfloat", funcTag, 16},
-	{"printint", funcTag, 18},
-	{"printhex", funcTag, 20},
-	{"printuint", funcTag, 20},
-	{"printcomplex", funcTag, 22},
-	{"printstring", funcTag, 23},
-	{"printpointer", funcTag, 24},
-	{"printiface", funcTag, 24},
-	{"printeface", funcTag, 24},
-	{"printslice", funcTag, 24},
+	{"printbool", funcTag, 12},
+	{"printfloat", funcTag, 14},
+	{"printint", funcTag, 16},
+	{"printhex", funcTag, 18},
+	{"printuint", funcTag, 18},
+	{"printcomplex", funcTag, 20},
+	{"printstring", funcTag, 22},
+	{"printpointer", funcTag, 23},
+	{"printiface", funcTag, 23},
+	{"printeface", funcTag, 23},
+	{"printslice", funcTag, 23},
 	{"printnl", funcTag, 5},
 	{"printsp", funcTag, 5},
 	{"printlock", funcTag, 5},
 	{"printunlock", funcTag, 5},
-	{"concatstring2", funcTag, 27},
-	{"concatstring3", funcTag, 28},
-	{"concatstring4", funcTag, 29},
-	{"concatstring5", funcTag, 30},
-	{"concatstrings", funcTag, 32},
-	{"cmpstring", funcTag, 34},
-	{"eqstring", funcTag, 35},
-	{"intstring", funcTag, 38},
-	{"slicebytetostring", funcTag, 40},
-	{"slicebytetostringtmp", funcTag, 41},
-	{"slicerunetostring", funcTag, 44},
-	{"stringtoslicebyte", funcTag, 45},
-	{"stringtoslicerune", funcTag, 48},
-	{"decoderune", funcTag, 49},
-	{"slicecopy", funcTag, 51},
-	{"slicestringcopy", funcTag, 52},
-	{"convI2I", funcTag, 53},
-	{"convT2E", funcTag, 54},
-	{"convT2I", funcTag, 54},
-	{"assertE2I", funcTag, 53},
-	{"assertE2I2", funcTag, 55},
-	{"assertI2I", funcTag, 53},
-	{"assertI2I2", funcTag, 55},
-	{"panicdottype", funcTag, 56},
-	{"panicnildottype", funcTag, 57},
-	{"ifaceeq", funcTag, 58},
-	{"efaceeq", funcTag, 58},
-	{"makemap", funcTag, 60},
-	{"mapaccess1", funcTag, 61},
-	{"mapaccess1_fast32", funcTag, 62},
-	{"mapaccess1_fast64", funcTag, 62},
-	{"mapaccess1_faststr", funcTag, 62},
-	{"mapaccess1_fat", funcTag, 63},
-	{"mapaccess2", funcTag, 64},
-	{"mapaccess2_fast32", funcTag, 65},
-	{"mapaccess2_fast64", funcTag, 65},
-	{"mapaccess2_faststr", funcTag, 65},
-	{"mapaccess2_fat", funcTag, 66},
-	{"mapassign", funcTag, 61},
-	{"mapiterinit", funcTag, 67},
-	{"mapdelete", funcTag, 67},
-	{"mapiternext", funcTag, 68},
-	{"makechan", funcTag, 70},
-	{"chanrecv1", funcTag, 72},
-	{"chanrecv2", funcTag, 73},
-	{"chansend1", funcTag, 75},
-	{"closechan", funcTag, 24},
-	{"writeBarrier", varTag, 76},
-	{"writebarrierptr", funcTag, 77},
-	{"typedmemmove", funcTag, 78},
-	{"typedmemclr", funcTag, 79},
-	{"typedslicecopy", funcTag, 80},
-	{"selectnbsend", funcTag, 81},
-	{"selectnbrecv", funcTag, 82},
-	{"selectnbrecv2", funcTag, 84},
-	{"newselect", funcTag, 85},
-	{"selectsend", funcTag, 81},
-	{"selectrecv", funcTag, 73},
-	{"selectrecv2", funcTag, 86},
-	{"selectdefault", funcTag, 87},
-	{"selectgo", funcTag, 57},
+	{"concatstring2", funcTag, 26},
+	{"concatstring3", funcTag, 27},
+	{"concatstring4", funcTag, 28},
+	{"concatstring5", funcTag, 29},
+	{"concatstrings", funcTag, 31},
+	{"cmpstring", funcTag, 33},
+	{"eqstring", funcTag, 34},
+	{"intstring", funcTag, 37},
+	{"slicebytetostring", funcTag, 39},
+	{"slicebytetostringtmp", funcTag, 40},
+	{"slicerunetostring", funcTag, 43},
+	{"stringtoslicebyte", funcTag, 44},
+	{"stringtoslicerune", funcTag, 47},
+	{"decoderune", funcTag, 48},
+	{"slicecopy", funcTag, 50},
+	{"slicestringcopy", funcTag, 51},
+	{"convI2I", funcTag, 52},
+	{"convT2E", funcTag, 53},
+	{"convT2I", funcTag, 53},
+	{"assertE2I", funcTag, 52},
+	{"assertE2I2", funcTag, 54},
+	{"assertI2I", funcTag, 52},
+	{"assertI2I2", funcTag, 54},
