Auto merge of #68452 - msizanoen1:riscv-abi, r=nagisa,eddyb

Implement proper C ABI lowering for RISC-V

This is necessary for full RISC-V psABI compliance when passing argument across C FFI boundary.

cc @lenary

8 files changed, 1162 insertions, 16 deletions

diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs
index 0a5ab790adb..dbf421d26cb 100644
--- a/src/librustc/ty/layout.rs
+++ b/src/librustc/ty/layout.rs
@@ -2651,6 +2651,7 @@ where
                 .map(|(i, ty)| arg_of(ty, Some(i)))
                 .collect(),
             c_variadic: sig.c_variadic,
+            fixed_count: inputs.len(),
             conv,
         };
         fn_abi.adjust_for_abi(cx, sig.abi);
diff --git a/src/librustc_target/abi/call/mod.rs b/src/librustc_target/abi/call/mod.rs
index e3cbf176c35..8c7108229bd 100644
--- a/src/librustc_target/abi/call/mod.rs
+++ b/src/librustc_target/abi/call/mod.rs
@@ -120,6 +120,7 @@ impl Reg {
     reg_ctor!(i16, Integer, 16);
     reg_ctor!(i32, Integer, 32);
     reg_ctor!(i64, Integer, 64);
+    reg_ctor!(i128, Integer, 128);
 
     reg_ctor!(f32, Float, 32);
     reg_ctor!(f64, Float, 64);
@@ -538,6 +539,12 @@ pub struct FnAbi<'a, Ty> {
 
     pub c_variadic: bool,
 
+    /// The count of non-variadic arguments.
+    ///
+    /// Should only be different from args.len() when c_variadic is true.
+    /// This can be used to know wether an argument is variadic or not.
+    pub fixed_count: usize,
+
     pub conv: Conv,
 }
 
@@ -579,8 +586,7 @@ impl<'a, Ty> FnAbi<'a, Ty> {
             "nvptx" => nvptx::compute_abi_info(self),
             "nvptx64" => nvptx64::compute_abi_info(self),
             "hexagon" => hexagon::compute_abi_info(self),
-            "riscv32" => riscv::compute_abi_info(self, 32),
-            "riscv64" => riscv::compute_abi_info(self, 64),
+            "riscv32" | "riscv64" => riscv::compute_abi_info(cx, self),
             "wasm32" if cx.target_spec().target_os != "emscripten" => {
                 wasm32_bindgen_compat::compute_abi_info(self)
             }
diff --git a/src/librustc_target/abi/call/riscv.rs b/src/librustc_target/abi/call/riscv.rs
index 095e5aff744..11d6c4d8191 100644
--- a/src/librustc_target/abi/call/riscv.rs
+++ b/src/librustc_target/abi/call/riscv.rs
@@ -1,49 +1,358 @@
 // Reference: RISC-V ELF psABI specification
 // https://github.com/riscv/riscv-elf-psabi-doc
+//
+// Reference: Clang RISC-V ELF psABI lowering code
+// https://github.com/llvm/llvm-project/blob/8e780252a7284be45cf1ba224cabd884847e8e92/clang/lib/CodeGen/TargetInfo.cpp#L9311-L9773
 
