[dev.ssa] cmd/compile: use function calls instead of special ops for panics

There's no need for special ops for panicindex and panicslice.
Just use regular runtime calls.

Change-Id: I71b9b73f4f1ebce1220fdc1e7b7f65cfcf4b7bae
Reviewed-on: https://go-review.googlesource.com/14726Reviewed-by: David Chase <drchase@google.com>

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

@@ -2312,7 +2312,7 @@ func (s *state) boundsCheck(idx, len *ssa.Value) {
 
 	// bounds check
 	cmp := s.newValue2(ssa.OpIsInBounds, Types[TBOOL], idx, len)
-	s.check(cmp, ssa.OpPanicIndexCheck)
+	s.check(cmp, Panicindex)
 }
 
 // sliceBoundsCheck generates slice bounds checking code.  Checks if 0 <= idx <= len, branches to exit if not.
@@ -2326,11 +2326,11 @@ func (s *state) sliceBoundsCheck(idx, len *ssa.Value) {
 
 	// bounds check
 	cmp := s.newValue2(ssa.OpIsSliceInBounds, Types[TBOOL], idx, len)
-	s.check(cmp, ssa.OpPanicSliceCheck)
+	s.check(cmp, panicslice)
 }
 
-// If cmp (a bool) is true, panic using the given op.
-func (s *state) check(cmp *ssa.Value, panicOp ssa.Op) {
+// If cmp (a bool) is true, panic using the given function.
+func (s *state) check(cmp *ssa.Value, fn *Node) {
 	b := s.endBlock()
 	b.Kind = ssa.BlockIf
 	b.Control = cmp
@@ -2340,12 +2340,10 @@ func (s *state) check(cmp *ssa.Value, panicOp ssa.Op) {
 	b.AddEdgeTo(bNext)
 	b.AddEdgeTo(bPanic)
 	s.startBlock(bPanic)
-	// The panic check takes/returns memory to ensure that the right
+	// The panic call takes/returns memory to ensure that the right
 	// memory state is observed if the panic happens.
-	chk := s.newValue1(panicOp, ssa.TypeMem, s.mem())
-	s.endBlock()
-	bPanic.Kind = ssa.BlockExit
-	bPanic.Control = chk
+	s.rtcall(fn, false, nil)
+
 	s.startBlock(bNext)
 }
 
@@ -3700,16 +3698,6 @@ func (s *genState) genValue(v *ssa.Value) {
 		q.From.Reg = x86.REG_AX
 		q.To.Type = obj.TYPE_MEM
 		q.To.Reg = r
-	case ssa.OpAMD64LoweredPanicIndexCheck:
-		p := Prog(obj.ACALL)
-		p.To.Type = obj.TYPE_MEM
-		p.To.Name = obj.NAME_EXTERN
-		p.To.Sym = Linksym(Panicindex.Sym)
-	case ssa.OpAMD64LoweredPanicSliceCheck:
-		p := Prog(obj.ACALL)
-		p.To.Type = obj.TYPE_MEM
-		p.To.Name = obj.NAME_EXTERN
-		p.To.Sym = Linksym(panicslice.Sym)
 	case ssa.OpAMD64LoweredGetG:
 		r := regnum(v)
 		// See the comments in cmd/internal/obj/x86/obj6.go

src/cmd/compile/internal/ssa/gen/AMD64.rules

@@ -287,8 +287,6 @@
 (IsSliceInBounds idx len) -> (SETBE (CMPQ idx len))
 
 (PanicNilCheck ptr mem) -> (LoweredPanicNilCheck ptr mem)
-(PanicIndexCheck mem) -> (LoweredPanicIndexCheck mem)
-(PanicSliceCheck mem) -> (LoweredPanicSliceCheck mem)
 (GetG) -> (LoweredGetG)
 
 (Move [size] dst src mem) -> (REPMOVSB dst src (MOVQconst <config.Frontend().TypeUInt64()> [size]) mem)

src/cmd/compile/internal/ssa/gen/AMD64Ops.go

@@ -403,8 +403,6 @@ func init() {
 
 		// Pseudo-ops
 		{name: "LoweredPanicNilCheck", reg: gp10},
-		{name: "LoweredPanicIndexCheck"},
-		{name: "LoweredPanicSliceCheck"},
 		{name: "LoweredGetG", reg: gp01},
 	}
 

src/cmd/compile/internal/ssa/gen/genericOps.go

@@ -325,10 +325,8 @@ var genericOps = []opData{
 	{name: "IsSliceInBounds", typ: "Bool"}, // 0 <= arg0 <= arg1
 
