Implement IJMP instruction (indirect jump or computed goto)

TODO

@@ -2,7 +2,6 @@
 -  va_arg nodes
 -  BSTART, BEND nodes (to free data allocated by ALLOCA)
 -  ENTRY node for multy-entry units
--  IJMP
 -  guards
 -  variable name binding
 

ir.h

@@ -272,7 +272,7 @@ int ir_mem_flush(void *ptr, size_t size);
 	_(LOOP_BEGIN,   c2,   src, src, ___) /* loop start                  */ \
 	_(LOOP_END,     c1X1, src, beg, ___) /* loop end                    */ \
 	_(LOOP_EXIT,    c1X1, src, beg, ___) /* loop exit                   */ \
-	/* (IJMP)                                                           */ \
+	_(IJMP,         c2X1, src, def, ret) /* computed goto               */ \
 	\
 	/* guards (floating or not) ???                                     */ \
 	_(GUARD_TRUE,   c2,   src, def, ___) /* IF without second successor */ \
@@ -436,7 +436,8 @@ typedef struct _ir_strtab {
 	((op) == IR_MERGE || (op) == IR_LOOP_BEGIN)
 
 #define IR_IS_BB_END(op) \
-	((op) == IR_RETURN || (op) == IR_END || (op) == IR_LOOP_END || (op) == IR_IF || (op) == IR_SWITCH)
+	((op) == IR_RETURN || (op) == IR_END || (op) == IR_LOOP_END || (op) == IR_IF || \
+	 (op) == IR_SWITCH || (op) == IR_IJMP || (op) == IR_UNREACHABLE)
 
 #define IR_BB_UNREACHABLE      (1<<0)
 #define IR_BB_LOOP_HEADER      (1<<1)

ir_dump.c

@@ -68,7 +68,7 @@ void ir_dump_dot(ir_ctx *ctx, FILE *f)
 		if (flags & IR_OP_FLAG_CONTROL) {
 			if (insn->op == IR_START) {
 				fprintf(f, "\t{rank=min; n%d [label=\"%d: %s\",shape=box,style=\"rounded,filled\",fillcolor=red,rank=min];}\n", i, i, ir_op_name[insn->op]);
-			} else if (insn->op == IR_RETURN || insn->op == IR_UNREACHABLE) {
+			} else if (insn->op == IR_RETURN || insn->op == IR_UNREACHABLE || IR_IJMP) {
 				fprintf(f, "\t{rank=max; n%d [label=\"%d: %s\",shape=box,style=\"rounded,filled\",fillcolor=red,rank=max];}\n", i, i, ir_op_name[insn->op]);
 			} else if (flags & IR_OP_FLAG_MEM) {
 				fprintf(f, "\tn%d [label=\"%d: %s\",shape=box,style=filled,fillcolor=pink];\n", i, i, ir_op_name[insn->op]);

ir_emit_c.c

@@ -424,6 +424,13 @@ static void ir_emit_tailcall(ir_ctx *ctx, FILE *f, ir_insn *insn)
 	}
 }
 
+static void ir_emit_ijmp(ir_ctx *ctx, FILE *f, ir_insn *insn)
+{
+	fprintf(f, "\tgoto *(void**)(");
+	ir_emit_ref(ctx, f, insn->op2);
+	fprintf(f, ");\n");
+}
+
 static void ir_emit_alloca(ir_ctx *ctx, FILE *f, ir_ref def, ir_insn *insn)
 {
 	ir_emit_def_ref(ctx, f, def);
@@ -767,6 +774,9 @@ static int ir_emit_func(ir_ctx *ctx, FILE *f)
 				case IR_TAILCALL:
 					ir_emit_tailcall(ctx, f, insn);
 					break;
+				case IR_IJMP:
+					ir_emit_ijmp(ctx, f, insn);
+					break;
 				case IR_ALLOCA:
 					ir_emit_alloca(ctx, f, i, insn);
 					break;

ir_sccp.c

@@ -628,7 +628,7 @@ int ir_sccp(ir_ctx *ctx)
 					ir_sccp_replace_insn(ctx, _values, i, IR_UNUSED);
 				}
 			} else {
-				if (insn->op == IR_RETURN || insn->op == IR_UNREACHABLE) {
+				if (insn->op == IR_RETURN || insn->op == IR_UNREACHABLE || insn->op == IR_IJMP) {
 					ir_ref ref = ctx->ir_base[1].op1;
 					if (ref == i) {
 						ctx->ir_base[1].op1 = insn->op3;

ir_x86.dasc

@@ -4506,6 +4506,25 @@ static void ir_emit_tailcall(ir_ctx *ctx, ir_ref def, ir_insn *insn)
     }
 }
 
+static void ir_emit_ijmp(ir_ctx *ctx, ir_ref def, ir_insn *insn)
+{
+	ir_backend_data *data = ctx->data;
+	dasm_State **Dst = &data->dasm_state;
+	ir_reg op2_reg = ctx->regs[def][2];
+
+	if (op2_reg != IR_REG_NONE) {
+		if (op2_reg & IR_REG_SPILL_LOAD) {
+			op2_reg &= ~IR_REG_SPILL_LOAD;
+			ir_emit_load(ctx, IR_ADDR, op2_reg, insn->op2);
+		}
+		|	jmp Ra(op2_reg)
+	} else {
+		int32_t offset = ir_ref_spill_slot(ctx, insn->op2);
+		ir_reg fp = (ctx->flags & IR_USE_FRAME_POINTER) ? IR_REG_RBP : IR_REG_RSP;
+		|	jmp aword [Ra(fp)+offset]
+	}
+}
+
 static int ir_emit_dessa_move(ir_ctx *ctx, uint8_t type, ir_ref from, ir_ref to)
 {
 	ir_backend_data *data = ctx->data;
@@ -5796,6 +5815,9 @@ void *ir_emit(ir_ctx *ctx, size_t *size)
 				case IR_TAILCALL:
 					ir_emit_tailcall(ctx, i, insn);
 					break;
+				case IR_IJMP:
+					ir_emit_ijmp(ctx, i, insn);
+					break;
 				case IR_MEM_OP_INT:
 				case IR_MEM_INC:
 				case IR_MEM_DEC:

tests/c/ijmp_001.irt

@@ -0,0 +1,16 @@
+--TEST--
+001: IJMP - computed goto
+--ARGS--
+--emit-c
+--CODE--
+{
+	l_1 = START(l_2);
+	uintptr_t p = PARAM(l_1, "p", 1);
+	l_2 = IJMP(l_1, p);
+}
+--EXPECT--
+void test(uintptr_t p)
+{
+	uintptr_t d_1 = p;
+	goto *(void**)(d_1);
+}

tests/debug/ijmp_001.irt

@@ -0,0 +1,13 @@
+--TEST--
+001: IJMP - computed goto
+--ARGS--
+-S
+--CODE--
+{
+	l_1 = START(l_2);
+	uintptr_t p = PARAM(l_1, "p", 1);
+	l_2 = IJMP(l_1, p);
+}
+--EXPECT--
+test:
+	jmpq *%rdi