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cmd/compile: remove duplicate nilchecks

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Mark nil check operations as faulting if their arg is zero.
This lets the late nilcheck pass remove duplicates.

Fixes #17242.

Change-Id: I4c9938d8a5a1e43edd85b4a66f0b34004860bcd9
Reviewed-on: https://go-review.googlesource.com/29952
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Keith Randall 2016-09-27 14:39:27 -07:00
parent ba94dd3438
commit 98938189a1
9 changed files with 53 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/cmd/compile/internal/ssa/gen/386Ops.go
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@ -439,7 +439,7 @@ func init() {
// use of DX (the closure pointer)
{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("DX")}}},
//arg0=ptr,arg1=mem, returns void. Faults if ptr is nil.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpsp}}, clobberFlags: true, nilCheck: true},
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpsp}}, clobberFlags: true, nilCheck: true, faultOnNilArg0: true},
// MOVLconvert converts between pointers and integers.
// We have a special op for this so as to not confuse GC

2
src/cmd/compile/internal/ssa/gen/AMD64Ops.go
View File

@ -486,7 +486,7 @@ func init() {
// use of DX (the closure pointer)
{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("DX")}}},
//arg0=ptr,arg1=mem, returns void. Faults if ptr is nil.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpsp}}, clobberFlags: true, nilCheck: true},
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpsp}}, clobberFlags: true, nilCheck: true, faultOnNilArg0: true},
// MOVQconvert converts between pointers and integers.
// We have a special op for this so as to not confuse GC

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

@ -325,7 +325,7 @@ func init() {
{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
// pseudo-ops
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true}, // panic if arg0 is nil. arg1=mem.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true, faultOnNilArg0: true}, // panic if arg0 is nil. arg1=mem.
{name: "Equal", argLength: 1, reg: readflags}, // bool, true flags encode x==y false otherwise.
{name: "NotEqual", argLength: 1, reg: readflags}, // bool, true flags encode x!=y false otherwise.

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

@ -381,7 +381,7 @@ func init() {
{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
// pseudo-ops
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true}, // panic if arg0 is nil. arg1=mem.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true, faultOnNilArg0: true}, // panic if arg0 is nil. arg1=mem.
{name: "Equal", argLength: 1, reg: readflags}, // bool, true flags encode x==y false otherwise.
{name: "NotEqual", argLength: 1, reg: readflags}, // bool, true flags encode x!=y false otherwise.

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

@ -336,7 +336,7 @@ func init() {
},
// pseudo-ops
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true}, // panic if arg0 is nil. arg1=mem.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true, faultOnNilArg0: true}, // panic if arg0 is nil. arg1=mem.
{name: "FPFlagTrue", argLength: 1, reg: readflags}, // bool, true if FP flag is true
{name: "FPFlagFalse", argLength: 1, reg: readflags}, // bool, true if FP flag is false

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

@ -288,7 +288,7 @@ func init() {
{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{ctxt}}},
//arg0=ptr,arg1=mem, returns void. Faults if ptr is nil.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gp | sp | sb}, clobbers: tmp}, clobberFlags: true, nilCheck: true},
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gp | sp | sb}, clobbers: tmp}, clobberFlags: true, nilCheck: true, faultOnNilArg0: true},
// Convert pointer to integer, takes a memory operand for ordering.
{name: "MOVDconvert", argLength: 2, reg: gp11, asm: "MOVD"},

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

@ -370,7 +370,7 @@ func init() {
// use of R12 (the closure pointer)
{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R12")}}},
// arg0=ptr,arg1=mem, returns void. Faults if ptr is nil.
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{ptrsp}}, clobberFlags: true, nilCheck: true},
{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{ptrsp}}, clobberFlags: true, nilCheck: true, faultOnNilArg0: true},
// MOVDconvert converts between pointers and integers.
// We have a special op for this so as to not confuse GC

57
src/cmd/compile/internal/ssa/opGen.go
View File

@ -4023,10 +4023,11 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "LoweredNilCheck",
argLen: 2,
clobberFlags: true,
nilCheck: true,
name: "LoweredNilCheck",
argLen: 2,
clobberFlags: true,
nilCheck: true,
faultOnNilArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 255}, // AX CX DX BX SP BP SI DI
@ -6992,10 +6993,11 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "LoweredNilCheck",
argLen: 2,
clobberFlags: true,
nilCheck: true,
name: "LoweredNilCheck",
argLen: 2,
clobberFlags: true,
nilCheck: true,
faultOnNilArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 65535}, // AX CX DX BX SP BP SI DI R8 R9 R10 R11 R12 R13 R14 R15
@ -10081,9 +10083,10 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "LoweredNilCheck",
argLen: 2,
nilCheck: true,
name: "LoweredNilCheck",
argLen: 2,
nilCheck: true,
faultOnNilArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 6143}, // R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 g R12
@ -12200,9 +12203,10 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "LoweredNilCheck",
argLen: 2,
nilCheck: true,
name: "LoweredNilCheck",
argLen: 2,
nilCheck: true,
faultOnNilArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 268173311}, // 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
@ -13817,9 +13821,10 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "LoweredNilCheck",
argLen: 2,
nilCheck: true,
name: "LoweredNilCheck",
argLen: 2,
nilCheck: true,
faultOnNilArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 100663294}, // 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
@ -15195,10 +15200,11 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "LoweredNilCheck",
argLen: 2,
clobberFlags: true,
nilCheck: true,
name: "LoweredNilCheck",
argLen: 2,
clobberFlags: true,
nilCheck: true,
faultOnNilArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 1073733630}, // SP SB 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
@ -17511,10 +17517,11 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "LoweredNilCheck",
argLen: 2,
clobberFlags: true,
nilCheck: true,
name: "LoweredNilCheck",
argLen: 2,
clobberFlags: true,
nilCheck: true,
faultOnNilArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 37886}, // R1 R2 R3 R4 R5 R6 R7 R8 R9 R12 SP

14
test/nilptr3.go
View File

@ -233,3 +233,17 @@ func c1() {
var x Struct
func() { x.m() }() // ERROR "removed nil check"
}
type SS struct {
x byte
}
type TT struct {
SS
}
func f(t *TT) *byte {
// See issue 17242.
s := &t.SS // ERROR "removed nil check"
return &s.x // ERROR "generated nil check"
}