-use crate::abi::call::{ArgAbi, FnAbi};
+use crate::abi::call::{ArgAbi, ArgAttribute, CastTarget, FnAbi, PassMode, Reg, RegKind, Uniform};
+use crate::abi::{
+    self, Abi, FieldPlacement, HasDataLayout, LayoutOf, Size, TyLayout, TyLayoutMethods,
+};
+use crate::spec::HasTargetSpec;
+
+#[derive(Copy, Clone)]
+enum RegPassKind {
+    Float(Reg),
+    Integer(Reg),
+    Unknown,
+}
+
+#[derive(Copy, Clone)]
+enum FloatConv {
+    FloatPair(Reg, Reg),
+    Float(Reg),
+    MixedPair(Reg, Reg),
+}
+
+#[derive(Copy, Clone)]
+struct CannotUseFpConv;
+
+fn is_riscv_aggregate<'a, Ty>(arg: &ArgAbi<'a, Ty>) -> bool {
+    match arg.layout.abi {
+        Abi::Vector { .. } => true,
+        _ => arg.layout.is_aggregate(),
+    }
+}
+
+fn should_use_fp_conv_helper<'a, Ty, C>(
+    cx: &C,
+    arg_layout: &TyLayout<'a, Ty>,
+    xlen: u64,
+    flen: u64,
+    field1_kind: &mut RegPassKind,
+    field2_kind: &mut RegPassKind,
+) -> Result<(), CannotUseFpConv>
+where
+    Ty: TyLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>>,
+{
+    match arg_layout.abi {
+        Abi::Scalar(ref scalar) => match scalar.value {
+            abi::Int(..) | abi::Pointer => {
+                if arg_layout.size.bits() > xlen {
+                    return Err(CannotUseFpConv);
+                }
+                match (*field1_kind, *field2_kind) {
+                    (RegPassKind::Unknown, _) => {
+                        *field1_kind = RegPassKind::Integer(Reg {
+                            kind: RegKind::Integer,
+                            size: arg_layout.size,
+                        });
+                    }
+                    (RegPassKind::Float(_), RegPassKind::Unknown) => {
+                        *field2_kind = RegPassKind::Integer(Reg {
+                            kind: RegKind::Integer,
+                            size: arg_layout.size,
+                        });
+                    }
+                    _ => return Err(CannotUseFpConv),
+                }
+            }
+            abi::F32 | abi::F64 => {
+                if arg_layout.size.bits() > flen {
+                    return Err(CannotUseFpConv);
+                }
+                match (*field1_kind, *field2_kind) {
+                    (RegPassKind::Unknown, _) => {
+                        *field1_kind =
+                            RegPassKind::Float(Reg { kind: RegKind::Float, size: arg_layout.size });
+                    }
+                    (_, RegPassKind::Unknown) => {
+                        *field2_kind =
+                            RegPassKind::Float(Reg { kind: RegKind::Float, size: arg_layout.size });
+                    }
+                    _ => return Err(CannotUseFpConv),
+                }
+            }
+        },
+        Abi::Vector { .. } | Abi::Uninhabited => return Err(CannotUseFpConv),
+        Abi::ScalarPair(..) | Abi::Aggregate { .. } => match arg_layout.fields {
+            FieldPlacement::Union(_) => {
+                if !arg_layout.is_zst() {
+                    return Err(CannotUseFpConv);
+                }
+            }
+            FieldPlacement::Array { count, .. } => {
+                for _ in 0..count {
+                    let elem_layout = arg_layout.field(cx, 0);
+                    should_use_fp_conv_helper(
+                        cx,
+                        &elem_layout,
+                        xlen,
+                        flen,
+                        field1_kind,
+                        field2_kind,
+                    )?;
+                }
+            }
+            FieldPlacement::Arbitrary { .. } => {
+                match arg_layout.variants {
+                    abi::Variants::Multiple { .. } => return Err(CannotUseFpConv),
+                    abi::Variants::Single { .. } => (),
+                }
+                for i in arg_layout.fields.index_by_increasing_offset() {
+                    let field = arg_layout.field(cx, i);
+                    should_use_fp_conv_helper(cx, &field, xlen, flen, field1_kind, field2_kind)?;
+                }
+            }
+        },
+    }
+    Ok(())
+}
+
+fn should_use_fp_conv<'a, Ty, C>(
+    cx: &C,
+    arg: &TyLayout<'a, Ty>,
+    xlen: u64,
+    flen: u64,
+) -> Option<FloatConv>
+where
+    Ty: TyLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>>,
+{
+    let mut field1_kind = RegPassKind::Unknown;
+    let mut field2_kind = RegPassKind::Unknown;
+    if should_use_fp_conv_helper(cx, arg, xlen, flen, &mut field1_kind, &mut field2_kind).is_err() {
+        return None;
+    }
+    match (field1_kind, field2_kind) {
+        (RegPassKind::Integer(l), RegPassKind::Float(r)) => Some(FloatConv::MixedPair(l, r)),
+        (RegPassKind::Float(l), RegPassKind::Integer(r)) => Some(FloatConv::MixedPair(l, r)),
+        (RegPassKind::Float(l), RegPassKind::Float(r)) => Some(FloatConv::FloatPair(l, r)),
+        (RegPassKind::Float(f), RegPassKind::Unknown) => Some(FloatConv::Float(f)),
+        _ => None,
+    }
+}
+
+fn classify_ret<'a, Ty, C>(cx: &C, arg: &mut ArgAbi<'a, Ty>, xlen: u64, flen: u64) -> bool
+where
+    Ty: TyLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>>,
+{
+    if let Some(conv) = should_use_fp_conv(cx, &arg.layout, xlen, flen) {
+        match conv {
+            FloatConv::Float(f) => {
+                arg.cast_to(f);
+            }
+            FloatConv::FloatPair(l, r) => {
+                arg.cast_to(CastTarget::pair(l, r));
+            }
+            FloatConv::MixedPair(l, r) => {
+                arg.cast_to(CastTarget::pair(l, r));
+            }
+        }
+        return false;
+    }
+
+    let total = arg.layout.size;
 
-fn classify_ret<Ty>(arg: &mut ArgAbi<'_, Ty>, xlen: u64) {
     // "Scalars wider than 2✕XLEN are passed by reference and are replaced in
     // the argument list with the address."
     // "Aggregates larger than 2✕XLEN bits are passed by reference and are
     // replaced in the argument list with the address, as are C++ aggregates
     // with nontrivial copy constructors, destructors, or vtables."
-    if arg.layout.size.bits() > 2 * xlen {
-        arg.make_indirect();
+    if total.bits() > 2 * xlen {
+        // We rely on the LLVM backend lowering code to lower passing a scalar larger than 2*XLEN.
+        if is_riscv_aggregate(arg) {
+            arg.make_indirect();
+        }
+        return true;
+    }
+
+    let xlen_reg = match xlen {
+        32 => Reg::i32(),
+        64 => Reg::i64(),
+        _ => unreachable!("Unsupported XLEN: {}", xlen),
+    };
+    if is_riscv_aggregate(arg) {
+        if total.bits() <= xlen {
+            arg.cast_to(xlen_reg);
+        } else {
+            arg.cast_to(Uniform { unit: xlen_reg, total: Size::from_bits(xlen * 2) });
+        }
+        return false;
     }
 
