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va_args implementation for AAPCS. 

Implement the va args in codegen for AAPCS, this will be used as the
default va_args implementation for AArch64 rather than the va_args
llvm-ir as it currently is.

Copyright (c) 2020, Arm Limited.
This commit is contained in:
Jamie Cunliffe 2020-06-30 09:57:59 +01:00
parent a1528c432e
commit fc52b47e80
4 changed files with 151 additions and 3 deletions
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7
src/librustc_codegen_llvm/builder.rs
View File

@ -1279,7 +1279,12 @@ impl Builder<'a, 'll, 'tcx> {
self.call(lifetime_intrinsic, &[self.cx.const_u64(size), ptr], None);
}
fn phi(&mut self, ty: &'ll Type, vals: &[&'ll Value], bbs: &[&'ll BasicBlock]) -> &'ll Value {
pub(crate) fn phi(
&mut self,
ty: &'ll Type,
vals: &[&'ll Value],
bbs: &[&'ll BasicBlock],
) -> &'ll Value {
assert_eq!(vals.len(), bbs.len());
let phi = unsafe { llvm::LLVMBuildPhi(self.llbuilder, ty, UNNAMED) };
unsafe {

82
src/librustc_codegen_llvm/va_arg.rs
View File

@ -3,8 +3,9 @@ use crate::type_::Type;
use crate::type_of::LayoutLlvmExt;
use crate::value::Value;
use rustc_codegen_ssa::mir::operand::OperandRef;
use rustc_codegen_ssa::traits::{
BaseTypeMethods, BuilderMethods, ConstMethods, DerivedTypeMethods,
use rustc_codegen_ssa::{
common::IntPredicate,
traits::{BaseTypeMethods, BuilderMethods, ConstMethods, DerivedTypeMethods},
};
use rustc_middle::ty::layout::HasTyCtxt;
use rustc_middle::ty::Ty;
@ -89,6 +90,82 @@ fn emit_ptr_va_arg(
}
}
fn emit_aapcs_va_arg(
bx: &mut Builder<'a, 'll, 'tcx>,
list: OperandRef<'tcx, &'ll Value>,
target_ty: Ty<'tcx>,
) -> &'ll Value {
// Implementation of the AAPCS64 calling convention for va_args see
// https://github.com/ARM-software/abi-aa/blob/master/aapcs64/aapcs64.rst
let va_list_addr = list.immediate();
let layout = bx.cx.layout_of(target_ty);
let mut maybe_reg = bx.build_sibling_block("va_arg.maybe_reg");
let mut in_reg = bx.build_sibling_block("va_arg.in_reg");
let mut on_stack = bx.build_sibling_block("va_arg.on_stack");
let mut end = bx.build_sibling_block("va_arg.end");
let zero = bx.const_i32(0);
let offset_align = Align::from_bytes(4).unwrap();
assert!(&*bx.tcx().sess.target.target.target_endian == "little");
let gr_type = target_ty.is_any_ptr() || target_ty.is_integral();
let (reg_off, reg_top_index, slot_size) = if gr_type {
let gr_offs = bx.struct_gep(va_list_addr, 7);
let nreg = (layout.size.bytes() + 7) / 8;
(gr_offs, 3, nreg * 8)
} else {
let vr_off = bx.struct_gep(va_list_addr, 9);
let nreg = (layout.size.bytes() + 15) / 16;
(vr_off, 5, nreg * 16)
};
// if the offset >= 0 then the value will be on the stack
let mut reg_off_v = bx.load(reg_off, offset_align);
let use_stack = bx.icmp(IntPredicate::IntSGE, reg_off_v, zero);
bx.cond_br(use_stack, &on_stack.llbb(), &maybe_reg.llbb());
// The value at this point might be in a register, but there is a chance that
// it could be on the stack so we have to update the offset and then check
// the offset again.
if layout.align.abi.bytes() > 8 {
assert!(layout.align.abi.bytes() <= 16);
reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(15));
reg_off_v = maybe_reg.and(reg_off_v, bx.const_i32(-16));
}
let new_reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(slot_size as i32));
maybe_reg.store(new_reg_off_v, reg_off, offset_align);
// Check to see if we have overflowed the registers as a result of this.
// If we have then we need to use the stack for this value
let use_stack = maybe_reg.icmp(IntPredicate::IntSGT, new_reg_off_v, zero);
maybe_reg.cond_br(use_stack, &on_stack.llbb(), &in_reg.llbb());
let top = in_reg.struct_gep(va_list_addr, reg_top_index);
let top = in_reg.load(top, bx.tcx().data_layout.pointer_align.abi);
// reg_value = *(@top + reg_off_v);
let top = in_reg.gep(top, &[reg_off_v]);
let top = in_reg.bitcast(top, bx.cx.type_ptr_to(layout.llvm_type(bx)));
let reg_value = in_reg.load(top, layout.align.abi);
in_reg.br(&end.llbb());
// On Stack block
let stack_value =
emit_ptr_va_arg(&mut on_stack, list, target_ty, false, Align::from_bytes(8).unwrap(), true);
on_stack.br(&end.llbb());
let val = end.phi(
layout.immediate_llvm_type(bx),
&[reg_value, stack_value],
&[&in_reg.llbb(), &on_stack.llbb()],
);
*bx = end;
val
}
pub(super) fn emit_va_arg(
bx: &mut Builder<'a, 'll, 'tcx>,
addr: OperandRef<'tcx, &'ll Value>,
@ -115,6 +192,7 @@ pub(super) fn emit_va_arg(
("aarch64", _) if target.target_os == "ios" => {
emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(8).unwrap(), true)
}
("aarch64", _) => emit_aapcs_va_arg(bx, addr, target_ty),
// Windows x86_64
("x86_64", true) => {
let target_ty_size = bx.cx.size_of(target_ty).bytes();

