bjit: fix problem with creating very large sets, tuples,..

the fixed blocksize of our region allocator was too small for very large actions
fix this by using the more powerful llvm::BumpPtrAllocator which handles allocation larger than the slab size

src/asm_writing/rewriter.cpp

@@ -2520,16 +2520,4 @@ PatchpointInitializationInfo initializePatchpoint3(void* slowpath_func, uint8_t*
 
     return PatchpointInitializationInfo(slowpath_start, slowpath_rtn_addr, continue_addr, std::move(live_outs));
 }
-
-void* Rewriter::RegionAllocator::alloc(size_t bytes) {
-    assert(bytes <= BLOCK_SIZE);
-    if (cur_offset + bytes > BLOCK_SIZE) {
-        blocks.emplace_back();
-        cur_offset = 0;
-    }
-
-    char* rtn = blocks.back() + cur_offset;
-    cur_offset += bytes;
-    return rtn;
-}
 }

src/asm_writing/rewriter.h

@@ -330,30 +330,9 @@ enum class ActionType { NORMAL, GUARD, MUTATION };
 #define LOCATION_PLACEHOLDER ((RewriterVar*)1)
 
 class Rewriter : public ICSlotRewrite::CommitHook {
-private:
-    class RegionAllocator {
-    public:
-        static const int BLOCK_SIZE = 1024; // reserve a bit of space for list/malloc overhead
-        std::list<char[BLOCK_SIZE]> blocks;
-
-        int cur_offset = BLOCK_SIZE + 1;
-
-        void* alloc(size_t bytes);
-    };
-    template <typename T> class RegionAllocatorAdaptor : public std::allocator<T> {
-    private:
-        RegionAllocator* allocator;
-
-    public:
-        T* allocate(size_t n) { return (T*)allocator->alloc(n); }
-        void deallocate(T* p, size_t n) {
-            // do nothing
-        }
-    };
-
 private:
     // This needs to be the first member:
-    RegionAllocator allocator;
+    llvm::BumpPtrAllocatorImpl<llvm::MallocAllocator, 512> allocator;
 
     // The rewriter has refcounting logic for handling owned RewriterVars.  If we own memory inside those RewriterVars,
     // we need to register that via registerOwnedAttr, which ends up here:
@@ -361,7 +340,7 @@ private:
 
 protected:
     // Allocates `bytes` bytes of data.  The allocation will get freed when the rewriter gets freed.
-    void* regionAlloc(size_t bytes) { return allocator.alloc(bytes); }
+    void* regionAlloc(size_t bytes) { return allocator.Allocate(bytes, 16 /* alignment */); }
 
     // Helps generating the best code for loading a const integer value.
     // By keeping track of the last known value of every register and reusing it.
@@ -425,7 +404,7 @@ protected:
     Rewriter(std::unique_ptr<ICSlotRewrite> rewrite, int num_args, const LiveOutSet& live_outs,
              bool needs_invalidation_support = true);
 
-    std::deque<RewriterAction, RegionAllocatorAdaptor<RewriterAction>> actions;
+    std::deque<RewriterAction> actions;
     template <typename F> RewriterAction* addAction(F&& action, llvm::ArrayRef<RewriterVar*> vars, ActionType type) {
         assertPhaseCollecting();
         for (RewriterVar* var : vars) {

test/tests/set_very_large.py

+# this used to crash the bjit
+for i in range(1000):
+ s = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99}