     // "When passed in registers, scalars narrower than XLEN bits are widened
     // according to the sign of their type up to 32 bits, then sign-extended to
     // XLEN bits."
-    arg.extend_integer_width_to(xlen); // this method only affects integer scalars
+    extend_integer_width(arg, xlen);
+    false
 }
 
-fn classify_arg<Ty>(arg: &mut ArgAbi<'_, Ty>, xlen: u64) {
+fn classify_arg<'a, Ty, C>(
+    cx: &C,
+    arg: &mut ArgAbi<'a, Ty>,
+    xlen: u64,
+    flen: u64,
+    is_vararg: bool,
+    avail_gprs: &mut u64,
+    avail_fprs: &mut u64,
+) where
+    Ty: TyLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>>,
+{
+    if !is_vararg {
+        match should_use_fp_conv(cx, &arg.layout, xlen, flen) {
+            Some(FloatConv::Float(f)) if *avail_fprs >= 1 => {
+                *avail_fprs -= 1;
+                arg.cast_to(f);
+                return;
+            }
+            Some(FloatConv::FloatPair(l, r)) if *avail_fprs >= 2 => {
+                *avail_fprs -= 2;
+                arg.cast_to(CastTarget::pair(l, r));
+                return;
+            }
+            Some(FloatConv::MixedPair(l, r)) if *avail_fprs >= 1 && *avail_gprs >= 1 => {
+                *avail_gprs -= 1;
+                *avail_fprs -= 1;
+                arg.cast_to(CastTarget::pair(l, r));
+                return;
+            }
+            _ => (),
+        }
+    }
+
+    let total = arg.layout.size;
+    let align = arg.layout.align.abi.bits();
+
     // "Scalars wider than 2✕XLEN are passed by reference and are replaced in
     // the argument list with the address."
     // "Aggregates larger than 2✕XLEN bits are passed by reference and are
     // replaced in the argument list with the address, as are C++ aggregates
     // with nontrivial copy constructors, destructors, or vtables."
-    if arg.layout.size.bits() > 2 * xlen {
-        arg.make_indirect();
+    if total.bits() > 2 * xlen {
+        // We rely on the LLVM backend lowering code to lower passing a scalar larger than 2*XLEN.
+        if is_riscv_aggregate(arg) {
+            arg.make_indirect();
+        }
+        if *avail_gprs >= 1 {
+            *avail_gprs -= 1;
+        }
+        return;
+    }
+
+    let double_xlen_reg = match xlen {
+        32 => Reg::i64(),
+        64 => Reg::i128(),
+        _ => unreachable!("Unsupported XLEN: {}", xlen),
+    };
+
+    let xlen_reg = match xlen {
+        32 => Reg::i32(),
+        64 => Reg::i64(),
+        _ => unreachable!("Unsupported XLEN: {}", xlen),
+    };
+
+    if total.bits() > xlen {
+        let align_regs = align > xlen;
+        if is_riscv_aggregate(arg) {
+            arg.cast_to(Uniform {
+                unit: if align_regs { double_xlen_reg } else { xlen_reg },
+                total: Size::from_bits(xlen * 2),
+            });
+        }
+        if align_regs && is_vararg {
+            *avail_gprs -= *avail_gprs % 2;
+        }
+        if *avail_gprs >= 2 {
+            *avail_gprs -= 2;
+        } else {
+            *avail_gprs = 0;
+        }
+        return;
+    } else if is_riscv_aggregate(arg) {
+        arg.cast_to(xlen_reg);
+        if *avail_gprs >= 1 {
+            *avail_gprs -= 1;
+        }
+        return;
     }
 
     // "When passed in registers, scalars narrower than XLEN bits are widened
     // according to the sign of their type up to 32 bits, then sign-extended to
     // XLEN bits."
-    arg.extend_integer_width_to(xlen); // this method only affects integer scalars
+    if *avail_gprs >= 1 {
+        extend_integer_width(arg, xlen);
+        *avail_gprs -= 1;
+    }
 }
 
-pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>, xlen: u64) {
+fn extend_integer_width<'a, Ty>(arg: &mut ArgAbi<'a, Ty>, xlen: u64) {
+    match arg.layout.abi {
+        Abi::Scalar(ref scalar) => {
+            match scalar.value {
+                abi::Int(i, _) => {
+                    // 32-bit integers are always sign-extended
+                    if i.size().bits() == 32 && xlen > 32 {
+                        if let PassMode::Direct(ref mut attrs) = arg.mode {
+                            attrs.set(ArgAttribute::SExt);
+                            return;
+                        }
+                    }
+                }
+                _ => (),
+            }
+        }
+        _ => (),
+    }
+    arg.extend_integer_width_to(xlen);
+}
+
+pub fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
+where
+    Ty: TyLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>> + HasDataLayout + HasTargetSpec,
+{
+    let flen = match &cx.target_spec().options.llvm_abiname[..] {
+        "ilp32f" | "lp64f" => 32,
+        "ilp32d" | "lp64d" => 64,
+        _ => 0,
+    };
+    let xlen = cx.data_layout().pointer_size.bits();
+
+    let mut avail_gprs = 8;
+    let mut avail_fprs = 8;
+
     if !fn_abi.ret.is_ignore() {
-        classify_ret(&mut fn_abi.ret, xlen);
+        if classify_ret(cx, &mut fn_abi.ret, xlen, flen) {
+            avail_gprs -= 1;
+        }
     }
 