55
src/test/run-make-fulldeps/c-link-to-rust-va-list-fn/checkrust.rs
View File

@ -91,3 +91,58 @@ pub unsafe extern "C" fn check_varargs_1(_: c_int, mut ap: ...) -> usize {
pub unsafe extern "C" fn check_varargs_2(_: c_int, _ap: ...) -> usize {
0
}
#[no_mangle]
pub unsafe extern "C" fn check_varargs_3(_: c_int, mut ap: ...) -> usize {
continue_if!(ap.arg::<c_int>() == 1);
continue_if!(ap.arg::<c_int>() == 2);
continue_if!(ap.arg::<c_int>() == 3);
continue_if!(ap.arg::<c_int>() == 4);
continue_if!(ap.arg::<c_int>() == 5);
continue_if!(ap.arg::<c_int>() == 6);
continue_if!(ap.arg::<c_int>() == 7);
continue_if!(ap.arg::<c_int>() == 8);
continue_if!(ap.arg::<c_int>() == 9);
continue_if!(ap.arg::<c_int>() == 10);
0
}
#[no_mangle]
pub unsafe extern "C" fn check_varargs_4(_: c_double, mut ap: ...) -> usize {
continue_if!(ap.arg::<c_double>() == 1.0);
continue_if!(ap.arg::<c_double>() == 2.0);
continue_if!(ap.arg::<c_double>() == 3.0);
continue_if!(ap.arg::<c_double>() == 4.0);
continue_if!(ap.arg::<c_double>() == 5.0);
continue_if!(ap.arg::<c_double>() == 6.0);
continue_if!(ap.arg::<c_double>() == 7.0);
continue_if!(ap.arg::<c_double>() == 8.0);
continue_if!(ap.arg::<c_double>() == 9.0);
continue_if!(ap.arg::<c_double>() == 10.0);
0
}
#[no_mangle]
pub unsafe extern "C" fn check_varargs_5(_: c_int, mut ap: ...) -> usize {
continue_if!(ap.arg::<c_double>() == 1.0);
continue_if!(ap.arg::<c_int>() == 1);
continue_if!(ap.arg::<c_double>() == 2.0);
continue_if!(ap.arg::<c_int>() == 2);
continue_if!(ap.arg::<c_double>() == 3.0);
continue_if!(ap.arg::<c_int>() == 3);
continue_if!(ap.arg::<c_double>() == 4.0);
continue_if!(ap.arg::<c_int>() == 4);
continue_if!(ap.arg::<c_int>() == 5);
continue_if!(ap.arg::<c_double>() == 5.0);
continue_if!(ap.arg::<c_int>() == 6);
continue_if!(ap.arg::<c_double>() == 6.0);
continue_if!(ap.arg::<c_int>() == 7);
continue_if!(ap.arg::<c_double>() == 7.0);
continue_if!(ap.arg::<c_int>() == 8);
continue_if!(ap.arg::<c_double>() == 8.0);
continue_if!(ap.arg::<c_int>() == 9);
continue_if!(ap.arg::<c_double>() == 9.0);
continue_if!(ap.arg::<c_int>() == 10);
continue_if!(ap.arg::<c_double>() == 10.0);
0
}

10
src/test/run-make-fulldeps/c-link-to-rust-va-list-fn/test.c
View File

@ -11,6 +11,9 @@ extern size_t check_list_copy_0(va_list ap);
extern size_t check_varargs_0(int fixed, ...);
extern size_t check_varargs_1(int fixed, ...);
extern size_t check_varargs_2(int fixed, ...);
extern size_t check_varargs_3(int fixed, ...);
extern size_t check_varargs_4(double fixed, ...);
extern size_t check_varargs_5(int fixed, ...);
int test_rust(size_t (*fn)(va_list), ...) {
size_t ret = 0;
@ -36,5 +39,12 @@ int main(int argc, char* argv[]) {
assert(check_varargs_2(0, "All", "of", "these", "are", "ignored", ".") == 0);
assert(check_varargs_3(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10) == 0);
assert(check_varargs_4(0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0) == 0);
assert(check_varargs_5(0, 1.0, 1, 2.0, 2, 3.0, 3, 4.0, 4, 5, 5.0, 6, 6.0, 7, 7.0, 8, 8.0,
9, 9.0, 10, 10.0) == 0);
return 0;
}