+	{"panicdottype", funcTag, 55},
+	{"panicnildottype", funcTag, 56},
+	{"ifaceeq", funcTag, 57},
+	{"efaceeq", funcTag, 57},
+	{"makemap", funcTag, 59},
+	{"mapaccess1", funcTag, 60},
+	{"mapaccess1_fast32", funcTag, 61},
+	{"mapaccess1_fast64", funcTag, 61},
+	{"mapaccess1_faststr", funcTag, 61},
+	{"mapaccess1_fat", funcTag, 62},
+	{"mapaccess2", funcTag, 63},
+	{"mapaccess2_fast32", funcTag, 64},
+	{"mapaccess2_fast64", funcTag, 64},
+	{"mapaccess2_faststr", funcTag, 64},
+	{"mapaccess2_fat", funcTag, 65},
+	{"mapassign", funcTag, 60},
+	{"mapiterinit", funcTag, 66},
+	{"mapdelete", funcTag, 66},
+	{"mapiternext", funcTag, 67},
+	{"makechan", funcTag, 69},
+	{"chanrecv1", funcTag, 71},
+	{"chanrecv2", funcTag, 72},
+	{"chansend1", funcTag, 74},
+	{"closechan", funcTag, 23},
+	{"writeBarrier", varTag, 75},
+	{"writebarrierptr", funcTag, 76},
+	{"typedmemmove", funcTag, 77},
+	{"typedmemclr", funcTag, 78},
+	{"typedslicecopy", funcTag, 79},
+	{"selectnbsend", funcTag, 80},
+	{"selectnbrecv", funcTag, 81},
+	{"selectnbrecv2", funcTag, 83},
+	{"newselect", funcTag, 84},
+	{"selectsend", funcTag, 80},
+	{"selectrecv", funcTag, 72},
+	{"selectrecv2", funcTag, 85},
+	{"selectdefault", funcTag, 86},
+	{"selectgo", funcTag, 56},
 	{"block", funcTag, 5},
-	{"makeslice", funcTag, 89},
-	{"makeslice64", funcTag, 90},
-	{"growslice", funcTag, 91},
-	{"memmove", funcTag, 92},
-	{"memclrNoHeapPointers", funcTag, 93},
-	{"memclrHasPointers", funcTag, 93},
-	{"memequal", funcTag, 94},
-	{"memequal8", funcTag, 95},
-	{"memequal16", funcTag, 95},
-	{"memequal32", funcTag, 95},
-	{"memequal64", funcTag, 95},
-	{"memequal128", funcTag, 95},
-	{"int64div", funcTag, 96},
-	{"uint64div", funcTag, 97},
-	{"int64mod", funcTag, 96},
-	{"uint64mod", funcTag, 97},
-	{"float64toint64", funcTag, 98},
-	{"float64touint64", funcTag, 99},
-	{"float64touint32", funcTag, 101},
-	{"int64tofloat64", funcTag, 102},
-	{"uint64tofloat64", funcTag, 103},
-	{"uint32tofloat64", funcTag, 104},
-	{"complex128div", funcTag, 105},
-	{"racefuncenter", funcTag, 106},
+	{"makeslice", funcTag, 88},
+	{"makeslice64", funcTag, 89},
+	{"growslice", funcTag, 90},
+	{"memmove", funcTag, 91},
+	{"memclrNoHeapPointers", funcTag, 92},
+	{"memclrHasPointers", funcTag, 92},
+	{"memequal", funcTag, 93},
+	{"memequal8", funcTag, 94},
+	{"memequal16", funcTag, 94},
+	{"memequal32", funcTag, 94},
+	{"memequal64", funcTag, 94},
+	{"memequal128", funcTag, 94},
+	{"int64div", funcTag, 95},
+	{"uint64div", funcTag, 96},
+	{"int64mod", funcTag, 95},
+	{"uint64mod", funcTag, 96},
+	{"float64toint64", funcTag, 97},
+	{"float64touint64", funcTag, 98},
+	{"float64touint32", funcTag, 100},
+	{"int64tofloat64", funcTag, 101},
+	{"uint64tofloat64", funcTag, 102},
+	{"uint32tofloat64", funcTag, 103},
+	{"complex128div", funcTag, 104},
+	{"racefuncenter", funcTag, 105},
 	{"racefuncexit", funcTag, 5},
-	{"raceread", funcTag, 106},
-	{"racewrite", funcTag, 106},
-	{"racereadrange", funcTag, 107},
-	{"racewriterange", funcTag, 107},
-	{"msanread", funcTag, 107},
-	{"msanwrite", funcTag, 107},
+	{"raceread", funcTag, 105},
+	{"racewrite", funcTag, 105},
+	{"racereadrange", funcTag, 106},
+	{"racewriterange", funcTag, 106},
+	{"msanread", funcTag, 106},
+	{"msanwrite", funcTag, 106},
 }
 
 func runtimeTypes() []*Type {
-	var typs [108]*Type
+	var typs [107]*Type
 	typs[0] = bytetype
 	typs[1] = typPtr(typs[0])
 	typs[2] = Types[TANY]
 	typs[3] = typPtr(typs[2])
 	typs[4] = functype(nil, []*Node{anonfield(typs[1])}, []*Node{anonfield(typs[3])})
 	typs[5] = functype(nil, nil, nil)
-	typs[6] = Types[TSTRING]
-	typs[7] = functype(nil, []*Node{anonfield(typs[6]), anonfield(typs[6]), anonfield(typs[6])}, nil)
-	typs[8] = Types[TINTER]
-	typs[9] = functype(nil, []*Node{anonfield(typs[8])}, nil)
-	typs[10] = Types[TINT32]
-	typs[11] = typPtr(typs[10])
-	typs[12] = functype(nil, []*Node{anonfield(typs[11])}, []*Node{anonfield(typs[8])})
-	typs[13] = Types[TBOOL]
+	typs[6] = Types[TINTER]
+	typs[7] = functype(nil, []*Node{anonfield(typs[6])}, nil)
+	typs[8] = Types[TINT32]
+	typs[9] = typPtr(typs[8])
+	typs[10] = functype(nil, []*Node{anonfield(typs[9])}, []*Node{anonfield(typs[6])})
+	typs[11] = Types[TBOOL]
+	typs[12] = functype(nil, []*Node{anonfield(typs[11])}, nil)
+	typs[13] = Types[TFLOAT64]
 	typs[14] = functype(nil, []*Node{anonfield(typs[13])}, nil)
-	typs[15] = Types[TFLOAT64]
+	typs[15] = Types[TINT64]
 	typs[16] = functype(nil, []*Node{anonfield(typs[15])}, nil)
-	typs[17] = Types[TINT64]
+	typs[17] = Types[TUINT64]
 	typs[18] = functype(nil, []*Node{anonfield(typs[17])}, nil)
-	typs[19] = Types[TUINT64]
+	typs[19] = Types[TCOMPLEX128]
 	typs[20] = functype(nil, []*Node{anonfield(typs[19])}, nil)
-	typs[21] = Types[TCOMPLEX128]
+	typs[21] = Types[TSTRING]
 	typs[22] = functype(nil, []*Node{anonfield(typs[21])}, nil)
-	typs[23] = functype(nil, []*Node{anonfield(typs[6])}, nil)
-	typs[24] = functype(nil, []*Node{anonfield(typs[2])}, nil)
-	typs[25] = typArray(typs[0], 32)
-	typs[26] = typPtr(typs[25])
-	typs[27] = functype(nil, []*Node{anonfield(typs[26]), anonfield(typs[6]), anonfield(typs[6])}, []*Node{anonfield(typs[6])})
-	typs[28] = functype(nil, []*Node{anonfield(typs[26]), anonfield(typs[6]), anonfield(typs[6]), anonfield(typs[6])}, []*Node{anonfield(typs[6])})
-	typs[29] = functype(nil, []*Node{anonfield(typs[26]), anonfield(typs[6]), anonfield(typs[6]), anonfield(typs[6]), anonfield(typs[6])}, []*Node{anonfield(typs[6])})
-	typs[30] = functype(nil, []*Node{anonfield(typs[26]), anonfield(typs[6]), anonfield(typs[6]), anonfield(typs[6]), anonfield(typs[6]), anonfield(typs[6])}, []*Node{anonfield(typs[6])})
-	typs[31] = typSlice(typs[6])
-	typs[32] = functype(nil, []*Node{anonfield(typs[26]), anonfield(typs[31])}, []*Node{anonfield(typs[6])})
-	typs[33] = Types[TINT]
-	typs[34] = functype(nil, []*Node{anonfield(typs[6]), anonfield(typs[6])}, []*Node{anonfield(typs[33])})
-	typs[35] = functype(nil, []*Node{anonfield(typs[6]), anonfield(typs[6])}, []*Node{anonfield(typs[13])})
-	typs[36] = typArray(typs[0], 4)
-	typs[37] = typPtr(typs[36])
-	typs[38] = functype(nil, []*Node{anonfield(typs[37]), anonfield(typs[17])}, []*Node{anonfield(typs[6])})
-	typs[39] = typSlice(typs[0])
-	typs[40] = functype(nil, []*Node{anonfield(typs[26]), anonfield(typs[39])}, []*Node{anonfield(typs[6])})
-	typs[41] = functype(nil, []*Node{anonfield(typs[39])}, []*Node{anonfield(typs[6])})
-	typs[42] = runetype
-	typs[43] = typSlice(typs[42])
-	typs[44] = functype(nil, []*Node{anonfield(typs[26]), anonfield(typs[43])}, []*Node{anonfield(typs[6])})
-	typs[45] = functype(nil, []*Node{anonfield(typs[26]), anonfield(typs[6])}, []*Node{anonfield(typs[39])})
-	typs[46] = typArray(typs[42], 32)
-	typs[47] = typPtr(typs[46])
-	typs[48] = functype(nil, []*Node{anonfield(typs[47]), anonfield(typs[6])}, []*Node{anonfield(typs[43])})
-	typs[49] = functype(nil, []*Node{anonfield(typs[6]), anonfield(typs[33])}, []*Node{anonfield(typs[42]), anonfield(typs[33])})
-	typs[50] = Types[TUINTPTR]
-	typs[51] = functype(nil, []*Node{anonfield(typs[2]), anonfield(typs[2]), anonfield(typs[50])}, []*Node{anonfield(typs[33])})
-	typs[52] = functype(nil, []*Node{anonfield(typs[2]), anonfield(typs[2])}, []*Node{anonfield(typs[33])})
-	typs[53] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[2])}, []*Node{anonfield(typs[2])})
-	typs[54] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3])}, []*Node{anonfield(typs[2])})
-	typs[55] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[2])}, []*Node{anonfield(typs[2]), anonfield(typs[13])})
-	typs[56] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[1]), anonfield(typs[1])}, nil)
-	typs[57] = functype(nil, []*Node{anonfield(typs[1])}, nil)
-	typs[58] = functype(nil, []*Node{anonfield(typs[2]), anonfield(typs[2])}, []*Node{anonfield(typs[13])})
-	typs[59] = typMap(typs[2], typs[2])
-	typs[60] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[17]), anonfield(typs[3]), anonfield(typs[3])}, []*Node{anonfield(typs[59])})
-	typs[61] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[59]), anonfield(typs[3])}, []*Node{anonfield(typs[3])})
-	typs[62] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[59]), anonfield(typs[2])}, []*Node{anonfield(typs[3])})
-	typs[63] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[59]), anonfield(typs[3]), anonfield(typs[1])}, []*Node{anonfield(typs[3])})
-	typs[64] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[59]), anonfield(typs[3])}, []*Node{anonfield(typs[3]), anonfield(typs[13])})
-	typs[65] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[59]), anonfield(typs[2])}, []*Node{anonfield(typs[3]), anonfield(typs[13])})
-	typs[66] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[59]), anonfield(typs[3]), anonfield(typs[1])}, []*Node{anonfield(typs[3]), anonfield(typs[13])})
-	typs[67] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[59]), anonfield(typs[3])}, nil)
-	typs[68] = functype(nil, []*Node{anonfield(typs[3])}, nil)
-	typs[69] = typChan(typs[2], Cboth)
-	typs[70] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[17])}, []*Node{anonfield(typs[69])})
-	typs[71] = typChan(typs[2], Crecv)
-	typs[72] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[71]), anonfield(typs[3])}, nil)
-	typs[73] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[71]), anonfield(typs[3])}, []*Node{anonfield(typs[13])})
-	typs[74] = typChan(typs[2], Csend)
-	typs[75] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[74]), anonfield(typs[3])}, nil)
-	typs[76] = tostruct([]*Node{namedfield("enabled", typs[13]), namedfield("needed", typs[13]), namedfield("cgo", typs[13])})
-	typs[77] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[2])}, nil)
-	typs[78] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3]), anonfield(typs[3])}, nil)
-	typs[79] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3])}, nil)
-	typs[80] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[2]), anonfield(typs[2])}, []*Node{anonfield(typs[33])})
-	typs[81] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[74]), anonfield(typs[3])}, []*Node{anonfield(typs[13])})
-	typs[82] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3]), anonfield(typs[71])}, []*Node{anonfield(typs[13])})
-	typs[83] = typPtr(typs[13])
-	typs[84] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3]), anonfield(typs[83]), anonfield(typs[71])}, []*Node{anonfield(typs[13])})
-	typs[85] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[17]), anonfield(typs[10])}, nil)
