[PATCH] jit: clear mimic stack after conversion of *return instructions

[Tomek Grabiec]

Quoting JVM spec for ireturn:
"Any other values on the operand stack of the current method are discarded."

Signed-off-by: Tomek Grabiec <tgrab...@gmail.com>
---
 include/jit/basic-block.h |    1 +
 include/vm/stack.h        |    5 +++++
 jit/basic-block.c         |   10 ++++++++++
 jit/exception-bc.c        |    6 +-----
 jit/invoke-bc.c           |    2 ++
 5 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/include/jit/basic-block.h b/include/jit/basic-block.h
index 6aedff5..e50f6c6 100644
--- a/include/jit/basic-block.h
+++ b/include/jit/basic-block.h
@@ -89,6 +89,7 @@ unsigned char *bb_native_ptr(struct basic_block *bb);
 void resolution_block_init(struct resolution_block *block);
 bool branch_needs_resolution_block(struct basic_block *from, int idx);
 int bb_lookup_successor_index(struct basic_block *from, struct basic_block 
*to);
+void clear_mimic_stack(struct basic_block *bb);
 
 #define for_each_basic_block(bb, bb_list) list_for_each_entry(bb, bb_list, 
bb_list_node)
 #define for_each_basic_block_reverse(bb, bb_list) 
list_for_each_entry_reverse(bb, bb_list, bb_list_node)
diff --git a/include/vm/stack.h b/include/vm/stack.h
index 12120ee..4132863 100644
--- a/include/vm/stack.h
+++ b/include/vm/stack.h
@@ -33,4 +33,9 @@ static inline bool stack_is_empty(struct stack * stack)
        return !stack->nr_elements;
 }
 
+static inline void stack_clear(struct stack *stack)
+{
+       stack->nr_elements = 0;
+}
+
 #endif
diff --git a/jit/basic-block.c b/jit/basic-block.c
index 6a3075e..6de5c3f 100644
--- a/jit/basic-block.c
+++ b/jit/basic-block.c
@@ -254,3 +254,13 @@ bool branch_needs_resolution_block(struct basic_block 
*from, int idx)
 {
        return !list_is_empty(&from->resolution_blocks[idx].insns);
 }
+
+void clear_mimic_stack(struct basic_block *bb)
+{
+       struct expression *expr;
+
+       while (!stack_is_empty(bb->mimic_stack)) {
+               expr = stack_pop(bb->mimic_stack);
+               expr_put(expr);
+       }
+}
diff --git a/jit/exception-bc.c b/jit/exception-bc.c
index c0106cf..e1cd428 100644
--- a/jit/exception-bc.c
+++ b/jit/exception-bc.c
@@ -61,11 +61,7 @@ int convert_athrow(struct parse_context *ctx)
         * reference is not transferred to exception handlers in
         * BC2IR layer.
         */
-       while (!stack_is_empty(mimic_stack)) {
-               struct expression *expr = stack_pop(mimic_stack);
-
-               expr_put(expr);
-       }
+       clear_mimic_stack(ctx->bb);
 
        convert_statement(ctx, stmt);
 
diff --git a/jit/invoke-bc.c b/jit/invoke-bc.c
index 947f522..baed9cd 100644
--- a/jit/invoke-bc.c
+++ b/jit/invoke-bc.c
@@ -35,6 +35,7 @@ int convert_xreturn(struct parse_context *ctx)
        expr = stack_pop(ctx->bb->mimic_stack);
        return_stmt->return_value = &expr->node;
        convert_statement(ctx, return_stmt);
+       clear_mimic_stack(ctx->bb);
        return 0;
 }
 
@@ -47,6 +48,7 @@ int convert_return(struct parse_context *ctx)
        return_stmt->return_value = NULL;
 
        convert_statement(ctx, return_stmt);
+       clear_mimic_stack(ctx->bb);
        return 0;
 }
 
-- 
1.6.0.6


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