gc/runtime: pass type structure to makeslice.

  * inform garbage collector about memory with no pointers in it

1.9s	gcc reverse-complement.c

reverse-complement.go
4.5s / 3.5s	original, with/without bounds checks
3.5s / 3.3s	bounds check reduction
3.3s / 2.8s	smarter garbage collector
2.6s / 2.3s		assembler bytes.IndexByte
2.5s / 2.1s	even smarter garbage collector (this CL)

R=r
https://golang.org/cl/165064

src/cmd/gc/builtin.c.boot

@@ -64,7 +64,7 @@ char *runtimeimport =
 	"func runtime.selectrecv (sel *uint8, hchan <-chan any, elem *any) (selected bool)\n"
 	"func runtime.selectdefault (sel *uint8) (selected bool)\n"
 	"func runtime.selectgo (sel *uint8)\n"
-	"func runtime.makeslice (nel int, cap int, width int) (ary []any)\n"
+	"func runtime.makeslice (typ *uint8, nel int, cap int) (ary []any)\n"
 	"func runtime.sliceslice1 (old []any, lb int, width int) (ary []any)\n"
 	"func runtime.sliceslice (old []any, lb int, hb int, width int) (ary []any)\n"
 	"func runtime.slicearray (old *any, nel int, lb int, hb int, width int) (ary []any)\n"

src/cmd/gc/reflect.c

@@ -325,6 +325,67 @@ dextratype(Type *t)
 	return s;
 }
 
+enum {
+	KindBool = 1,
+	KindInt,
+	KindInt8,
+	KindInt16,
+	KindInt32,
+	KindInt64,
+	KindUint,
+	KindUint8,
+	KindUint16,
+	KindUint32,
+	KindUint64,
+	KindUintptr,
+	KindFloat,
+	KindFloat32,
+	KindFloat64,
+	KindArray,
+	KindChan,
+	KindDotDotDot,
+	KindFunc,
+	KindInterface,
+	KindMap,
+	KindPtr,
+	KindSlice,
+	KindString,
+	KindStruct,
+	KindUnsafePointer,
+	
+	KindNoPointers = 1<<7,
+};
+
+static int
+kinds[] =
+{
+	[TINT]		= KindInt,
+	[TUINT]		= KindUint,
+	[TINT8]		= KindInt8,
+	[TUINT8]	= KindUint8,
+	[TINT16]	= KindInt16,
+	[TUINT16]	= KindUint16,
+	[TINT32]	= KindInt32,
+	[TUINT32]	= KindUint32,
+	[TINT64]	= KindInt64,
+	[TUINT64]	= KindUint64,
+	[TUINTPTR]	= KindUintptr,
+	[TFLOAT]	= KindFloat,
+	[TFLOAT32]	= KindFloat32,
+	[TFLOAT64]	= KindFloat64,
+	[TBOOL]		= KindBool,
+	[TSTRING]		= KindString,
+	[TDDD]		= KindDotDotDot,
+	[TPTR32]		= KindPtr,
+	[TPTR64]		= KindPtr,
+	[TSTRUCT]	= KindStruct,
+	[TINTER]		= KindInterface,
+	[TCHAN]		= KindChan,
+	[TMAP]		= KindMap,
+	[TARRAY]		= KindArray,
+	[TFUNC]		= KindFunc,
+};
+
 static char*
 structnames[] =
 {
@@ -377,6 +438,50 @@ typestruct(Type *t)
 	return pkglookup(name, "type");
 }
 
+static int
+haspointers(Type *t)
+{
+	Type *t1;
+
+	switch(t->etype) {
+	case TINT:
+	case TUINT:
+	case TINT8:
+	case TUINT8:
+	case TINT16:
+	case TUINT16:
+	case TINT32:
+	case TUINT32:
+	case TINT64:
+	case TUINT64:
+	case TUINTPTR:
+	case TFLOAT:
+	case TFLOAT32:
+	case TFLOAT64:
+	case TBOOL:
+		return 0;
+	case TARRAY:
+		if(t->bound < 0)	// slice
+			return 1;
+		return haspointers(t->type);
+	case TSTRUCT:
+		for(t1=t->type; t1!=T; t1=t1->down)
+			if(haspointers(t1->type))
+				return 1;
+		return 0;
+	case TSTRING:
+	case TDDD:
+	case TPTR32:
+	case TPTR64:
+	case TINTER:
+	case TCHAN:
+	case TMAP:
+	case TFUNC:
+	default:
+		return 1;
+	}
+}
+
 /*
  * commonType
  * ../../pkg/runtime/type.go:/commonType
@@ -421,6 +526,12 @@ dcommontype(Sym *s, int ot, Type *t)
 		i = maxround;
 	ot = duint8(s, ot, i);	// align
 	ot = duint8(s, ot, i);	// fieldAlign
+	i = kinds[t->etype];
+	if(t->etype == TARRAY && t->bound < 0)
+		i = KindSlice;
+	if(!haspointers(t))
+		i |= KindNoPointers;
+	ot = duint8(s, ot, i);
 	p = smprint("%#-T", t);
 	ot = dgostringptr(s, ot, p);	// string
 	free(p);

src/cmd/gc/runtime.go

@@ -79,7 +79,7 @@ func selectrecv(sel *byte, hchan <-chan any, elem *any) (selected bool)
 func selectdefault(sel *byte) (selected bool)
 func selectgo(sel *byte)
 
