src/librustc_target/abi/call/arm.rs

   1 use crate::abi::call::{Conv, FnAbi, ArgAbi, Reg, RegKind, Uniform};
   2 use crate::abi::{HasDataLayout, LayoutOf, TyLayout, TyLayoutMethods};
   3 use crate::spec::HasTargetSpec;
   4
   5 fn is_homogeneous_aggregate<'a, Ty, C>(cx: &C, arg: &mut ArgAbi<'a, Ty>)
   6                                      -> Option<Uniform>
   7     where Ty: TyLayoutMethods<'a, C> + Copy,
   8           C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>> + HasDataLayout
   9 {
  10     arg.layout.homogeneous_aggregate(cx).unit().and_then(|unit| {
  11         let size = arg.layout.size;
  12
  13         // Ensure we have at most four uniquely addressable members.
  14         if size > unit.size.checked_mul(4, cx).unwrap() {
  15             return None;
  16         }
  17
  18         let valid_unit = match unit.kind {
  19             RegKind::Integer => false,
  20             RegKind::Float => true,
  21             RegKind::Vector => size.bits() == 64 || size.bits() == 128
  22         };
  23
  24         valid_unit.then_some(Uniform { unit, total: size })
  25     })
  26 }
  27
  28 fn classify_ret<'a, Ty, C>(cx: &C, ret: &mut ArgAbi<'a, Ty>, vfp: bool)
  29     where Ty: TyLayoutMethods<'a, C> + Copy,
  30           C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>> + HasDataLayout
  31 {
  32     if !ret.layout.is_aggregate() {
  33         ret.extend_integer_width_to(32);
  34         return;
  35     }
  36
  37     if vfp {
  38         if let Some(uniform) = is_homogeneous_aggregate(cx, ret) {
  39             ret.cast_to(uniform);
  40             return;
  41         }
  42     }
  43
  44     let size = ret.layout.size;
  45     let bits = size.bits();
  46     if bits <= 32 {
  47         let unit = if bits <= 8 {
  48             Reg::i8()
  49         } else if bits <= 16 {
  50             Reg::i16()
  51         } else {
  52             Reg::i32()
  53         };
  54         ret.cast_to(Uniform {
  55             unit,
  56             total: size
  57         });
  58         return;
  59     }
  60     ret.make_indirect();
  61 }
  62
  63 fn classify_arg<'a, Ty, C>(cx: &C, arg: &mut ArgAbi<'a, Ty>, vfp: bool)
  64     where Ty: TyLayoutMethods<'a, C> + Copy,
  65           C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>> + HasDataLayout
  66 {
  67     if !arg.layout.is_aggregate() {
  68         arg.extend_integer_width_to(32);
  69         return;
  70     }
  71
  72     if vfp {
  73         if let Some(uniform) = is_homogeneous_aggregate(cx, arg) {
  74             arg.cast_to(uniform);
  75             return;
  76         }
  77     }
  78
  79     let align = arg.layout.align.abi.bytes();
  80     let total = arg.layout.size;
  81     arg.cast_to(Uniform {
  82         unit: if align <= 4 { Reg::i32() } else { Reg::i64() },
  83         total
  84     });
  85 }
  86
  87 pub fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
  88     where Ty: TyLayoutMethods<'a, C> + Copy,
  89           C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>> + HasDataLayout + HasTargetSpec
  90 {
  91     // If this is a target with a hard-float ABI, and the function is not explicitly
  92     // `extern "aapcs"`, then we must use the VFP registers for homogeneous aggregates.
  93     let vfp = cx.target_spec().llvm_target.ends_with("hf")
  94         && fn_abi.conv != Conv::ArmAapcs
  95         && !fn_abi.c_variadic;
  96
  97     if !fn_abi.ret.is_ignore() {
  98         classify_ret(cx, &mut fn_abi.ret, vfp);
  99     }
 100
 101     for arg in &mut fn_abi.args {
 102         if arg.is_ignore() { continue; }
 103         classify_arg(cx, arg, vfp);
 104     }
 105 }