-    for arg in &mut fn_abi.args {
+    for (i, arg) in fn_abi.args.iter_mut().enumerate() {
         if arg.is_ignore() {
             continue;
         }
-        classify_arg(arg, xlen);
+        classify_arg(
+            cx,
+            arg,
+            xlen,
+            flen,
+            i >= fn_abi.fixed_count,
+            &mut avail_gprs,
+            &mut avail_fprs,
+        );
     }
 }
diff --git a/src/test/auxiliary/rust_test_helpers.c b/src/test/auxiliary/rust_test_helpers.c
index c1fe8b7743a..897c940149b 100644
--- a/src/test/auxiliary/rust_test_helpers.c
+++ b/src/test/auxiliary/rust_test_helpers.c
@@ -168,6 +168,18 @@ struct floats {
     double c;
 };
 
+struct char_char_double {
+    uint8_t a;
+    uint8_t b;
+    double c;
+};
+
+struct char_char_float {
+    uint8_t a;
+    uint8_t b;
+    float c;
+};
+
 struct quad
 rust_dbg_abi_1(struct quad q) {
     struct quad qq = { q.c + 1,
@@ -185,6 +197,23 @@ rust_dbg_abi_2(struct floats f) {
     return ff;
 }
 
+struct char_char_double
+rust_dbg_abi_3(struct char_char_double a) {
+    struct char_char_double ccd = { a.a + 1,
+                                    a.b - 1,
+                                    a.c + 1.0 };
+    return ccd;
+}
+
+struct char_char_float
+rust_dbg_abi_4(struct char_char_float a) {
+    struct char_char_float ccd = { a.a + 1,
+                                   a.b - 1,
+                                   a.c + 1.0 };
+    return ccd;
+}
+
+
 int
 rust_dbg_static_mut = 3;
 
