From febccd5f62a86319c0965ca0cdf773f1ea172900 Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@slava-pestovs-macbook-pro.local>
Date: Tue, 22 Dec 2009 15:49:21 +1300
Subject: [PATCH] vm: if an aging GC is triggered while uninitialized code
blocks are in the code heap, the code heap remembered set becomes out of
date, resulting in code blocks pointing at invalid data
---
vm/code_blocks.cpp | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/vm/code_blocks.cpp b/vm/code_blocks.cpp
index ae96def0a9..ec7a0e8998 100755
--- a/vm/code_blocks.cpp
+++ b/vm/code_blocks.cpp
@@ -293,10 +293,17 @@ struct initial_code_block_visitor {
void factor_vm::initialize_code_block(code_block *compiled)
{
std::map<code_block *,cell>::iterator iter = code->uninitialized_blocks.find(compiled);
+
initial_code_block_visitor visitor(this,iter->second);
compiled->each_instruction_operand(visitor);
compiled->flush_icache();
+
code->uninitialized_blocks.erase(iter);
+
+ /* next time we do a minor GC, we have to trace this code block, since
+ the newly-installed instruction operands might point to literals in
+ nursery or aging */
+ code->write_barrier(compiled);
}
/* Fixup labels. This is done at compile time, not image load time */
@@ -378,11 +385,16 @@ code_block *factor_vm::add_code_block(code_block_type type, cell code_, cell lab
if(to_boolean(labels.value()))
fixup_labels(labels.as<array>().untagged(),compiled);
- /* next time we do a minor GC, we have to scan the code heap for
- literals */
- this->code->write_barrier(compiled);
+ /* Once we are ready, fill in literal and word references in this code
+ block's instruction operands. In most cases this is done right after this
+ method returns, except when compiling words with the non-optimizing
+ compiler at the beginning of bootstrap */
this->code->uninitialized_blocks.insert(std::make_pair(compiled,literals.value()));
+ /* next time we do a minor GC, we have to trace this code block, since
+ the fields of the code_block struct might point into nursery or aging */
+ this->code->write_barrier(compiled);
+
return compiled;
}