Merge commit '9a0c32934ebe376128230aa8da3275697b2053e7' into sync_cg_clif-2021-03-05

1 files changed, 212 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_cranelift/example/alloc_system.rs b/compiler/rustc_codegen_cranelift/example/alloc_system.rs
new file mode 100644
index 00000000000..5f66ca67f2d
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+++ b/compiler/rustc_codegen_cranelift/example/alloc_system.rs
@@ -0,0 +1,212 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+#![no_std]
+#![feature(allocator_api, rustc_private)]
+#![cfg_attr(any(unix, target_os = "redox"), feature(libc))]
+
+// The minimum alignment guaranteed by the architecture. This value is used to
+// add fast paths for low alignment values.
+#[cfg(all(any(target_arch = "x86",
+              target_arch = "arm",
+              target_arch = "mips",
+              target_arch = "powerpc",
+              target_arch = "powerpc64")))]
+const MIN_ALIGN: usize = 8;
+#[cfg(all(any(target_arch = "x86_64",
+              target_arch = "aarch64",
+              target_arch = "mips64",
+              target_arch = "s390x",
+              target_arch = "sparc64")))]
+const MIN_ALIGN: usize = 16;
+
+pub struct System;
+#[cfg(any(windows, unix, target_os = "redox"))]
+mod realloc_fallback {
+    use core::alloc::{GlobalAlloc, Layout};
+    use core::cmp;
+    use core::ptr;
+    impl super::System {
+        pub(crate) unsafe fn realloc_fallback(&self, ptr: *mut u8, old_layout: Layout,
+                                              new_size: usize) -> *mut u8 {
+            // Docs for GlobalAlloc::realloc require this to be valid:
+            let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align());
+            let new_ptr = GlobalAlloc::alloc(self, new_layout);
+            if !new_ptr.is_null() {
+                let size = cmp::min(old_layout.size(), new_size);
+                ptr::copy_nonoverlapping(ptr, new_ptr, size);
+                GlobalAlloc::dealloc(self, ptr, old_layout);
+            }
+            new_ptr
+        }
+    }
+}
+#[cfg(any(unix, target_os = "redox"))]
+mod platform {
+    extern crate libc;
+    use core::ptr;
+    use MIN_ALIGN;
+    use System;
+    use core::alloc::{GlobalAlloc, Layout};
+    unsafe impl GlobalAlloc for System {
+        #[inline]
+        unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+            if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+                libc::malloc(layout.size()) as *mut u8
+            } else {
+                #[cfg(target_os = "macos")]
+                {
+                    if layout.align() > (1 << 31) {
+                        return ptr::null_mut()
+                    }
+                }
+                aligned_malloc(&layout)
+            }
+        }
+        #[inline]
+        unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+            if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+                libc::calloc(layout.size(), 1) as *mut u8
+            } else {
+                let ptr = self.alloc(layout.clone());
+                if !ptr.is_null() {
+                    ptr::write_bytes(ptr, 0, layout.size());
+                }
+                ptr
+            }
+        }
+        #[inline]
+        unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+            libc::free(ptr as *mut libc::c_void)
+        }
+        #[inline]
+        unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+            if layout.align() <= MIN_ALIGN && layout.align() <= new_size {
+                libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8
+            } else {
+                self.realloc_fallback(ptr, layout, new_size)
+            }
+        }
+    }
+    #[cfg(any(target_os = "android",
+              target_os = "hermit",
+              target_os = "redox",
+              target_os = "solaris"))]
+    #[inline]
+    unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
+        // On android we currently target API level 9 which unfortunately
+        // doesn't have the `posix_memalign` API used below. Instead we use
+        // `memalign`, but this unfortunately has the property on some systems
+        // where the memory returned cannot be deallocated by `free`!
