embryo of ir structs

ir.c

@@ -0,0 +1,70 @@
+#include <assert.h>
+
+#include "ir.h"
+
+const uint16_t vreg_base = 0x8000;
+
+static void ir_emit(ir_t *ir, vinsn_t *vi)
+{
+	ir->vi = realloc(ir->vi, ++ir->len);
+	assert(ir->vi);
+
+	ir->vi[ir->len - 1] = *vi;
+}
+
+void ir_emit_insn(ir_t *ir, struct bpf_insn bpf, uint16_t dst, uint16_t src)
+{
+	vinsn_t vi;
+
+	vi.vitype = VI_INSN;
+	vi.insn.bpf = bpf;
+	vi.insn.dst = dst;
+	vi.insn.src = src;
+	ir_emit(ir, &vi);
+}
+
+void ir_emit_label  (ir_t *ir, int16_t label)
+{
+	vinsn_t vi;
+
+	vi.vitype = VI_LABEL;
+	vi.label = label;
+}
+
+void ir_emit_reg_get(ir_t *ir, uint16_t reg)
+{
+	vinsn_t vi;
+
+	vi.vitype = VI_REG_GET;
+	vi.reg = reg;
+}
+
+void ir_emit_reg_put(ir_t *ir, uint16_t reg)
+{
+	vinsn_t vi;
+
+	vi.vitype = VI_REG_PUT;
+	vi.reg = reg;
+}
+
+int16_t ir_alloc_label (ir_t *ir)
+{
+	return ir->next_label--;
+}
+
+uint16_t ir_alloc_register(ir_t *ir)
+{
+	return ir->next_reg++;
+}
+
+ir_t *ir_new(void)
+{
+	ir_t *ir;
+
+	ir = calloc(1, sizeof(*ir));
+	assert(ir);
+
+	ir->next_reg = vreg_base;
+	ir->next_label = -1;
+	return ir;
+}

ir.h

@@ -0,0 +1,49 @@
+#ifndef _PLY_IR_H
+#define _PLY_IR_H
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <linux/bpf.h>
+
+typedef enum vitype {
+	VI_INSN,
+	VI_LABEL,
+	VI_REG_GET,
+	VI_REG_PUT,
+} vitype_t;
+
+typedef struct vinsn {
+	vitype_t vitype;
+
+	union {
+		struct {
+			struct bpf_insn bpf;
+			uint16_t dst;
+			uint16_t src;
+		} insn;
+
+		int16_t label;
+		uint16_t reg;
+	};
+} vinsn_t;
+
+typedef struct ir {
+	vinsn_t *vi;
+	size_t len;
+
+	int16_t next_label;
+	uint16_t next_reg;
+} ir_t;
+
+int16_t  ir_alloc_label   (ir_t *ir);
+uint16_t ir_alloc_register(ir_t *ir);
+
+void ir_emit_insn   (ir_t *ir, struct bpf_insn bpf, uint16_t dst, uint16_t src);
+void ir_emit_label  (ir_t *ir, int16_t label);
+void ir_emit_reg_get(ir_t *ir, uint16_t reg);
+void ir_emit_reg_put(ir_t *ir, uint16_t reg);
+
+ir_t *ir_new(void);
+
+#endif	/* _PLY_IR_H */