Filter: Implement stack-based interpreter

[lttng-ust.git] / liblttng-ust / lttng-filter.h

diff --git a/liblttng-ust/lttng-filter.h b/liblttng-ust/lttng-filter.h
index 4ef1c757635eaf5edae394df19511c932b5682b0..5d22cca1c7e9d64a197667491ec5bf6d6611f317 100644 (file)
--- a/liblttng-ust/lttng-filter.h
+++ b/liblttng-ust/lttng-filter.h
@@ -28,6 +28,7 @@
 #include <helper.h>
 #include <lttng/ust-events.h>
 #include <stdint.h>
+#include <assert.h>
 #include <errno.h>
 #include <string.h>
 #include <inttypes.h>
@@ -35,7 +36,8 @@
 #include <usterr-signal-safe.h>
 #include "filter-bytecode.h"
 
-#define NR_REG         2
+/* Filter stack length, in number of entries */
+#define FILTER_STACK_LEN       8
 
 #ifndef min_t
 #define min_t(type, a, b)      \
@@ -67,30 +69,122 @@ struct bytecode_runtime {
        char data[0];
 };
 
-enum reg_type {
+enum entry_type {
        REG_S64,
        REG_DOUBLE,
        REG_STRING,
        REG_TYPE_UNKNOWN,
 };
 
-/* Validation registers */
-struct vreg {
-       enum reg_type type;
-       int literal;            /* is string literal ? */
+/* Validation stack */
+struct vstack_entry {
+       enum entry_type type;
 };
 
-/* Execution registers */
-struct reg {
-       enum reg_type type;
-       int64_t v;
-       double d;
+struct vstack {
+       int top;        /* top of stack */
+       struct vstack_entry e[FILTER_STACK_LEN];
+};
+
+static inline
+void vstack_init(struct vstack *stack)
+{
+       stack->top = -1;
+}
+
+static inline
+struct vstack_entry *vstack_ax(struct vstack *stack)
+{
+       if (unlikely(stack->top < 0))
+               return NULL;
+       return &stack->e[stack->top];
+}
+
+static inline
+struct vstack_entry *vstack_bx(struct vstack *stack)
+{
+       if (unlikely(stack->top < 1))
+               return NULL;
+       return &stack->e[stack->top - 1];
+}
+
+static inline
+int vstack_push(struct vstack *stack)
+{
+       if (stack->top >= FILTER_STACK_LEN - 1) {
+               ERR("Stack full\n");
+               return -EINVAL;
+       }
+       ++stack->top;
+       return 0;
+}
+
+static inline
+int vstack_pop(struct vstack *stack)
+{
+       if (unlikely(stack->top < 0)) {
+               ERR("Stack empty\n");
+               return -EINVAL;
+       }
+       stack->top--;
+       return 0;
+}
+
+/* Execution stack */
+struct estack_entry {
+       enum entry_type type;
+
+       union {
+               int64_t v;
+               double d;
+
+               struct {
+                       const char *str;
+               size_t seq_len;
+               int literal;            /* is string literal ? */
+               } s;
+       } u;
+};
 
-       const char *str;
-       size_t seq_len;
-       int literal;            /* is string literal ? */
+struct estack {
+       int top;        /* top of stack */
+       struct estack_entry e[FILTER_STACK_LEN];
 };
 
+static inline
+void estack_init(struct estack *stack)
+{
+       stack->top = -1;
+}
+
+static inline
+struct estack_entry *estack_ax(struct estack *stack)
+{
+       assert(stack->top >= 0);
+       return &stack->e[stack->top];
+}
+
+static inline
+struct estack_entry *estack_bx(struct estack *stack)
+{
+       assert(stack->top >= 1);
+       return &stack->e[stack->top - 1];
+}
+
+static inline
+void estack_push(struct estack *stack)
+{
+       assert(stack->top < FILTER_STACK_LEN - 1);
+       ++stack->top;
+}
+
+static inline
+void estack_pop(struct estack *stack)
+{
+       assert(stack->top >= 0);
+       stack->top--;
+}
+
 const char *print_op(enum filter_op op);
 
 int lttng_filter_validate_bytecode(struct bytecode_runtime *bytecode);