basic vreg->r0-9 replacement

ir.c

@@ -6,6 +6,7 @@
 #include <linux/bpf.h>
 
 #include "ir.h"
+#include "ply.h"
 #include "sym.h"
 #include "type.h"
 
@@ -225,11 +226,6 @@ void vinsn_dump(struct vinsn *vi, FILE *fp)
 		offset_dump(vi->label, fp);
 		fputc(':', fp);
 		return;
-	case VI_REG_GET:
-	case VI_REG_PUT:
-		fputs((vi->vitype == VI_REG_GET) ? "+ " : "- ", fp);
-		reg_dump(vi->reg, 0, fp);
-		return;
 	}
 }
 
@@ -245,9 +241,6 @@ void ir_dump(struct ir *ir, FILE *fp)
 		case VI_LDMAP:
 			fputc('\t', fp);
 			break;
-		case VI_REG_GET:
-		case VI_REG_PUT:
-			fputs("\e[2m", fp);
 		case VI_LABEL:
 		default:
 			break;
@@ -255,26 +248,6 @@ void ir_dump(struct ir *ir, FILE *fp)
 
 		vinsn_dump(vi, fp);
 
-		/* print multiple gets/puts on one line */
-		switch (vi->vitype) {
-		case VI_REG_GET:
-			for (; (vi + 1)->vitype == VI_REG_GET; vi++, i++) {
-				fputs(", ", fp);
-				reg_dump((vi + 1)->reg, 0, fp);
-			}
-			fputs("\e[0m", fp);
-			break;
-		case VI_REG_PUT:
-			for (; (vi + 1)->vitype == VI_REG_PUT; vi++, i++) {
-				fputs(", ", fp);
-				reg_dump((vi + 1)->reg, 0, fp);
-			}
-			fputs("\e[0m", fp);
-			break;
-		default:
-			break;
-		}
-
 		fputc('\n', fp);
 	}
 }
@@ -534,9 +507,82 @@ struct ir *ir_new(void)
 	return ir;
 }
 
+static void ir_bpf_vreg_replace(struct ir *ir, struct vinsn *last, int reg)
+{
+	struct vinsn *vi;
+
+	_d("ir_bpf_generate: v%d -> r%d\n", last->insn.src & ~vreg_base, reg);
+
+	for (vi = ir->vi; vi <= last; vi++) {
+		if (vi->vitype != VI_INSN)
+			continue;
+
+		if (vi->insn.dst == last->insn.src)
+			vi->insn.dst = reg;
+		if (vi->insn.src == last->insn.src)
+			vi->insn.src = reg;
+	}	
+}
 
 
-int ir_generate_bpf(struct ir *ir)
+int ir_bpf_registerize_one(struct ir *ir, struct vinsn *last)
 {
+	struct vinsn *vi;
+	uint16_t clean = 0x3ff;
+
+	for (vi = ir->vi; clean && (vi < last); vi++) {
+		if (vi->vitype != VI_INSN)
+			continue;
+
+		if (!(vi->insn.src & vreg_base))
+			clean &= ~(1 << vi->insn.src);
+		if (!(vi->insn.dst & vreg_base))
+			clean &= ~(1 << vi->insn.dst);
+		if (vi->insn.bpf.code == (BPF_JMP | BPF_CALL))
+			clean &= ~BPF_REG_CALLER_SAVE;
+	}
+
+	if (clean) {
+		int reg;
+
+		for (reg = BPF_REG_0; !(clean & 1); clean >>= 1, reg++);
+
+		ir_bpf_vreg_replace(ir, last, reg);
+		return 0;
+	}
+
+	/* TODO ir_bpf_vreg_spill(ir, last); */
+	return -1;
+}
+
+int ir_bpf_registerize(struct ir *ir)
+{
+	struct vinsn *vi;
+	int err = 0;
+
+	if (!ir->len)
+		return 0;
+	
+	for (vi = &ir->vi[ir->len - 1]; vi >= ir->vi; vi--) {
+		if (vi->vitype != VI_INSN)
+			continue;
+
+		if (vi->insn.src & vreg_base) {
+			err = ir_bpf_registerize_one(ir, vi);
+			if (err)
+				return err;
+		}
+	}
+	return err;
+}
+
+int ir_bpf_generate(struct ir *ir)
+{
+	int err;
+
+	err = ir_bpf_registerize(ir);
+	if (err)
+		return err;
+
 	return 0;
 }

ir.h

@@ -53,6 +53,9 @@
 
 #define BPF_REG_BP BPF_REG_10
 
+/* r0 is return value and r1-r5 are used for arguments */
+#define BPF_REG_CALLER_SAVE 0x3f
+
 static inline int bpf_width(size_t size)
 {
 	switch (size) {
@@ -72,8 +75,6 @@ enum vitype {
 	VI_INSN,
 	VI_LDMAP,
 	VI_LABEL,
-	VI_REG_GET,
-	VI_REG_PUT,
 };
 
 struct vinsn {
@@ -153,6 +154,6 @@ void ir_emit_bzero(struct ir *ir, ssize_t offset, size_t size);
 
 struct ir *ir_new(void);
 
-int ir_generate_bpf(struct ir *ir);
+int ir_bpf_generate(struct ir *ir);
 
 #endif	/* _PLY_IR_H */

ply.c

@@ -270,7 +270,7 @@ int run_bpf(struct pass *pass, struct ctx *ctx)
 	for (progp = ctx->progs; *progp; progp++) {
 		struct prog *prog = *progp;
 
-		err = ir_generate_bpf(prog->ir);
+		err = ir_bpf_generate(prog->ir);
 		if (err)
 			return err;
 	}
@@ -290,6 +290,7 @@ struct pass passes[] = {
 	{ .run = run_ir },
 	/* program flattened to vBPF instructions, now rewrite it to
 	 * fit into the actual hw/vm. */
+	{ .run = run_bpf },
 
 	/* BPF program ready */
 	{ NULL }