I absolutely agree. Any significant information in the system must be defined in exactly one place. Preferably somewhere under our control. We should be exact on what it means, though. In this case it's used to select our data/heap model (which should be compatible to the compiler's data model, but not identical - we will use the same heap model for both GCC's LP64 and MSVC's LLP64 data models). As such, it is different from the V8_ARCH_* flags, which select the target back-end (we use the same heap model for IA32 and ARM architectures). Theoretically, we could have more than one heap model for the same architecture (e.g., full 64-bit or 64-bit with compressed pointers (or some other optimization we might make), or even, hopefully not, a 32-bit heap for the 64-bit backend).
With that reasoning, the LPC64/LLPC64 flags could just as well use a compiler defined flag (if one exists - and yes, that's a retraction of my former opinion :). The constant macros depend on the choice of compiler and choice of data model for the compiler, both something that we know, but that the compiler also knows. A single flag, e.g., V8_HEAP_64BIT, would be a better selector for the 64-bit pointer/heap model (vs. the current 32-bit model). /L On Mon, May 4, 2009 at 7:00 PM, <[email protected]> wrote: > This is a general comment about using V8_ARCH_X64 as the 64-bit marker > while porting and not only a particular comment about Bill's change. > > Please clean this up now and stick to the clean definition before it > gets a lot harder to deal with. Some ideas: Use the automatic defines > __WORDSIZE or __LP64__ or something that is defined in one place inside > globals.h or v8.h based on the compiler automatic defines: > #if defined(__LP64__) || (__LLP64__) > #define V8_64BIT 1 > #endif > > Thanks! > -Ivan > > > > > http://codereview.chromium.org/100336/diff/11/1006 > File src/globals.h (right): > > http://codereview.chromium.org/100336/diff/11/1006#newcode87 > Line 87: #ifdef V8_ARCH_X64 > There are potentially other 64-bit architectures outside x64. Please do > not "improve" the code for 64-bit cleanliness while making it harder to > port to other architectures. This will serve as a disservice in the long > time. Thanks! > > http://codereview.chromium.org/100336/diff/11/1006#newcode124 > Line 124: #ifdef V8_ARCH_X64 > ditto! > > > http://codereview.chromium.org/100336 > -- Lasse R.H. Nielsen [email protected] 'Faith without judgement merely degrades the spirit divine' --~--~---------~--~----~------------~-------~--~----~ v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev -~----------~----~----~----~------~----~------~--~---