diff --git a/src/test/codegen/riscv-abi/riscv64-lp64-lp64f-lp64d-abi.rs b/src/test/codegen/riscv-abi/riscv64-lp64-lp64f-lp64d-abi.rs
new file mode 100644
index 00000000000..f0f052fe5c5
--- /dev/null
+++ b/src/test/codegen/riscv-abi/riscv64-lp64-lp64f-lp64d-abi.rs
@@ -0,0 +1,181 @@
+// ignore-tidy-linelength
+// compile-flags: -C no-prepopulate-passes
+// only-riscv64
+// only-linux
+#![crate_type = "lib"]
+#![allow(improper_ctypes)]
+
+// CHECK: define void @f_void()
+#[no_mangle]
+pub extern "C" fn f_void() {}
+
+// CHECK: define zeroext i1 @f_scalar_0(i1 zeroext %a)
+#[no_mangle]
+pub extern "C" fn f_scalar_0(a: bool) -> bool {
+    a
+}
+
+// CHECK: define signext i8 @f_scalar_1(i8 signext %x)
+#[no_mangle]
+pub extern "C" fn f_scalar_1(x: i8) -> i8 {
+    x
+}
+
+// CHECK: define zeroext i8 @f_scalar_2(i8 zeroext %x)
+#[no_mangle]
+pub extern "C" fn f_scalar_2(x: u8) -> u8 {
+    x
+}
+
+// CHECK: define signext i32 @f_scalar_3(i32 signext %x)
+#[no_mangle]
+pub extern "C" fn f_scalar_3(x: i32) -> u32 {
+    x as u32
+}
+
+// CHECK: define i64 @f_scalar_4(i64 %x)
+#[no_mangle]
+pub extern "C" fn f_scalar_4(x: i64) -> i64 {
+    x
+}
+
+// CHECK: define float @f_fp_scalar_1(float)
+#[no_mangle]
+pub extern "C" fn f_fp_scalar_1(x: f32) -> f32 {
+    x
+}
+// CHECK: define double @f_fp_scalar_2(double)
+#[no_mangle]
+pub extern "C" fn f_fp_scalar_2(x: f64) -> f64 {
+    x
+}
+
+#[repr(C)]
+pub struct Empty {}
+
+// CHECK: define void @f_agg_empty_struct()
+#[no_mangle]
+pub extern "C" fn f_agg_empty_struct(e: Empty) -> Empty {
+    e
+}
+
+#[repr(C)]
+pub struct Tiny {
+    a: u16,
+    b: u16,
+    c: u16,
+    d: u16,
+}
+
+// CHECK: define void @f_agg_tiny(i64)
+#[no_mangle]
+pub extern "C" fn f_agg_tiny(mut e: Tiny) {
+    e.a += e.b;
+    e.c += e.d;
+}
+
+// CHECK: define i64 @f_agg_tiny_ret()
+#[no_mangle]
+pub extern "C" fn f_agg_tiny_ret() -> Tiny {
+    Tiny { a: 1, b: 2, c: 3, d: 4 }
+}
+
+#[repr(C)]
+pub struct Small {
+    a: i64,
+    b: *mut i64,
+}
+
+// CHECK: define void @f_agg_small([2 x i64])
+#[no_mangle]
+pub extern "C" fn f_agg_small(mut x: Small) {
+    x.a += unsafe { *x.b };
+    x.b = &mut x.a;
+}
+
+// CHECK: define [2 x i64] @f_agg_small_ret()
+#[no_mangle]
+pub extern "C" fn f_agg_small_ret() -> Small {
+    Small { a: 1, b: core::ptr::null_mut() }
+}
+
+#[repr(C)]
+pub struct SmallAligned {
+    a: i128,
+}
+
+// CHECK: define void @f_agg_small_aligned(i128)
+#[no_mangle]
+pub extern "C" fn f_agg_small_aligned(mut x: SmallAligned) {
+    x.a += x.a;
+}
+
+#[repr(C)]
+pub struct Large {
+    a: i64,
+    b: i64,
+    c: i64,
+    d: i64,
+}
+
+// CHECK: define void @f_agg_large(%Large* {{.*}}%x)
+#[no_mangle]
+pub extern "C" fn f_agg_large(mut x: Large) {
+    x.a = x.b + x.c + x.d;
+}
+
+// CHECK: define void @f_agg_large_ret(%Large* {{.*}}sret{{.*}}, i32 signext %i, i8 signext %j)
+#[no_mangle]
+pub extern "C" fn f_agg_large_ret(i: i32, j: i8) -> Large {
+    Large { a: 1, b: 2, c: 3, d: 4 }
+}
+
+// CHECK: define void @f_scalar_stack_1(i64, [2 x i64], i128, %Large* {{.*}}%d, i8 zeroext %e, i8 signext %f, i8 %g, i8 %h)
+#[no_mangle]
+pub extern "C" fn f_scalar_stack_1(
+    a: Tiny,
+    b: Small,
+    c: SmallAligned,
+    d: Large,
+    e: u8,
+    f: i8,
+    g: u8,
+    h: i8,
+) {
+}
+
+// CHECK: define void @f_scalar_stack_2(%Large* {{.*}}sret{{.*}}, i64 %a, i128, i128, i64 %d, i8 zeroext %e, i8 %f, i8 %g)
+#[no_mangle]
+pub extern "C" fn f_scalar_stack_2(
+    a: u64,
+    b: SmallAligned,
+    c: SmallAligned,
+    d: u64,
+    e: u8,
+    f: i8,
+    g: u8,
+) -> Large {
+    Large { a: a as i64, b: e as i64, c: f as i64, d: g as i64 }
+}
+
+extern "C" {
+    fn f_va_callee(_: i32, ...) -> i32;
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn f_va_caller() {
+    // CHECK: call signext i32 (i32, ...) @f_va_callee(i32 signext 1, i32 signext 2, i64 3, double {{.*}}, double {{.*}}, i64 {{.*}}, [2 x i64] {{.*}}, i128 {{.*}}, %Large* {{.*}})
