cmd/internal/gc: separate func-only Node fields
Nodes dominate gc's memory usage, but many fields are only used
for a subset of kinds of nodes. This change pulls out fields
used only for func-like Nodes. This reduces the size of the
Node struct on a 64-bit machine from 504 bytes to 416 bytes (-17%).
Compiling the runtime, 1.5% of nodes have a non-nil Func.
In html/template, 2.7% of nodes have a non-nil Func.
This change introduces an extra alloc and associated GC overhead
when Func is non-nil. However, when Func is nil, as it almost
always is, it spares the garbage collector scanning some Node fields.
Empirically, this change appears to be roughly neutral with regard to GC.
To keep the diff readable, this CL uses an embedded Func field.
A subsequent CL will unembed the field.
Passes toolstash -cmp.
Change-Id: Ide86aa954b097fb8e6154f0811d3691497477004
Reviewed-on: https://go-review.googlesource.com/7360
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/internal/gc/syntax.go b/src/cmd/internal/gc/syntax.go
index 1c84aa1..593e81e 100644
--- a/src/cmd/internal/gc/syntax.go
+++ b/src/cmd/internal/gc/syntax.go
@@ -23,58 +23,45 @@
List *NodeList
Rlist *NodeList
- Op uint8
- Nointerface bool
- Ullman uint8 // sethi/ullman number
- Addable uint8 // type of addressability - 0 is not addressable
- Etype uint8 // op for OASOP, etype for OTYPE, exclam for export
- Bounded bool // bounds check unnecessary
- Class uint8 // PPARAM, PAUTO, PEXTERN, etc
- Method uint8 // OCALLMETH name
- Embedded uint8 // ODCLFIELD embedded type
- Colas uint8 // OAS resulting from :=
- Diag uint8 // already printed error about this
- Noescape bool // func arguments do not escape
- Nosplit bool // func should not execute on separate stack
- Nowritebarrier bool // emit compiler error instead of write barrier
- Walkdef uint8
- Typecheck uint8
- Local bool
- Dodata uint8
- Initorder uint8
- Used bool
- Isddd bool // is the argument variadic
- Readonly bool
- Implicit bool
- Addrtaken bool // address taken, even if not moved to heap
- Assigned bool // is the variable ever assigned to
- Captured bool // is the variable captured by a closure
- Byval bool // is the variable captured by value or by reference
- Dupok bool // duplicate definitions ok (for func)
- Wrapper bool // is method wrapper (for func)
- Reslice bool // this is a reslice x = x[0:y] or x = append(x, ...)
- Likely int8 // likeliness of if statement
- Hasbreak bool // has break statement
- Needzero bool // if it contains pointers, needs to be zeroed on function entry
- Needctxt bool // function uses context register (has closure variables)
- Esc uint8 // EscXXX
- Funcdepth int32
+ Op uint8
+ Nointerface bool
+ Ullman uint8 // sethi/ullman number
+ Addable uint8 // type of addressability - 0 is not addressable
+ Etype uint8 // op for OASOP, etype for OTYPE, exclam for export
+ Bounded bool // bounds check unnecessary
+ Class uint8 // PPARAM, PAUTO, PEXTERN, etc
+ Method uint8 // OCALLMETH name
+ Embedded uint8 // ODCLFIELD embedded type
+ Colas uint8 // OAS resulting from :=
+ Diag uint8 // already printed error about this
+ Noescape bool // func arguments do not escape; TODO(rsc): move Noescape to Func struct (see CL 7360)
+ Walkdef uint8
+ Typecheck uint8
+ Local bool
+ Dodata uint8
+ Initorder uint8
+ Used bool
+ Isddd bool // is the argument variadic
+ Readonly bool
+ Implicit bool
+ Addrtaken bool // address taken, even if not moved to heap
+ Assigned bool // is the variable ever assigned to
+ Captured bool // is the variable captured by a closure
+ Byval bool // is the variable captured by value or by reference
+ Reslice bool // this is a reslice x = x[0:y] or x = append(x, ...)
+ Likely int8 // likeliness of if statement
+ Hasbreak bool // has break statement
+ Needzero bool // if it contains pointers, needs to be zeroed on function entry
+ Esc uint8 // EscXXX
+ Funcdepth int32
// most nodes
- Type *Type
- Orig *Node // original form, for printing, and tracking copies of ONAMEs
+ Type *Type
+ Orig *Node // original form, for printing, and tracking copies of ONAMEs
+ Nname *Node
// func
- Nname *Node
- Shortname *Node
- Enter *NodeList
- Exit *NodeList
- Cvars *NodeList // closure params
- Dcl *NodeList // autodcl for this func/closure
- Inl *NodeList // copy of the body for use in inlining
- Inldcl *NodeList // copy of dcl for use in inlining
- Closgen int
- Outerfunc *Node
+ *Func
// OLITERAL/OREGISTER
Val Val
@@ -112,18 +99,39 @@
Escretval *NodeList // on OCALLxxx, list of dummy return values
Escloopdepth int // -1: global, 0: return variables, 1:function top level, increased inside function for every loop or label to mark scopes
- Sym *Sym // various
- InlCost int32 // unique name for OTYPE/ONAME
- Vargen int32
- Lineno int32
+ Sym *Sym // various
+ Vargen int32 // unique name for OTYPE/ONAME
+ Lineno int32
+ Xoffset int64
+ Stkdelta int64 // offset added by stack frame compaction phase.
+ Ostk int32 // 6g only
+ Iota int32
+ Walkgen uint32
+ Esclevel int32
+ Opt interface{} // for optimization passes
+}
+
+// Func holds Node fields used only with function-like nodes.
+type Func struct {
+ Shortname *Node
+ Enter *NodeList
+ Exit *NodeList
+ Cvars *NodeList // closure params
+ Dcl *NodeList // autodcl for this func/closure
+ Inldcl *NodeList // copy of dcl for use in inlining
+ Closgen int
+ Outerfunc *Node
+
+ Inl *NodeList // copy of the body for use in inlining
+ InlCost int32
+
Endlineno int32
- Xoffset int64
- Stkdelta int64 // offset added by stack frame compaction phase.
- Ostk int32
- Iota int32
- Walkgen uint32
- Esclevel int32
- Opt interface{} // for optimization passes
+
+ Nosplit bool // func should not execute on separate stack
+ Nowritebarrier bool // emit compiler error instead of write barrier
+ Dupok bool // duplicate definitions ok
+ Wrapper bool // is method wrapper
+ Needctxt bool // function uses context register (has closure variables)
}
// Node ops.