-	typs[86] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[71]), anonfield(typs[3]), anonfield(typs[83])}, []*Node{anonfield(typs[13])})
-	typs[87] = functype(nil, []*Node{anonfield(typs[1])}, []*Node{anonfield(typs[13])})
-	typs[88] = typSlice(typs[2])
-	typs[89] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[33]), anonfield(typs[33])}, []*Node{anonfield(typs[88])})
-	typs[90] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[17]), anonfield(typs[17])}, []*Node{anonfield(typs[88])})
-	typs[91] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[88]), anonfield(typs[33])}, []*Node{anonfield(typs[88])})
-	typs[92] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[3]), anonfield(typs[50])}, nil)
-	typs[93] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[50])}, nil)
-	typs[94] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[3]), anonfield(typs[50])}, []*Node{anonfield(typs[13])})
-	typs[95] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[3])}, []*Node{anonfield(typs[13])})
+	typs[23] = functype(nil, []*Node{anonfield(typs[2])}, nil)
+	typs[24] = typArray(typs[0], 32)
+	typs[25] = typPtr(typs[24])
+	typs[26] = functype(nil, []*Node{anonfield(typs[25]), anonfield(typs[21]), anonfield(typs[21])}, []*Node{anonfield(typs[21])})
+	typs[27] = functype(nil, []*Node{anonfield(typs[25]), anonfield(typs[21]), anonfield(typs[21]), anonfield(typs[21])}, []*Node{anonfield(typs[21])})
+	typs[28] = functype(nil, []*Node{anonfield(typs[25]), anonfield(typs[21]), anonfield(typs[21]), anonfield(typs[21]), anonfield(typs[21])}, []*Node{anonfield(typs[21])})
+	typs[29] = functype(nil, []*Node{anonfield(typs[25]), anonfield(typs[21]), anonfield(typs[21]), anonfield(typs[21]), anonfield(typs[21]), anonfield(typs[21])}, []*Node{anonfield(typs[21])})
+	typs[30] = typSlice(typs[21])
+	typs[31] = functype(nil, []*Node{anonfield(typs[25]), anonfield(typs[30])}, []*Node{anonfield(typs[21])})
+	typs[32] = Types[TINT]
+	typs[33] = functype(nil, []*Node{anonfield(typs[21]), anonfield(typs[21])}, []*Node{anonfield(typs[32])})
+	typs[34] = functype(nil, []*Node{anonfield(typs[21]), anonfield(typs[21])}, []*Node{anonfield(typs[11])})
+	typs[35] = typArray(typs[0], 4)
+	typs[36] = typPtr(typs[35])
+	typs[37] = functype(nil, []*Node{anonfield(typs[36]), anonfield(typs[15])}, []*Node{anonfield(typs[21])})
+	typs[38] = typSlice(typs[0])
+	typs[39] = functype(nil, []*Node{anonfield(typs[25]), anonfield(typs[38])}, []*Node{anonfield(typs[21])})
+	typs[40] = functype(nil, []*Node{anonfield(typs[38])}, []*Node{anonfield(typs[21])})
+	typs[41] = runetype
+	typs[42] = typSlice(typs[41])
+	typs[43] = functype(nil, []*Node{anonfield(typs[25]), anonfield(typs[42])}, []*Node{anonfield(typs[21])})
+	typs[44] = functype(nil, []*Node{anonfield(typs[25]), anonfield(typs[21])}, []*Node{anonfield(typs[38])})
+	typs[45] = typArray(typs[41], 32)
+	typs[46] = typPtr(typs[45])
+	typs[47] = functype(nil, []*Node{anonfield(typs[46]), anonfield(typs[21])}, []*Node{anonfield(typs[42])})
+	typs[48] = functype(nil, []*Node{anonfield(typs[21]), anonfield(typs[32])}, []*Node{anonfield(typs[41]), anonfield(typs[32])})
+	typs[49] = Types[TUINTPTR]
+	typs[50] = functype(nil, []*Node{anonfield(typs[2]), anonfield(typs[2]), anonfield(typs[49])}, []*Node{anonfield(typs[32])})
+	typs[51] = functype(nil, []*Node{anonfield(typs[2]), anonfield(typs[2])}, []*Node{anonfield(typs[32])})
+	typs[52] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[2])}, []*Node{anonfield(typs[2])})
+	typs[53] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3])}, []*Node{anonfield(typs[2])})