+    f_va_callee(
+        1,
+        2i32,
+        3i64,
+        4.0f64,
+        5.0f64,
+        Tiny { a: 1, b: 2, c: 3, d: 4 },
+        Small { a: 10, b: core::ptr::null_mut() },
+        SmallAligned { a: 11 },
+        Large { a: 12, b: 13, c: 14, d: 15 },
+    );
+    // CHECK: call signext i32 (i32, ...) @f_va_callee(i32 signext 1, i32 signext 2, i32 signext 3, i32 signext 4, i128 {{.*}}, i32 signext 6, i32 signext 7, i32 8, i32 9)
+    f_va_callee(1, 2i32, 3i32, 4i32, SmallAligned { a: 5 }, 6i32, 7i32, 8i32, 9i32);
+}
diff --git a/src/test/codegen/riscv-abi/riscv64-lp64d-abi.rs b/src/test/codegen/riscv-abi/riscv64-lp64d-abi.rs
new file mode 100644
index 00000000000..66a3b9e4952
--- /dev/null
+++ b/src/test/codegen/riscv-abi/riscv64-lp64d-abi.rs
@@ -0,0 +1,293 @@
+// ignore-tidy-linelength
+// compile-flags: -C no-prepopulate-passes
+// only-riscv64
+// only-linux
+#![crate_type = "lib"]
+
+// CHECK: define void @f_fpr_tracking(double, double, double, double, double, double, double, double, i8 zeroext %i)
+#[no_mangle]
+pub extern "C" fn f_fpr_tracking(
+    a: f64,
+    b: f64,
+    c: f64,
+    d: f64,
+    e: f64,
+    f: f64,
+    g: f64,
+    h: f64,
+    i: u8,
+) {
+}
+
+#[repr(C)]
+pub struct Double {
+    f: f64,
+}
+
+#[repr(C)]
+pub struct DoubleDouble {
+    f: f64,
+    g: f64,
+}
+
+#[repr(C)]
+pub struct DoubleFloat {
+    f: f64,
+    g: f32,
+}
+
+// CHECK: define void @f_double_s_arg(double)
+#[no_mangle]
+pub extern "C" fn f_double_s_arg(a: Double) {}
+
+// CHECK: define double @f_ret_double_s()
+#[no_mangle]
+pub extern "C" fn f_ret_double_s() -> Double {
+    Double { f: 1. }
+}
+
+// CHECK: define void @f_double_double_s_arg({ double, double })
+#[no_mangle]
+pub extern "C" fn f_double_double_s_arg(a: DoubleDouble) {}
+
+// CHECK: define { double, double } @f_ret_double_double_s()
+#[no_mangle]
+pub extern "C" fn f_ret_double_double_s() -> DoubleDouble {
+    DoubleDouble { f: 1., g: 2. }
+}
+
+// CHECK: define void @f_double_float_s_arg({ double, float })
+#[no_mangle]
+pub extern "C" fn f_double_float_s_arg(a: DoubleFloat) {}
+
+// CHECK: define { double, float } @f_ret_double_float_s()
+#[no_mangle]
+pub extern "C" fn f_ret_double_float_s() -> DoubleFloat {
+    DoubleFloat { f: 1., g: 2. }
+}
+
+// CHECK: define void @f_double_double_s_arg_insufficient_fprs(double, double, double, double, double, double, double, [2 x i64])
+#[no_mangle]
+pub extern "C" fn f_double_double_s_arg_insufficient_fprs(
+    a: f64,
+    b: f64,
+    c: f64,
+    d: f64,
+    e: f64,
+    f: f64,
+    g: f64,
+    h: DoubleDouble,
+) {
+}
+
+#[repr(C)]
+pub struct DoubleInt8 {
+    f: f64,
+    i: i8,
+}
+
+#[repr(C)]
+pub struct DoubleUInt8 {
+    f: f64,
+    i: u8,
+}
+
+#[repr(C)]
+pub struct DoubleInt32 {
+    f: f64,
+    i: i32,
+}
+
+#[repr(C)]
+pub struct DoubleInt64 {
+    f: f64,
+    i: i64,
+}
+
+// CHECK: define void @f_double_int8_s_arg({ double, i8 })
+#[no_mangle]
+pub extern "C" fn f_double_int8_s_arg(a: DoubleInt8) {}
+
+// CHECK: define { double, i8 } @f_ret_double_int8_s()
+#[no_mangle]
+pub extern "C" fn f_ret_double_int8_s() -> DoubleInt8 {
+    DoubleInt8 { f: 1., i: 2 }
+}
+
+// CHECK: define void @f_double_int32_s_arg({ double, i32 })
+#[no_mangle]
+pub extern "C" fn f_double_int32_s_arg(a: DoubleInt32) {}
+
+// CHECK: define { double, i32 } @f_ret_double_int32_s()
+#[no_mangle]
+pub extern "C" fn f_ret_double_int32_s() -> DoubleInt32 {
+    DoubleInt32 { f: 1., i: 2 }
+}
+
+// CHECK: define void @f_double_uint8_s_arg({ double, i8 })
+#[no_mangle]
+pub extern "C" fn f_double_uint8_s_arg(a: DoubleUInt8) {}
+
+// CHECK: define { double, i8 } @f_ret_double_uint8_s()
+#[no_mangle]
+pub extern "C" fn f_ret_double_uint8_s() -> DoubleUInt8 {
+    DoubleUInt8 { f: 1., i: 2 }
+}
+
+// CHECK: define void @f_double_int64_s_arg({ double, i64 })
+#[no_mangle]
+pub extern "C" fn f_double_int64_s_arg(a: DoubleInt64) {}
+
