Fork the jemallocator crate, fix for nightly-2018-04-15

CC https://github.com/alexcrichton/jemallocator/pull/40,
https://github.com/rust-lang/rust/pull/49669

The new version of jemallocator requires a more recent jemalloc
https://github.com/alexcrichton/jemallocator/pull/34
which doesn’t build on our current Android toolchain
https://github.com/jemalloc/jemalloc/issues/1175.

To avoid blocking on figuring that out, duplicate ~70 lines
from jemallocator and use the older jemalloc-sys directly.

1 files changed, 77 insertions, 7 deletions

diff --git a/components/allocator/lib.rs b/components/allocator/lib.rs
index 6c248f08055..3d933599688 100644
--- a/components/allocator/lib.rs
+++ b/components/allocator/lib.rs
@@ -4,8 +4,7 @@
 
 //! Selecting the default global allocator for Servo
 
-#![cfg_attr(all(feature = "unstable", windows), feature(alloc_system, allocator_api))]
-#![cfg_attr(feature = "unstable", feature(global_allocator))]
+#![cfg_attr(feature = "unstable", feature(global_allocator, allocator_api, alloc_system))]
 
 #[cfg(feature = "unstable")]
 #[global_allocator]
@@ -16,19 +15,90 @@ pub use platform::*;
 
 #[cfg(all(feature = "unstable", not(windows)))]
 mod platform {
-    extern crate jemallocator;
+    extern crate jemalloc_sys as ffi;
 
-    pub use self::jemallocator::Jemalloc as Allocator;
-    use std::os::raw::c_void;
+    use std::alloc::{GlobalAlloc, Layout, Opaque, System};
+    use std::os::raw::{c_int, c_void};
 
     /// Get the size of a heap block.
     pub unsafe extern "C" fn usable_size(ptr: *const c_void) -> usize {
-        jemallocator::usable_size(ptr)
+        ffi::malloc_usable_size(ptr as *const _)
     }
 
     /// Memory allocation APIs compatible with libc
     pub mod libc_compat {
-        pub use super::jemallocator::ffi::{malloc, realloc, free};
+        pub use super::ffi::{malloc, realloc, free};
+    }
+
+    pub struct Allocator;
+
+    // The minimum alignment guaranteed by the architecture. This value is used to
+    // add fast paths for low alignment values.
+    #[cfg(all(any(target_arch = "arm",
+                  target_arch = "mips",
+                  target_arch = "mipsel",
+                  target_arch = "powerpc")))]
+    const MIN_ALIGN: usize = 8;
+    #[cfg(all(any(target_arch = "x86",
+                  target_arch = "x86_64",
+                  target_arch = "aarch64",
+                  target_arch = "powerpc64",
+                  target_arch = "powerpc64le",
+                  target_arch = "mips64",
+                  target_arch = "s390x",
+                  target_arch = "sparc64")))]
+    const MIN_ALIGN: usize = 16;
+
+    fn layout_to_flags(align: usize, size: usize) -> c_int {
+        // If our alignment is less than the minimum alignment they we may not
+        // have to pass special flags asking for a higher alignment. If the
+        // alignment is greater than the size, however, then this hits a sort of odd
+        // case where we still need to ask for a custom alignment. See #25 for more
+        // info.
+        if align <= MIN_ALIGN && align <= size {
+            0
+        } else {
+            // Equivalent to the MALLOCX_ALIGN(a) macro.
+            align.trailing_zeros() as _
+        }
+    }
+
+    unsafe impl GlobalAlloc for Allocator {
+        #[inline]
+        unsafe fn alloc(&self, layout: Layout) -> *mut Opaque {
+            let flags = layout_to_flags(layout.align(), layout.size());
+            ffi::mallocx(layout.size(), flags)  as *mut Opaque
+        }
+
+        #[inline]
+        unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut Opaque {
+            if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+                ffi::calloc(1, layout.size()) as *mut Opaque
+            } else {
+                let flags = layout_to_flags(layout.align(), layout.size()) | ffi::MALLOCX_ZERO;
+                ffi::mallocx(layout.size(), flags) as *mut Opaque
+            }
+        }
+
+        #[inline]
+        unsafe fn dealloc(&self, ptr: *mut Opaque, layout: Layout) {
+            let flags = layout_to_flags(layout.align(), layout.size());
+            ffi::sdallocx(ptr as *mut _, layout.size(), flags)
+        }
+
+        #[inline]
+        unsafe fn realloc(&self,
+                          ptr: *mut Opaque,
+                          layout: Layout,
+                          new_size: usize) -> *mut Opaque {
+            let flags = layout_to_flags(layout.align(), new_size);
+            ffi::rallocx(ptr as *mut _, new_size, flags) as *mut Opaque
+        }
+
+        #[inline]
+        fn oom(&self) -> ! {
+            System.oom()
+        }
     }
 }