jit: Fix argument register clobbering

This patch fixes a long-standing bug on x86-64 where arguments in register are
clobbered. The problem is visible in ParameterPassingLivenessTest which passes
with this patch applied.

Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Tomek Grabiec <tgrabiec@gmail.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

3 files changed, 61 insertions, 11 deletions

diff --git a/include/jit/args.h b/include/jit/args.h
index fcaaab39..b527599a 100644
--- a/include/jit/args.h
+++ b/include/jit/args.h
@@ -8,7 +8,8 @@
 
 #include <assert.h>
 
-struct expression *convert_args(struct stack *mimic_stack, unsigned long nr_args, struct vm_method *method);
+struct expression **pop_args(struct stack *mimic_stack, unsigned long nr_args);
+struct expression *convert_args(struct expression **args_array, unsigned long nr_args, struct vm_method *method);
 struct expression *convert_native_args(struct stack *mimic_stack, unsigned long start_arg, unsigned long nr_args);
 
 #ifndef CONFIG_ARGS_MAP
diff --git a/jit/args.c b/jit/args.c
index b7e46aec..52a828d2 100644
--- a/jit/args.c
+++ b/jit/args.c
@@ -78,8 +78,36 @@ insert_arg(struct expression *root, struct expression *expr, struct vm_method *m
 	return args_list_expr(root, _expr);
 }
 
+struct expression **pop_args(struct stack *mimic_stack, unsigned long nr_args)
+{
+	struct expression **args_array;
+	unsigned long i;
+
+	args_array = malloc(nr_args * sizeof(void *));
+	if (!args_array)
+		return NULL;
+
+	/*
+	 * We scan the args map in reverse order, since the order of arguments
+	 * is already reversed.
+	 */
+	for (i = 0; i < nr_args; i++) {
+		struct expression *expr = stack_pop(mimic_stack);
+
+		args_array[i] = expr;
+
+		if (vm_type_is_pair(expr->vm_type))
+			i++;
+
+		if (i >= nr_args)
+			break;
+	}
+
+	return args_array;
+}
+
 struct expression *
-convert_args(struct stack *mimic_stack, unsigned long nr_args, struct vm_method *method)
+convert_args(struct expression **args_array, unsigned long nr_args, struct vm_method *method)
 {
 	struct expression *args_list = NULL;
 	unsigned long nr_total_args;
@@ -99,12 +127,8 @@ convert_args(struct stack *mimic_stack, unsigned long nr_args, struct vm_method
 		goto out;
 	}
 
-	/*
-	 * We scan the args map in reverse order, since the order of arguments
-	 * is already reversed.
-	 */
 	for (i = 0; i < nr_args; i++) {
-		struct expression *expr = stack_pop(mimic_stack);
+		struct expression *expr = args_array[i];
 
 		if (vm_type_is_pair(expr->vm_type))
 			i++;
@@ -132,6 +156,7 @@ convert_args(struct stack *mimic_stack, unsigned long nr_args, struct vm_method
 		 * use method index zero here for JNI methods.
 		 */
 	}
+
   out:
 	return args_list;
   error:
diff --git a/jit/invoke-bc.c b/jit/invoke-bc.c
index 17ae2c3c..d1709ad4 100644
--- a/jit/invoke-bc.c
+++ b/jit/invoke-bc.c
@@ -68,15 +68,39 @@ static int convert_and_add_args(struct parse_context *ctx,
 				struct vm_method *invoke_target,
 				struct statement *stmt)
 {
+	struct expression **args_array;
 	struct expression *args_list;
+	unsigned long nr_args, i;
 
-	args_list = convert_args(ctx->bb->mimic_stack,
-				 method_real_argument_count(invoke_target),
-				 invoke_target);
-	if (!args_list)
+	nr_args = method_real_argument_count(invoke_target);
+
+	args_array = pop_args(ctx->bb->mimic_stack, nr_args);
+	if (!args_array)
 		return warn("out of memory"), -EINVAL;
 
+	for (i = 0; i < nr_args; i++) {
+		struct expression *expr = args_array[i];
+
+		if (!expr_is_pure(expr))
+			args_array[i] = get_pure_expr(ctx, expr);
+
+		if (vm_type_is_pair(expr->vm_type))
+			i++;
+
+		if (i >= nr_args)
+			break;
+	}
+
+	args_list = convert_args(args_array, nr_args, invoke_target);
+	if (!args_list) {
+		free(args_array);
+		return warn("out of memory"), -EINVAL;
+	}
+
+	free(args_array);
+
 	stmt->args_list = &args_list->node;
+
 	return 0;
 }