+// CHECK: define { double, i64 } @f_ret_double_int64_s()
+#[no_mangle]
+pub extern "C" fn f_ret_double_int64_s() -> DoubleInt64 {
+    DoubleInt64 { f: 1., i: 2 }
+}
+
+// CHECK: define void @f_double_int8_s_arg_insufficient_gprs(i32 signext %a, i32 signext %b, i32 signext %c, i32 signext %d, i32 signext %e, i32 signext %f, i32 signext %g, i32 signext %h, [2 x i64])
+#[no_mangle]
+pub extern "C" fn f_double_int8_s_arg_insufficient_gprs(
+    a: i32,
+    b: i32,
+    c: i32,
+    d: i32,
+    e: i32,
+    f: i32,
+    g: i32,
+    h: i32,
+    i: DoubleInt8,
+) {
+}
+
+// CHECK: define void @f_struct_double_int8_insufficient_fprs(float, double, double, double, double, double, double, double, [2 x i64])
+#[no_mangle]
+pub extern "C" fn f_struct_double_int8_insufficient_fprs(
+    a: f32,
+    b: f64,
+    c: f64,
+    d: f64,
+    e: f64,
+    f: f64,
+    g: f64,
+    h: f64,
+    i: DoubleInt8,
+) {
+}
+
+#[repr(C)]
+pub struct DoubleArr1 {
+    a: [f64; 1],
+}
+
+// CHECK: define void @f_doublearr1_s_arg(double)
+#[no_mangle]
+pub extern "C" fn f_doublearr1_s_arg(a: DoubleArr1) {}
+
+// CHECK: define double @f_ret_doublearr1_s()
+#[no_mangle]
+pub extern "C" fn f_ret_doublearr1_s() -> DoubleArr1 {
+    DoubleArr1 { a: [1.] }
+}
+
+#[repr(C)]
+pub struct DoubleArr2 {
+    a: [f64; 2],
+}
+
+// CHECK: define void @f_doublearr2_s_arg({ double, double })
+#[no_mangle]
+pub extern "C" fn f_doublearr2_s_arg(a: DoubleArr2) {}
+
+// CHECK: define { double, double } @f_ret_doublearr2_s()
+#[no_mangle]
+pub extern "C" fn f_ret_doublearr2_s() -> DoubleArr2 {
+    DoubleArr2 { a: [1., 2.] }
+}
+
+#[repr(C)]
+pub struct Tricky1 {
+    f: [f64; 1],
+}
+
+#[repr(C)]
+pub struct DoubleArr2Tricky1 {
+    g: [Tricky1; 2],
+}
+
+// CHECK: define void @f_doublearr2_tricky1_s_arg({ double, double })
+#[no_mangle]
+pub extern "C" fn f_doublearr2_tricky1_s_arg(a: DoubleArr2Tricky1) {}
+
+// CHECK: define { double, double } @f_ret_doublearr2_tricky1_s()
+#[no_mangle]
+pub extern "C" fn f_ret_doublearr2_tricky1_s() -> DoubleArr2Tricky1 {
+    DoubleArr2Tricky1 { g: [Tricky1 { f: [1.] }, Tricky1 { f: [2.] }] }
+}
+
+#[repr(C)]
+pub struct EmptyStruct {}
+
+#[repr(C)]
+pub struct DoubleArr2Tricky2 {
+    s: EmptyStruct,
+    g: [Tricky1; 2],
+}
+
+// CHECK: define void @f_doublearr2_tricky2_s_arg({ double, double })
+#[no_mangle]
+pub extern "C" fn f_doublearr2_tricky2_s_arg(a: DoubleArr2Tricky2) {}
+
+// CHECK: define { double, double } @f_ret_doublearr2_tricky2_s()
+#[no_mangle]
+pub extern "C" fn f_ret_doublearr2_tricky2_s() -> DoubleArr2Tricky2 {
+    DoubleArr2Tricky2 { s: EmptyStruct {}, g: [Tricky1 { f: [1.] }, Tricky1 { f: [2.] }] }
+}
+
+#[repr(C)]
+pub struct IntDoubleInt {
+    a: i32,
+    b: f64,
+    c: i32,
+}
+
+// CHECK: define void @f_int_double_int_s_arg(%IntDoubleInt* {{.*}}%a)
+#[no_mangle]
+pub extern "C" fn f_int_double_int_s_arg(a: IntDoubleInt) {}
+
+// CHECK: define void @f_ret_int_double_int_s(%IntDoubleInt* {{.*}}sret
+#[no_mangle]
+pub extern "C" fn f_ret_int_double_int_s() -> IntDoubleInt {
+    IntDoubleInt { a: 1, b: 2., c: 3 }
+}
+
+#[repr(C)]
+pub struct CharCharDouble {
+    a: u8,
+    b: u8,
+    c: f64,
+}
+
+// CHECK: define void @f_char_char_double_s_arg([2 x i64])
+#[no_mangle]
+pub extern "C" fn f_char_char_double_s_arg(a: CharCharDouble) {}
+
+// CHECK: define [2 x i64] @f_ret_char_char_double_s()
+#[no_mangle]
+pub extern "C" fn f_ret_char_char_double_s() -> CharCharDouble {
+    CharCharDouble { a: 1, b: 2, c: 3. }
+}
+
+#[repr(C)]
+pub union DoubleU {
+    a: f64,
+}
+
+// CHECK: define void @f_double_u_arg(i64)
+#[no_mangle]
+pub extern "C" fn f_double_u_arg(a: DoubleU) {}
+
+// CHECK: define i64 @f_ret_double_u()
+#[no_mangle]
+pub extern "C" fn f_ret_double_u() -> DoubleU {
+    unsafe { DoubleU { a: 1. } }
+}
diff --git a/src/test/codegen/riscv-abi/riscv64-lp64f-lp64d-abi.rs b/src/test/codegen/riscv-abi/riscv64-lp64f-lp64d-abi.rs
new file mode 100644
index 00000000000..d843331f425