-func makeslice(nel int, cap int, width int) (ary []any)
+func makeslice(typ *byte, nel int, cap int) (ary []any)
 func sliceslice1(old []any, lb int, width int) (ary []any)
 func sliceslice(old []any, lb int, hb int, width int) (ary []any)
 func slicearray(old *any, nel int, lb int, hb int, width int) (ary []any)

src/cmd/gc/walk.c

@@ -994,9 +994,9 @@ walkexpr(Node **np, NodeList **init)
 		fn = syslook("makeslice", 1);
 		argtype(fn, t->type);			// any-1
 		n = mkcall1(fn, n->type, nil,
+			typename(n->type),
 			conv(n->left, types[TINT]),
-			conv(n->right, types[TINT]),
-			nodintconst(t->type->width));
+			conv(n->right, types[TINT]));
 		goto ret;
 
 	case ORUNESTR:

src/pkg/runtime/slice.c

@@ -3,35 +3,35 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "type.h"
+#include "malloc.h"
 
 static	int32	debug	= 0;
 
-// makeslice(nel int, cap int, width int) (ary []any);
+// makeslice(typ *Type, nel int, cap int) (ary []any);
 void
-runtime·makeslice(uint32 nel, uint32 cap, uint32 width, Slice ret)
+runtime·makeslice(SliceType *t, uint32 nel, uint32 cap, Slice ret)
 {
 	uint64 size;
 
 	if(cap < nel)
 		cap = nel;
-	size = cap*width;
+	size = cap*t->elem->size;
 
 	ret.len = nel;
 	ret.cap = cap;
-	ret.array = mal(size);
+
+	if(t->elem->kind&KindNoPointers)
+		ret.array = mallocgc(size, RefNoPointers, 1);
+	else
+		ret.array = mal(size);
 
 	FLUSH(&ret);
 
 	if(debug) {
-		prints("makeslice: nel=");
-		runtime·printint(nel);
-		prints("; cap=");
-		runtime·printint(cap);
-		prints("; width=");
-		runtime·printint(width);
-		prints("; ret=");
-		runtime·printslice(ret);
-		prints("\n");
+		printf("makeslice(%S, %d, %d); ret=", 
+			*t->string, nel, cap);
+ 		runtime·printslice(ret);
 	}
 }
 

src/pkg/runtime/type.go

@@ -31,10 +31,43 @@ type commonType struct {
 	alg		uint8;		// algorithm for copy+hash+cmp (../runtime/runtime.h:/AMEM)
 	align		uint8;		// alignment of variable with this type
 	fieldAlign	uint8;		// alignment of struct field with this type
+	kind		uint8;		// enumeration for C
 	string		*string;	// string form; unnecessary  but undeniably useful
 	*uncommonType;			// (relatively) uncommon fields
 }
 
+// Values for commonType.kind.
+const (
+	kindBool	= 1 + iota;
+	kindInt;
+	kindInt8;
+	kindInt16;
+	kindInt32;
+	kindInt64;
+	kindUint;
+	kindUint8;
+	kindUint16;
+	kindUint32;
+	kindUint64;
+	kindUintptr;
+	kindFloat;
+	kindFloat32;
+	kindFloat64;
+	kindArray;
+	kindChan;
+	kindDotDotDot;
+	kindFunc;
+	kindInterface;
+	kindMap;
+	kindPtr;
+	kindSlice;
+	kindString;
+	kindStruct;
+	kindUnsafePointer;
+
+	kindNoPointers	= 1 << 7;	// OR'ed into kind
+)
+
 // Method on non-interface type
 type method struct {
 	hash	uint32;		// hash of name + pkg + typ

src/pkg/runtime/type.h

@@ -13,6 +13,7 @@ typedef struct Method Method;
 typedef struct IMethod IMethod;
 typedef struct MapType MapType;
 typedef struct ChanType ChanType;
+typedef struct SliceType SliceType;
 
 struct CommonType
 {
@@ -21,10 +22,42 @@ struct CommonType
 	uint8 alg;
 	uint8 align;
 	uint8 fieldAlign;
+	uint8 kind;
 	String *string;
 	UncommonType *x;
 };
 
+enum {
+	KindBool = 1,
+	KindInt,
+	KindInt8,
+	KindInt16,
+	KindInt32,
+	KindInt64,
+	KindUint,
+	KindUint8,
+	KindUint16,
+	KindUint32,
+	KindUint64,
+	KindUintptr,
+	KindFloat,
+	KindFloat32,
+	KindFloat64,
+	KindArray,
+	KindChan,
+	KindDotDotDot,
+	KindFunc,
+	KindInterface,
+	KindMap,
+	KindPtr,
+	KindSlice,
+	KindString,
+	KindStruct,
+	KindUnsafePointer,
+	
+	KindNoPointers = 1<<7,
+};
+
 struct Method
 {
 	uint32 hash;
@@ -79,3 +112,10 @@ struct ChanType
 	Type *elem;
 	uintptr dir;
 };
+
+struct SliceType
+{
+	Type;
+	Type *elem;
+};
+