+        //
+        // Upon closer inspection, however, this appears to work just fine with
+        // Android, so for this platform we should be fine to call `memalign`
+        // (which is present in API level 9). Some helpful references could
+        // possibly be chromium using memalign [1], attempts at documenting that
+        // memalign + free is ok [2] [3], or the current source of chromium
+        // which still uses memalign on android [4].
+        //
+        // [1]: https://codereview.chromium.org/10796020/
+        // [2]: https://code.google.com/p/android/issues/detail?id=35391
+        // [3]: https://bugs.chromium.org/p/chromium/issues/detail?id=138579
+        // [4]: https://chromium.googlesource.com/chromium/src/base/+/master/
+        //                                       /memory/aligned_memory.cc
+        libc::memalign(layout.align(), layout.size()) as *mut u8
+    }
+    #[cfg(not(any(target_os = "android",
+                  target_os = "hermit",
+                  target_os = "redox",
+                  target_os = "solaris")))]
+    #[inline]
+    unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
+        let mut out = ptr::null_mut();
+        let ret = libc::posix_memalign(&mut out, layout.align(), layout.size());
+        if ret != 0 {
+            ptr::null_mut()
+        } else {
+            out as *mut u8
+        }
+    }
+}
+#[cfg(windows)]
+#[allow(nonstandard_style)]
+mod platform {
+    use MIN_ALIGN;
+    use System;
+    use core::alloc::{GlobalAlloc, Layout};
+    type LPVOID = *mut u8;
+    type HANDLE = LPVOID;
+    type SIZE_T = usize;
+    type DWORD = u32;
+    type BOOL = i32;
+    extern "system" {
+        fn GetProcessHeap() -> HANDLE;
+        fn HeapAlloc(hHeap: HANDLE, dwFlags: DWORD, dwBytes: SIZE_T) -> LPVOID;
+        fn HeapReAlloc(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID, dwBytes: SIZE_T) -> LPVOID;
+        fn HeapFree(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID) -> BOOL;
+        fn GetLastError() -> DWORD;
+    }
+    #[repr(C)]
+    struct Header(*mut u8);
+    const HEAP_ZERO_MEMORY: DWORD = 0x00000008;
+    unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
+        &mut *(ptr as *mut Header).offset(-1)
+    }
+    unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
+        let aligned = ptr.add(align - (ptr as usize & (align - 1)));
+        *get_header(aligned) = Header(ptr);
+        aligned
+    }
+    #[inline]
+    unsafe fn allocate_with_flags(layout: Layout, flags: DWORD) -> *mut u8 {
+        let ptr = if layout.align() <= MIN_ALIGN {
+            HeapAlloc(GetProcessHeap(), flags, layout.size())
+        } else {
+            let size = layout.size() + layout.align();
+            let ptr = HeapAlloc(GetProcessHeap(), flags, size);
+            if ptr.is_null() {
+                ptr
+            } else {
+                align_ptr(ptr, layout.align())
+            }
+        };
+        ptr as *mut u8
+    }
+    unsafe impl GlobalAlloc for System {
+        #[inline]
+        unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+            allocate_with_flags(layout, 0)
+        }
+        #[inline]
+        unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+            allocate_with_flags(layout, HEAP_ZERO_MEMORY)
+        }
+        #[inline]
+        unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+            if layout.align() <= MIN_ALIGN {
+                let err = HeapFree(GetProcessHeap(), 0, ptr as LPVOID);
+                debug_assert!(err != 0, "Failed to free heap memory: {}",
+                              GetLastError());
+            } else {
+                let header = get_header(ptr);
+                let err = HeapFree(GetProcessHeap(), 0, header.0 as LPVOID);
+                debug_assert!(err != 0, "Failed to free heap memory: {}",
+                              GetLastError());
+            }
+        }
+        #[inline]
+        unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+            if layout.align() <= MIN_ALIGN {
+                HeapReAlloc(GetProcessHeap(), 0, ptr as LPVOID, new_size) as *mut u8
+            } else {
+                self.realloc_fallback(ptr, layout, new_size)
+            }
+        }
+    }
+}