 	// Pseudo-ops
-	{name: "PanicNilCheck"},   // trigger a dereference fault; arg0=nil ptr, arg1=mem, returns mem
-	{name: "PanicIndexCheck"}, // trigger a bounds check failure, arg0=mem, returns mem
-	{name: "PanicSliceCheck"}, // trigger a slice bounds check failure, arg0=mem, returns mem
-	{name: "GetG"},            // runtime.getg() (read g pointer)
+	{name: "PanicNilCheck"}, // trigger a dereference fault; arg0=nil ptr, arg1=mem, returns mem
+	{name: "GetG"},          // runtime.getg() (read g pointer)
 
 	// Indexing operations
 	{name: "ArrayIndex"},   // arg0=array, arg1=index.  Returns a[i]

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

@@ -270,8 +270,6 @@ const (
 	OpAMD64REPMOVSB
 	OpAMD64InvertFlags
 	OpAMD64LoweredPanicNilCheck
-	OpAMD64LoweredPanicIndexCheck
-	OpAMD64LoweredPanicSliceCheck
 	OpAMD64LoweredGetG
 
 	OpAdd8
@@ -513,8 +511,6 @@ const (
 	OpIsInBounds
 	OpIsSliceInBounds
 	OpPanicNilCheck
-	OpPanicIndexCheck
-	OpPanicSliceCheck
 	OpGetG
 	OpArrayIndex
 	OpPtrIndex
@@ -3115,14 +3111,6 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
-	{
-		name: "LoweredPanicIndexCheck",
-		reg:  regInfo{},
-	},
-	{
-		name: "LoweredPanicSliceCheck",
-		reg:  regInfo{},
-	},
 	{
 		name: "LoweredGetG",
 		reg: regInfo{
@@ -4088,14 +4076,6 @@ var opcodeTable = [...]opInfo{
 		name:    "PanicNilCheck",
 		generic: true,
 	},
-	{
-		name:    "PanicIndexCheck",
-		generic: true,
-	},
-	{
-		name:    "PanicSliceCheck",
-		generic: true,
-	},
 	{
 		name:    "GetG",
 		generic: true,

src/cmd/compile/internal/ssa/rewriteAMD64.go

@@ -6905,22 +6905,6 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
 		goto end6f8a8c559a167d1f0a5901d09a1fb248
 	end6f8a8c559a167d1f0a5901d09a1fb248:
 		;
-	case OpPanicIndexCheck:
-		// match: (PanicIndexCheck mem)
-		// cond:
-		// result: (LoweredPanicIndexCheck mem)
-		{
-			mem := v.Args[0]
-			v.Op = OpAMD64LoweredPanicIndexCheck
-			v.AuxInt = 0
-			v.Aux = nil
-			v.resetArgs()
-			v.AddArg(mem)
-			return true
-		}
-		goto enda5014ba73d3550a5b66424044395c70f
-	enda5014ba73d3550a5b66424044395c70f:
-		;
 	case OpPanicNilCheck:
 		// match: (PanicNilCheck ptr mem)
 		// cond:
@@ -6939,22 +6923,6 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
 		goto enda02b1ad5a6f929b782190145f2c8628b
 	enda02b1ad5a6f929b782190145f2c8628b:
 		;
-	case OpPanicSliceCheck:
-		// match: (PanicSliceCheck mem)
-		// cond:
-		// result: (LoweredPanicSliceCheck mem)
-		{
-			mem := v.Args[0]
-			v.Op = OpAMD64LoweredPanicSliceCheck
-			v.AuxInt = 0
-			v.Aux = nil
-			v.resetArgs()
-			v.AddArg(mem)
-			return true
-		}
-		goto end238ed0074810b55bd2bba7b45cdeed68
-	end238ed0074810b55bd2bba7b45cdeed68:
-		;
 	case OpRsh16Ux16:
 		// match: (Rsh16Ux16 <t> x y)
 		// cond: