diff options
Diffstat (limited to 'src/runtime/malloc.go')
| -rw-r--r-- | src/runtime/malloc.go | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go index f20ded5bf7..c57d8c617d 100644 --- a/src/runtime/malloc.go +++ b/src/runtime/malloc.go @@ -199,15 +199,21 @@ const ( // we further limit it to 31 bits. // // On ios/arm64, although 64-bit pointers are presumably - // available, pointers are truncated to 33 bits. Furthermore, - // only the top 4 GiB of the address space are actually available - // to the application, but we allow the whole 33 bits anyway for - // simplicity. - // TODO(mknyszek): Consider limiting it to 32 bits and using - // arenaBaseOffset to offset into the top 4 GiB. + // available, pointers are truncated to 33 bits in iOS <14. + // Furthermore, only the top 4 GiB of the address space are + // actually available to the application. In iOS >=14, more + // of the address space is available, and the OS can now + // provide addresses outside of those 33 bits. Pick 40 bits + // as a reasonable balance between address space usage by the + // page allocator, and flexibility for what mmap'd regions + // we'll accept for the heap. We can't just move to the full + // 48 bits because this uses too much address space for older + // iOS versions. + // TODO(mknyszek): Once iOS <14 is deprecated, promote ios/arm64 + // to a 48-bit address space like every other arm64 platform. // // WebAssembly currently has a limit of 4GB linear memory. - heapAddrBits = (_64bit*(1-sys.GoarchWasm)*(1-sys.GoosIos*sys.GoarchArm64))*48 + (1-_64bit+sys.GoarchWasm)*(32-(sys.GoarchMips+sys.GoarchMipsle)) + 33*sys.GoosIos*sys.GoarchArm64 + heapAddrBits = (_64bit*(1-sys.GoarchWasm)*(1-sys.GoosIos*sys.GoarchArm64))*48 + (1-_64bit+sys.GoarchWasm)*(32-(sys.GoarchMips+sys.GoarchMipsle)) + 40*sys.GoosIos*sys.GoarchArm64 // maxAlloc is the maximum size of an allocation. On 64-bit, // it's theoretically possible to allocate 1<<heapAddrBits bytes. On |