fix extern "aapcs" fn
#37814
fix extern "aapcs" fn
#37814
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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @alexcrichton (or someone else) soon. If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes. Please see the contribution instructions for more information. |
| @@ -274,10 +274,10 @@ impl FnType { | |||
| C => llvm::CCallConv, | |||
| Win64 => llvm::X86_64_Win64, | |||
| SysV64 => llvm::X86_64_SysV, | |||
| Aapcs => llvm::AapcsCallConv, | |||
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this doesn't match ffi.rs it's missing Arm
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It works: #[no_mangle]
pub extern "aapcs" fn foo(x: f64) -> f64 {
x
}
#[no_mangle]
pub extern "C" fn bar(x: f64) -> f64 {
x
}00000000 <foo>:
0: e24dd008 sub sp, sp, #8
4: ec410b10 vmov d0, r0, r1
8: ed8d0b00 vstr d0, [sp]
c: eaffffff b 10 <foo+0x10>
10: ed9d0b00 vldr d0, [sp]
14: ec510b10 vmov r0, r1, d0
18: e28dd008 add sp, sp, #8
1c: e12fff1e bx lr
Disassembly of section .text.bar:
00000000 <bar>:
0: e24dd008 sub sp, sp, #8
4: ed8d0b00 vstr d0, [sp]
8: eaffffff b c <bar+0xc>
c: ed9d0b00 vldr d0, [sp]
10: e28dd008 add sp, sp, #8
14: e12fff1e bx lr |
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(Compiled for |
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Maybe we should add a note about this ( I'm not sure about the exact policy here, however technically this is a breaking change so should probably tagged as such ( |
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Strictly speaking yeah it's a breaking change but in practice I imagine this will fix more code than it breaks (if it breaks anything...). @japaric want to edit the commit message and I'll r+? also cc @rust-lang/compiler, just to be aware |
to actually use the AAPCS calling convention closes rust-lang#37810 This is technically a [breaking-change] because it changes the ABI of `extern "aapcs"` functions that (a) involve `f32`/`f64` arguments/return values and (b) are compiled for arm-eabihf targets from "aapcs-vfp" (wrong) to "aapcs" (correct). Appendix: What these ABIs mean? - In the "aapcs-vfp" ABI or "hard float" calling convention: Floating point values are passed/returned through FPU registers (s0, s1, d0, etc.) - Whereas, in the "aapcs" ABI or "soft float" calling convention: Floating point values are passed/returned through general purpose registers (r0, r1, etc.) Mixing these ABIs can cause problems if the caller assumes that the routine is using one of these ABIs but it's actually using the other one.
Done. |
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@bors: r+ |
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📌 Commit 456ceba has been approved by |
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⌛ Testing commit 456ceba with merge fb025b4... |
fix `extern "aapcs" fn` to actually use the AAPCS calling convention closes #37810 This is technically a [breaking-change] because it changes the ABI of `extern "aapcs"` functions that (a) involve `f32`/`f64` arguments/return values and (b) are compiled for arm-eabihf targets from "aapcs-vfp" (wrong) to "aapcs" (correct). Appendix: What these ABIs mean? - In the "aapcs-vfp" ABI or "hard float" calling convention: Floating point values are passed/returned through FPU registers (s0, s1, d0, etc.) - Whereas, in the "aapcs" ABI or "soft float" calling convention: Floating point values are passed/returned through general purpose registers (r0, r1, etc.) Mixing these ABIs can cause problems if the caller assumes that the routine is using one of these ABIs but it's actually using the other one. --- r? @alexcrichton We are going this `extern "aapcs" fn` thing to implement some intrinsics (floatundidf) for the eabihf targets in order to comply with LLVM's calling convention of intrinsics. Oh, and the value of the enum came from [here](http://llvm.org/docs/doxygen/html/namespacellvm_1_1CallingConv.html). cc @TimNN @parched
to actually use the AAPCS calling convention
closes #37810
This is technically a [breaking-change] because it changes the ABI of
extern "aapcs"functions that (a) involvef32/f64arguments/returnvalues and (b) are compiled for arm-eabihf targets from
"aapcs-vfp" (wrong) to "aapcs" (correct).
Appendix:
What these ABIs mean?
In the "aapcs-vfp" ABI or "hard float" calling convention: Floating
point values are passed/returned through FPU registers (s0, s1, d0, etc.)
Whereas, in the "aapcs" ABI or "soft float" calling convention:
Floating point values are passed/returned through general purpose
registers (r0, r1, etc.)
Mixing these ABIs can cause problems if the caller assumes that the
routine is using one of these ABIs but it's actually using the other
one.
r? @alexcrichton We are going this
extern "aapcs" fnthing to implement some intrinsics (floatundidf) for the eabihf targets in order to comply with LLVM's calling convention of intrinsics.Oh, and the value of the enum came from here.
cc @TimNN @parched