Proposed bug fix for issue rustwasm#85

nand-nor · Oct 16, 2019 · 43ed066 · 43ed066
1 parent e782897
commit 43ed066
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Showing 2 changed files with 21 additions and 6 deletions.
diff --git a/wee_alloc/src/imp_static_array.rs b/wee_alloc/src/imp_static_array.rs
@@ -6,17 +6,30 @@ use core::ptr::NonNull;
 use memory_units::{Bytes, Pages};
 use spin::Mutex;
 
+
 const SCRATCH_LEN_BYTES: usize = include!(concat!(env!("OUT_DIR"), "/wee_alloc_static_array_backend_size_bytes.txt"));
 static mut SCRATCH_HEAP: [u8; SCRATCH_LEN_BYTES] = [0; SCRATCH_LEN_BYTES];
 static mut OFFSET: Mutex<usize> = Mutex::new(0);
 
-pub(crate) unsafe fn alloc_pages(pages: Pages) -> Result<NonNull<u8>, AllocErr> {
+pub(crate) unsafe fn alloc_pages<B: Into<Bytes>>(pages: Pages, align: B) -> Result<NonNull<u8>, AllocErr> {
     let bytes: Bytes = pages.into();
     let mut offset = OFFSET.lock();
-    let end = bytes.0 + *offset;
-    if end < SCRATCH_LEN_BYTES {
-        let ptr = SCRATCH_HEAP[*offset..end].as_mut_ptr() as *mut u8;
-        *offset = end;
+    let mut end = bytes.0 + *offset;
+    let align = align.into();
+
+    if end < SCRATCH_LEN_BYTES  {
+        let mut ptr: *mut u8;
+        let mut count = 0;
+        ptr = SCRATCH_HEAP[*offset..end].as_mut_ptr() as *mut u8;
+        if ptr as usize & (align.0 - 1) != 0{
+            loop {
+                *offset += 1;
+                count += 1;
+                ptr = SCRATCH_HEAP[*offset..end + count].as_mut_ptr() as *mut u8;
+                if ptr as usize & (align.0 - 1) == 0 { break; }
+            }
+        }
+        *offset = end + count;
         NonNull::new(ptr).ok_or_else(|| AllocErr)
     } else {
         Err(AllocErr)
@@ -72,6 +85,8 @@ impl<T> Exclusive<T> {
     where
         for<'x> F: FnOnce(&'x mut T) -> U,
     {
+
+       // debug_println!("WIth exclusive access!");
         let mut guard = self.inner.lock();
         assert_not_in_use(self);
         set_in_use(self);

diff --git a/wee_alloc/src/lib.rs b/wee_alloc/src/lib.rs
@@ -780,7 +780,7 @@ impl<'a> AllocPolicy<'a> for LargeAllocPolicy {
         let size: Bytes = cmp::max(size.into(), (align + Self::MIN_CELL_SIZE) * Words(2));
 
         let pages: Pages = (size + size_of::<CellHeader>()).round_up_to();
-        let new_pages = imp::alloc_pages(pages)?;
+        let new_pages = imp::alloc_pages(pages, align)?;
         let allocated_size: Bytes = pages.into();
 
         let free_cell = &*FreeCell::from_uninitialized(