The old isARM() function was a portability trap. With the name it had, it seemed
like the obviously correct function to use, but it didn't include Thumb. In the
vast majority of cases where someone wants to ask "is the target Arm?", Thumb
*should* be included.
There are exactly 3 cases in the codebase where we do actually need to exclude
Thumb, although one of those is in Aro and mirrors a check in Clang that is
itself likely a bug. These rare cases can just add an extra isThumb() check.
* Use builtin.zig_backend instead of builtin.cpu.arch, the latter
does not yet compile under VK.
* Don't call regular _start for either opencl or vulkan. We might
even want to disable these completely.
The old `CallingConvention` type is replaced with the new
`NewCallingConvention`. References to `NewCallingConvention` in the
compiler are updated accordingly. In addition, a few parts of the
standard library are updated to use the new type correctly.
0ecc6332b4eb1ced547ffa38f57471134aaa4d13 improved things for thumb2, but thumb1
has a much smaller permissible instruction set. This commit makes that work.
The compiler actually doesn't need any functional changes for this: Sema
does reification based on the tag indices of `std.builtin.Type` already!
So, no zig1.wasm update is necessary.
This change is necessary to disallow name clashes between fields and
decls on a type, which is a prerequisite of #9938.
For csky, we can just always do the gb initialization. For riscv, the gp code is
temporarily pulled above the main switch until the blocking issue is resolved.
* Elaborate on the sub-variants of Variant I.
* Clarify the use of the TCB term.
* Rename a bunch of stuff to be more accurate/descriptive.
* Follow Zig's style around namespacing more.
* Use a structure for the ABI TCB.
No functional change intended.
Accesses to this global variable can require relocations on some platforms (e.g.
MIPS). If we do it before PIE relocations have been applied, we'll crash.
It's actually important for the ABI that r25 (t9) contains the address of the
called function, so that this standard prologue sequence works:
lui $2, %hi(_gp_disp)
addiu $2, $2, %lo(_gp_disp)
addu $gp, $2, $t9
(This is a bit similar to the ToC situation on powerpc that was fixed in
7bc78967b400322a0fc5651f37a1b0428c37fb9d.)
with this rewrite we can call functions inside of
inline assembly, enabling us to use the default start.zig logic
all that's left is to implement lr/sc loops for atomically manipulating
1 and 2 byte values, after which we can use the segfault handler logic.
Switches from using r1 as a temporary to r2. That way, we don't have to set the
`noat` assembler option. (r1 is the scratch register used by the assembler's
pseudoinstructions; the assembler warns when code uses that register explicitly
without `noat` set.)
