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cmd/compile: don't clobber LR for tail calls

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When doing a tail call the link register is live as the callee
will directly return to the caller (of the function that does the
tail call). Don't allocate or clobber the link register.

Fixes #49032.

Change-Id: I2d60f2354e5b6c14aa285c8983a9786687b90223
Reviewed-on: https://go-review.googlesource.com/c/go/+/358435
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
This commit is contained in:
Cherry Mui 2021-10-25 11:51:25 -04:00
parent 95372efc4d
commit 9012996a9a
14 changed files with 40 additions and 22 deletions
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2
src/cmd/compile/internal/ssa/gen/386Ops.go
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@ -455,7 +455,7 @@ func init() {
},
{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("DX"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem

2
src/cmd/compile/internal/ssa/gen/AMD64Ops.go
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@ -765,7 +765,7 @@ func init() {
// With a register ABI, the actual register info for these instructions (i.e., what is used in regalloc) is augmented with per-call-site bindings of additional arguments to specific in and out registers.
{name: "CALLstatic", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call static function aux.(*obj.LSym). last arg=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // tail call static function aux.(*obj.LSym). last arg=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). last arg=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: -1, reg: regInfo{inputs: []regMask{gpsp, buildReg("DX"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure. arg0=codeptr, arg1=closure, last arg=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: -1, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, last arg=mem, auxint=argsize, returns mem

2
src/cmd/compile/internal/ssa/gen/ARM64Ops.go
View File

@ -492,7 +492,7 @@ func init() {
// function calls
{name: "CALLstatic", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call static function aux.(*obj.LSym). last arg=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // tail call static function aux.(*obj.LSym). last arg=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). last arg=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: -1, reg: regInfo{inputs: []regMask{gpsp, buildReg("R26"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure. arg0=codeptr, arg1=closure, last arg=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: -1, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, last arg=mem, auxint=argsize, returns mem

2
src/cmd/compile/internal/ssa/gen/ARMOps.go
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@ -432,7 +432,7 @@ func init() {
// function calls
{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R7"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem

2
src/cmd/compile/internal/ssa/gen/MIPS64Ops.go
View File

@ -276,7 +276,7 @@ func init() {
// function calls
{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R22"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem

2
src/cmd/compile/internal/ssa/gen/MIPSOps.go
View File

@ -258,7 +258,7 @@ func init() {
// function calls
{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R22"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem

2
src/cmd/compile/internal/ssa/gen/PPC64Ops.go
View File

@ -434,7 +434,7 @@ func init() {
{name: "LoweredRound64F", argLength: 1, reg: fp11, resultInArg0: true, zeroWidth: true},
{name: "CALLstatic", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: -1, reg: regInfo{inputs: []regMask{callptr, ctxt, 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: -1, reg: regInfo{inputs: []regMask{callptr}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem

8
src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
View File

@ -240,10 +240,10 @@ func init() {
{name: "MOVconvert", argLength: 2, reg: gp11, asm: "MOV"}, // arg0, but converted to int/ptr as appropriate; arg1=mem
// Calls
{name: "CALLstatic", argLength: 1, reg: call, aux: "CallOff", call: true}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: call, aux: "CallOff", call: true}, // tail call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: callClosure, aux: "CallOff", call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: 2, reg: callInter, aux: "CallOff", call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
{name: "CALLstatic", argLength: 1, reg: call, aux: "CallOff", call: true}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: call, aux: "CallOff", call: true, tailCall: true}, // tail call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: callClosure, aux: "CallOff", call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: 2, reg: callInter, aux: "CallOff", call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
// duffzero
// arg0 = address of memory to zero (in X10, changed as side effect)

2
src/cmd/compile/internal/ssa/gen/S390XOps.go
View File

@ -480,7 +480,7 @@ func init() {
{name: "CLEAR", argLength: 2, reg: regInfo{inputs: []regMask{ptr, 0}}, asm: "CLEAR", aux: "SymValAndOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true, symEffect: "Write"},
{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{ptrsp, buildReg("R12"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{ptr}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem

2
src/cmd/compile/internal/ssa/gen/WasmOps.go
View File

@ -124,7 +124,7 @@ func init() {
var WasmOps = []opData{
{name: "LoweredStaticCall", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", call: true}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "LoweredTailCall", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", call: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "LoweredTailCall", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", call: true, tailCall: true}, // tail call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "LoweredClosureCall", argLength: 3, reg: regInfo{inputs: []regMask{gp, gp, 0}, clobbers: callerSave}, aux: "CallOff", call: true}, // call function via closure. arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
{name: "LoweredInterCall", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem

5
src/cmd/compile/internal/ssa/gen/main.go
View File

@ -63,6 +63,7 @@ type opData struct {
resultNotInArgs bool // outputs must not be allocated to the same registers as inputs
clobberFlags bool // this op clobbers flags register
call bool // is a function call
tailCall bool // is a tail call
nilCheck bool // this op is a nil check on arg0
faultOnNilArg0 bool // this op will fault if arg0 is nil (and aux encodes a small offset)
faultOnNilArg1 bool // this op will fault if arg1 is nil (and aux encodes a small offset)
@ -307,6 +308,9 @@ func genOp() {
if v.call {
fmt.Fprintln(w, "call: true,")
}
if v.tailCall {
fmt.Fprintln(w, "tailCall: true,")
}
if v.nilCheck {
fmt.Fprintln(w, "nilCheck: true,")
}
@ -405,6 +409,7 @@ func genOp() {
fmt.Fprintln(w, "func (o Op) SymEffect() SymEffect { return opcodeTable[o].symEffect }")
fmt.Fprintln(w, "func (o Op) IsCall() bool { return opcodeTable[o].call }")
fmt.Fprintln(w, "func (o Op) IsTailCall() bool { return opcodeTable[o].tailCall }")
fmt.Fprintln(w, "func (o Op) HasSideEffects() bool { return opcodeTable[o].hasSideEffects }")
fmt.Fprintln(w, "func (o Op) UnsafePoint() bool { return opcodeTable[o].unsafePoint }")
fmt.Fprintln(w, "func (o Op) ResultInArg0() bool { return opcodeTable[o].resultInArg0 }")

1
src/cmd/compile/internal/ssa/op.go
View File

@ -34,6 +34,7 @@ type opInfo struct {
resultNotInArgs bool // outputs must not be allocated to the same registers as inputs
clobberFlags bool // this op clobbers flags register
call bool // is a function call
tailCall bool // is a tail call
nilCheck bool // this op is a nil check on arg0
faultOnNilArg0 bool // this op will fault if arg0 is nil (and aux encodes a small offset)
faultOnNilArg1 bool // this op will fault if arg1 is nil (and aux encodes a small offset)

27
src/cmd/compile/internal/ssa/opGen.go
View File

@ -5948,6 +5948,7 @@ var opcodeTable = [...]opInfo{
argLen: 1,
clobberFlags: true,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 65519, // AX CX DX BX BP SI DI X0 X1 X2 X3 X4 X5 X6 X7
},
@ -13153,6 +13154,7 @@ var opcodeTable = [...]opInfo{
argLen: -1,
clobberFlags: true,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 2147483631, // AX CX DX BX BP SI DI R8 R9 R10 R11 R12 R13 g R15 X0 X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14
},
@ -17201,6 +17203,7 @@ var opcodeTable = [...]opInfo{
argLen: 1,
clobberFlags: true,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 4294924287, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 g R12 R14 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15
},
@ -21094,6 +21097,7 @@ var opcodeTable = [...]opInfo{
argLen: -1,
clobberFlags: true,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 9223372035512336383, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R19 R20 R21 R22 R23 R24 R25 R26 g R30 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
},
@ -23045,6 +23049,7 @@ var opcodeTable = [...]opInfo{
argLen: 1,
clobberFlags: true,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 140737421246462, // R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R24 R25 R28 g R31 F0 F2 F4 F6 F8 F10 F12 F14 F16 F18 F20 F22 F24 F26 F28 F30 HI LO
},
@ -24614,6 +24619,7 @@ var opcodeTable = [...]opInfo{
argLen: 1,
clobberFlags: true,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 4611686018393833470, // R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R24 R25 g R31 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31 HI LO
},
@ -27464,6 +27470,7 @@ var opcodeTable = [...]opInfo{
argLen: -1,
clobberFlags: true,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 576460745860964344, // R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 g F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26
},
@ -28875,10 +28882,11 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "CALLtail",
auxType: auxCallOff,
argLen: 1,
call: true,
name: "CALLtail",
auxType: auxCallOff,
argLen: 1,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 9223372035781033972, // X3 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 g X28 X29 X30 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
},
@ -32644,6 +32652,7 @@ var opcodeTable = [...]opInfo{
argLen: 1,
clobberFlags: true,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 4294933503, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R11 R12 g R14 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15
},
@ -33319,10 +33328,11 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "LoweredTailCall",
auxType: auxCallOff,
argLen: 1,
call: true,
name: "LoweredTailCall",
auxType: auxCallOff,
argLen: 1,
call: true,
tailCall: true,
reg: regInfo{
clobbers: 844424930131967, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31 g
},
@ -36890,6 +36900,7 @@ func (o Op) Scale() int16 { return int16(opcodeTable[o].scale) }
func (o Op) String() string { return opcodeTable[o].name }
func (o Op) SymEffect() SymEffect { return opcodeTable[o].symEffect }
func (o Op) IsCall() bool { return opcodeTable[o].call }
func (o Op) IsTailCall() bool { return opcodeTable[o].tailCall }
func (o Op) HasSideEffects() bool { return opcodeTable[o].hasSideEffects }
func (o Op) UnsafePoint() bool { return opcodeTable[o].unsafePoint }
func (o Op) ResultInArg0() bool { return opcodeTable[o].resultInArg0 }

3
src/cmd/compile/internal/ssa/regalloc.go
View File

@ -559,7 +559,8 @@ func (s *regAllocState) allocValToReg(v *Value, mask regMask, nospill bool, pos
func isLeaf(f *Func) bool {
for _, b := range f.Blocks {
for _, v := range b.Values {
if opcodeTable[v.Op].call {
if v.Op.IsCall() && !v.Op.IsTailCall() {
// tail call is not counted as it does not save retur PC or need a frame
return false
}
}