ref: 0d6543afdd79d7e9abbc09b266bb592d760ebf59
parent: ab2e4ae3a9cf10339b0340865bc12aa58a90fa4f
author: Roberto E. Vargas Caballero <[email protected]>
date: Wed Sep 13 12:19:29 EDT 2017
[lib] Add generic arena allocator At this moment we are using a specific arena allocator in cc2 for nodes, but there are other places in the code where an arena allocator can be used, so it is a good idea to have a generic implementation.
--- a/cc2/target/qbe/code.c
+++ b/cc2/target/qbe/code.c
@@ -13,7 +13,7 @@
static void binary(void), unary(void), store(void), jmp(void), ret(void),
branch(void), call(void), ecall(void), param(void),
- alloc(void), form2local(void), ldir(void), vastart(void),
+ asalloc(void), form2local(void), ldir(void), vastart(void),
vaarg(void);
static struct opdata {@@ -146,7 +146,7 @@
[ASCALLEX] = {.fun = ecall, .txt = ", ...)"}, [ASPAR] = {.fun = param, .txt = "%s %s, "}, [ASPARE] = {.fun = param, .txt = "%s %s"},- [ASALLOC] = {.fun = alloc},+ [ASALLOC] = {.fun = asalloc}, [ASFORM] = {.fun = form2local}, [ASVSTAR] = {.fun = vastart},@@ -516,7 +516,7 @@
}
static void
-alloc(void)
+asalloc(void)
{Symbol *sym = pc->to.u.sym;
Type *tp = &sym->type;
--- a/inc/scc.h
+++ b/inc/scc.h
@@ -19,6 +19,20 @@
unsigned n;
};
+typedef struct alloc Alloc;
+
+struct arena;
+union hdr;
+
+struct alloc {+ size_t size;
+ size_t nmemb;
+ size_t padding;
+ struct arena *arena;
+ union hdr *freep;
+};
+
+
extern void die(const char *fmt, ...);
extern void dbg(const char *fmt, ...);
extern void newitem(struct items *items, char *item);
@@ -26,3 +40,7 @@
extern void *xcalloc(size_t nmemb, size_t size);
extern char *xstrdup(const char *s);
extern void *xrealloc(void *buff, register size_t size);
+extern Alloc *alloc(size_t size, size_t nmemb);
+extern void dealloc(Alloc *allocp);
+extern void *new(Alloc *allocp);
+extern void delete(Alloc *allocp, void *p);
--- /dev/null
+++ b/lib/scc/alloc.c
@@ -1,0 +1,104 @@
+static char sccsid[] = "@(#) ./lib/alloc.c";
+#include <stdlib.h>
+#include "../../inc/scc.h"
+
+/*
+ * This is the most pedantic piece of code that I have written
+ * in my life. The next union is used to enforce the aligmnet
+ * of the address returned by new(). A union has the aligment
+ * of the field with the biggest aligment. This union has all
+ * the types that we use in scc, and we round all the address
+ * to the aligment of this struct, so we can be sure that any
+ * pointer using that address will be safe. The field ap is
+ * in the union to be sure that struct pointers are included
+ * in the list, although they will have the same aligment or
+ * smaller than void *, but I wanted to be pedantic.
+ */
+union hdr {+ union hdr *next;
+ struct arena *ap;
+ char c;
+ unsigned char uc;
+ int i;
+ short s;
+ long l;
+ long long ll;
+ float f;
+ double d;
+ long double ld;
+ void *vp;
+};
+
+struct arena {+ struct arena *next;
+ union hdr *array;
+};
+
+static void
+newarena(Alloc *allocp)
+{+ struct arena *ap;
+ union hdr *bp, *lim;
+ size_t unit, n = allocp->nmemb;
+
+ unit = (allocp->size-1) / sizeof(union hdr) + 1;
+ ap = xmalloc(sizeof(struct arena));
+ ap->array = xmalloc(unit * sizeof(union hdr) * n);
+
+ bp = ap->array;
+ for (lim = &bp[unit * (n-1)]; bp < lim; bp += unit)
+ bp->next = bp + unit;
+ bp->next = NULL;
+
+ ap->next = allocp->arena;
+ allocp->arena = ap;
+ allocp->freep = ap->array;
+}
+
+Alloc *
+alloc(size_t size, size_t nmemb)
+{+ Alloc *allocp = xmalloc(sizeof(*allocp));
+
+ allocp->size = size;
+ allocp->nmemb = nmemb;
+ allocp->arena = NULL;
+ allocp->freep = NULL;
+
+ return allocp;
+}
+
+void
+dealloc(Alloc *allocp)
+{+ struct arena *ap, *next;
+
+ for (ap = allocp->arena; ap; ap = next) {+ next = ap->next;
+ free(ap->array);
+ free(ap);
+ }
+ free(allocp);
+}
+
+void *
+new(Alloc *allocp)
+{+ union hdr *bp;
+
+ if (!allocp->freep)
+ newarena(allocp);
+ bp = allocp->freep;
+ allocp->freep = bp->next;
+
+ return bp;
+}
+
+void
+delete(Alloc *allocp, void *p)
+{+ union hdr *bp = p;
+
+ bp->next = allocp->freep;
+ allocp->freep = bp;
+}
--- a/lib/scc/libdep.mk
+++ b/lib/scc/libdep.mk
@@ -5,3 +5,4 @@
$(LIBDIR)/xmalloc.o \
$(LIBDIR)/xrealloc.o \
$(LIBDIR)/xstrdup.o \
+ $(LIBDIR)/alloc.o \