+	typs[54] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[2])}, []*Node{anonfield(typs[2]), anonfield(typs[11])})
+	typs[55] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[1]), anonfield(typs[1])}, nil)
+	typs[56] = functype(nil, []*Node{anonfield(typs[1])}, nil)
+	typs[57] = functype(nil, []*Node{anonfield(typs[2]), anonfield(typs[2])}, []*Node{anonfield(typs[11])})
+	typs[58] = typMap(typs[2], typs[2])
+	typs[59] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[15]), anonfield(typs[3]), anonfield(typs[3])}, []*Node{anonfield(typs[58])})
+	typs[60] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[58]), anonfield(typs[3])}, []*Node{anonfield(typs[3])})
+	typs[61] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[58]), anonfield(typs[2])}, []*Node{anonfield(typs[3])})
+	typs[62] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[58]), anonfield(typs[3]), anonfield(typs[1])}, []*Node{anonfield(typs[3])})
+	typs[63] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[58]), anonfield(typs[3])}, []*Node{anonfield(typs[3]), anonfield(typs[11])})
+	typs[64] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[58]), anonfield(typs[2])}, []*Node{anonfield(typs[3]), anonfield(typs[11])})
+	typs[65] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[58]), anonfield(typs[3]), anonfield(typs[1])}, []*Node{anonfield(typs[3]), anonfield(typs[11])})
+	typs[66] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[58]), anonfield(typs[3])}, nil)
+	typs[67] = functype(nil, []*Node{anonfield(typs[3])}, nil)
+	typs[68] = typChan(typs[2], Cboth)
+	typs[69] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[15])}, []*Node{anonfield(typs[68])})
+	typs[70] = typChan(typs[2], Crecv)
+	typs[71] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[70]), anonfield(typs[3])}, nil)
+	typs[72] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[70]), anonfield(typs[3])}, []*Node{anonfield(typs[11])})
+	typs[73] = typChan(typs[2], Csend)
+	typs[74] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[73]), anonfield(typs[3])}, nil)
+	typs[75] = tostruct([]*Node{namedfield("enabled", typs[11]), namedfield("needed", typs[11]), namedfield("cgo", typs[11])})
+	typs[76] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[2])}, nil)
+	typs[77] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3]), anonfield(typs[3])}, nil)
+	typs[78] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3])}, nil)
+	typs[79] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[2]), anonfield(typs[2])}, []*Node{anonfield(typs[32])})
+	typs[80] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[73]), anonfield(typs[3])}, []*Node{anonfield(typs[11])})
+	typs[81] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3]), anonfield(typs[70])}, []*Node{anonfield(typs[11])})
+	typs[82] = typPtr(typs[11])
+	typs[83] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[3]), anonfield(typs[82]), anonfield(typs[70])}, []*Node{anonfield(typs[11])})
+	typs[84] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[15]), anonfield(typs[8])}, nil)
+	typs[85] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[70]), anonfield(typs[3]), anonfield(typs[82])}, []*Node{anonfield(typs[11])})
+	typs[86] = functype(nil, []*Node{anonfield(typs[1])}, []*Node{anonfield(typs[11])})
+	typs[87] = typSlice(typs[2])
+	typs[88] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[32]), anonfield(typs[32])}, []*Node{anonfield(typs[87])})
+	typs[89] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[15]), anonfield(typs[15])}, []*Node{anonfield(typs[87])})
+	typs[90] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[87]), anonfield(typs[32])}, []*Node{anonfield(typs[87])})
+	typs[91] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[3]), anonfield(typs[49])}, nil)
+	typs[92] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[49])}, nil)
+	typs[93] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[3]), anonfield(typs[49])}, []*Node{anonfield(typs[11])})
+	typs[94] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[3])}, []*Node{anonfield(typs[11])})
+	typs[95] = functype(nil, []*Node{anonfield(typs[15]), anonfield(typs[15])}, []*Node{anonfield(typs[15])})
 	typs[96] = functype(nil, []*Node{anonfield(typs[17]), anonfield(typs[17])}, []*Node{anonfield(typs[17])})
-	typs[97] = functype(nil, []*Node{anonfield(typs[19]), anonfield(typs[19])}, []*Node{anonfield(typs[19])})
-	typs[98] = functype(nil, []*Node{anonfield(typs[15])}, []*Node{anonfield(typs[17])})
-	typs[99] = functype(nil, []*Node{anonfield(typs[15])}, []*Node{anonfield(typs[19])})
-	typs[100] = Types[TUINT32]
-	typs[101] = functype(nil, []*Node{anonfield(typs[15])}, []*Node{anonfield(typs[100])})
-	typs[102] = functype(nil, []*Node{anonfield(typs[17])}, []*Node{anonfield(typs[15])})
-	typs[103] = functype(nil, []*Node{anonfield(typs[19])}, []*Node{anonfield(typs[15])})
-	typs[104] = functype(nil, []*Node{anonfield(typs[100])}, []*Node{anonfield(typs[15])})
-	typs[105] = functype(nil, []*Node{anonfield(typs[21]), anonfield(typs[21])}, []*Node{anonfield(typs[21])})
-	typs[106] = functype(nil, []*Node{anonfield(typs[50])}, nil)
-	typs[107] = functype(nil, []*Node{anonfield(typs[50]), anonfield(typs[50])}, nil)
+	typs[97] = functype(nil, []*Node{anonfield(typs[13])}, []*Node{anonfield(typs[15])})
+	typs[98] = functype(nil, []*Node{anonfield(typs[13])}, []*Node{anonfield(typs[17])})
+	typs[99] = Types[TUINT32]
+	typs[100] = functype(nil, []*Node{anonfield(typs[13])}, []*Node{anonfield(typs[99])})
+	typs[101] = functype(nil, []*Node{anonfield(typs[15])}, []*Node{anonfield(typs[13])})
+	typs[102] = functype(nil, []*Node{anonfield(typs[17])}, []*Node{anonfield(typs[13])})
+	typs[103] = functype(nil, []*Node{anonfield(typs[99])}, []*Node{anonfield(typs[13])})
+	typs[104] = functype(nil, []*Node{anonfield(typs[19]), anonfield(typs[19])}, []*Node{anonfield(typs[19])})
+	typs[105] = functype(nil, []*Node{anonfield(typs[49])}, nil)
+	typs[106] = functype(nil, []*Node{anonfield(typs[49]), anonfield(typs[49])}, nil)
 	return typs[:]
 }
diff --git a/src/cmd/compile/internal/gc/builtin/runtime.go b/src/cmd/compile/internal/gc/builtin/runtime.go
index 69511155f4..e9d41a3095 100644
--- a/src/cmd/compile/internal/gc/builtin/runtime.go
+++ b/src/cmd/compile/internal/gc/builtin/runtime.go
@@ -17,7 +17,7 @@ func panicindex()
 func panicslice()
 func panicdivide()
 func throwinit()
-func panicwrap(string, string, string)
+func panicwrap()
 
 func gopanic(interface{})
 func gorecover(*int32) interface{}
diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index 9dd2adcd4c..c7b81858cc 100644
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -1759,22 +1759,8 @@ func genwrapper(rcvr *Type, method *Field, newnam *Sym, iface int) {
 	if rcvr.IsPtr() && rcvr.Elem() == methodrcvr {
 		// generating wrapper from *T to T.
 		n := nod(OIF, nil, nil)
-
 		n.Left = nod(OEQ, this.Left, nodnil())
-
-		// these strings are already in the reflect tables,
-		// so no space cost to use them here.
-		var l []*Node
-
-		var v Val
-		v.U = rcvr.Elem().Sym.Pkg.Name // package name
-		l = append(l, nodlit(v))
-		v.U = rcvr.Elem().Sym.Name // type name
-		l = append(l, nodlit(v))
-		v.U = method.Sym.Name
-		l = append(l, nodlit(v)) // method name
 		call := nod(OCALL, syslook("panicwrap"), nil)
-		call.List.Set(l)
 		n.Nbody.Set1(call)
 		fn.Nbody.Append(n)
 	}
diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index ec73bb3327..7b644cb6b1 100644
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -953,7 +953,7 @@ func isZeroArgRuntimeCall(s *obj.LSym) bool {
 		return false
 	}
 	switch s.Name {
-	case "runtime.panicindex", "runtime.panicslice", "runtime.panicdivide":
+	case "runtime.panicindex", "runtime.panicslice", "runtime.panicdivide", "runtime.panicwrap":
 		return true
 	}
 	return false
diff --git a/src/runtime/error.go b/src/runtime/error.go
index 0238c5e592..f5b015c091 100644
--- a/src/runtime/error.go
+++ b/src/runtime/error.go
@@ -4,6 +4,8 @@
 
 package runtime
 
+import _ "unsafe" // for go:linkname
+
 // The Error interface identifies a run time error.
 type Error interface {
 	error
@@ -91,7 +93,41 @@ func printany(i interface{}) {
 	}
 }
 
+// strings.IndexByte is implemented in runtime/asm_$goarch.s
+// but amusingly we need go:linkname to get access to it here in the runtime.
+//go:linkname stringsIndexByte strings.IndexByte
+func stringsIndexByte(s string, c byte) int
+
 // called from generated code
-func panicwrap(pkg, typ, meth string) {
+func panicwrap() {
+	pc := make([]uintptr, 1)
+	n := Callers(2, pc)
+	if n == 0 {
+		throw("panicwrap: Callers failed")
+	}
+	frames := CallersFrames(pc)
+	frame, _ := frames.Next()
+	name := frame.Function
+	// name is something like "main.(*T).F".
+	// We want to extract pkg ("main"), typ ("T"), and meth ("F").
+	// Do it by finding the parens.
+	i := stringsIndexByte(name, '(')
+	if i < 0 {
+		throw("panicwrap: no ( in " + frame.Function)
+	}
+	pkg := name[:i-1]
+	if i+2 >= len(name) || name[i-1:i+2] != ".(*" {
+		throw("panicwrap: unexpected string after package name: " + frame.Function)
+	}
+	name = name[i+2:]
+	i = stringsIndexByte(name, ')')
+	if i < 0 {
+		throw("panicwrap: no ) in " + frame.Function)
+	}
+	if i+2 >= len(name) || name[i:i+2] != ")." {
+		throw("panicwrap: unexpected string after type name: " + frame.Function)
+	}
+	typ := name[:i]
+	meth := name[i+2:]
 	panic(plainError("value method " + pkg + "." + typ + "." + meth + " called using nil *" + typ + " pointer"))
 }
diff --git a/test/fixedbugs/issue19040.go b/test/fixedbugs/issue19040.go
new file mode 100644
index 0000000000..67881df624
--- /dev/null
+++ b/test/fixedbugs/issue19040.go
@@ -0,0 +1,36 @@
+// run
+
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Check the text of the panic that comes from
+// a nil pointer passed to automatically generated method wrapper.
+
+package main
+
+import "fmt"
+
+type T int
+
+type I interface {
+	F()
+}
+
+func (t T) F() {}
+
+var (
+	t *T
+	i I = t
+)
+
+func main() {
+	defer func() {
+		got := recover().(error).Error()
+		want := "value method main.T.F called using nil *T pointer"
+		if got != want {
+			fmt.Printf("panicwrap error text:\n\t%q\nwant:\n\t%q\n", got, want)
+		}
+	}()
+	i.F()
+}