--- /dev/null
+++ b/src/test/codegen/riscv-abi/riscv64-lp64f-lp64d-abi.rs
@@ -0,0 +1,277 @@
+// ignore-tidy-linelength
+// compile-flags: -C no-prepopulate-passes
+// only-riscv64
+// only-linux
+#![crate_type = "lib"]
+
+// CHECK: define void @f_fpr_tracking(float, float, float, float, float, float, float, float, i8 zeroext %i)
+#[no_mangle]
+pub extern "C" fn f_fpr_tracking(
+    a: f32,
+    b: f32,
+    c: f32,
+    d: f32,
+    e: f32,
+    f: f32,
+    g: f32,
+    h: f32,
+    i: u8,
+) {
+}
+
+#[repr(C)]
+pub struct Float {
+    f: f32,
+}
+
+#[repr(C)]
+pub struct FloatFloat {
+    f: f32,
+    g: f32,
+}
+
+// CHECK: define void @f_float_s_arg(float)
+#[no_mangle]
+pub extern "C" fn f_float_s_arg(a: Float) {}
+
+// CHECK: define float @f_ret_float_s()
+#[no_mangle]
+pub extern "C" fn f_ret_float_s() -> Float {
+    Float { f: 1. }
+}
+
+// CHECK: define void @f_float_float_s_arg({ float, float })
+#[no_mangle]
+pub extern "C" fn f_float_float_s_arg(a: FloatFloat) {}
+
+// CHECK: define { float, float } @f_ret_float_float_s()
+#[no_mangle]
+pub extern "C" fn f_ret_float_float_s() -> FloatFloat {
+    FloatFloat { f: 1., g: 2. }
+}
+
+// CHECK: define void @f_float_float_s_arg_insufficient_fprs(float, float, float, float, float, float, float, i64)
+#[no_mangle]
+pub extern "C" fn f_float_float_s_arg_insufficient_fprs(
+    a: f32,
+    b: f32,
+    c: f32,
+    d: f32,
+    e: f32,
+    f: f32,
+    g: f32,
+    h: FloatFloat,
+) {
+}
+
+#[repr(C)]
+pub struct FloatInt8 {
+    f: f32,
+    i: i8,
+}
+
+#[repr(C)]
+pub struct FloatUInt8 {
+    f: f32,
+    i: u8,
+}
+
+#[repr(C)]
+pub struct FloatInt32 {
+    f: f32,
+    i: i32,
+}
+
+#[repr(C)]
+pub struct FloatInt64 {
+    f: f32,
+    i: i64,
+}
+
+// CHECK: define void @f_float_int8_s_arg({ float, i8 })
+#[no_mangle]
+pub extern "C" fn f_float_int8_s_arg(a: FloatInt8) {}
+
+// CHECK: define { float, i8 } @f_ret_float_int8_s()
+#[no_mangle]
+pub extern "C" fn f_ret_float_int8_s() -> FloatInt8 {
+    FloatInt8 { f: 1., i: 2 }
+}
+
+// CHECK: define void @f_float_int32_s_arg({ float, i32 })
+#[no_mangle]
+pub extern "C" fn f_float_int32_s_arg(a: FloatInt32) {}
+
+// CHECK: define { float, i32 } @f_ret_float_int32_s()
+#[no_mangle]
+pub extern "C" fn f_ret_float_int32_s() -> FloatInt32 {
+    FloatInt32 { f: 1., i: 2 }
+}
+
+// CHECK: define void @f_float_uint8_s_arg({ float, i8 })
+#[no_mangle]
+pub extern "C" fn f_float_uint8_s_arg(a: FloatUInt8) {}
+
+// CHECK: define { float, i8 } @f_ret_float_uint8_s()
+#[no_mangle]
+pub extern "C" fn f_ret_float_uint8_s() -> FloatUInt8 {
+    FloatUInt8 { f: 1., i: 2 }
+}
+
+// CHECK: define void @f_float_int64_s_arg({ float, i64 })
+#[no_mangle]
+pub extern "C" fn f_float_int64_s_arg(a: FloatInt64) {}
+
+// CHECK: define { float, i64 } @f_ret_float_int64_s()
+#[no_mangle]
+pub extern "C" fn f_ret_float_int64_s() -> FloatInt64 {
+    FloatInt64 { f: 1., i: 2 }
+}
+
+// CHECK: define void @f_float_int8_s_arg_insufficient_gprs(i32 signext %a, i32 signext %b, i32 signext %c, i32 signext %d, i32 signext %e, i32 signext %f, i32 signext %g, i32 signext %h, i64)
+#[no_mangle]
+pub extern "C" fn f_float_int8_s_arg_insufficient_gprs(
+    a: i32,
+    b: i32,
+    c: i32,
+    d: i32,
+    e: i32,
+    f: i32,
+    g: i32,
+    h: i32,
+    i: FloatInt8,
+) {
+}
+
+// CHECK: define void @f_struct_float_int8_insufficient_fprs(float, float, float, float, float, float, float, float, i64)
+#[no_mangle]
+pub extern "C" fn f_struct_float_int8_insufficient_fprs(
+    a: f32,
+    b: f32,
+    c: f32,
+    d: f32,
+    e: f32,
+    f: f32,
+    g: f32,
+    h: f32,
+    i: FloatInt8,
+) {
+}
+
+#[repr(C)]
+pub struct FloatArr1 {
+    a: [f32; 1],
+}
+
+// CHECK: define void @f_floatarr1_s_arg(float)
+#[no_mangle]
+pub extern "C" fn f_floatarr1_s_arg(a: FloatArr1) {}
+
+// CHECK: define float @f_ret_floatarr1_s()
+#[no_mangle]
+pub extern "C" fn f_ret_floatarr1_s() -> FloatArr1 {
+    FloatArr1 { a: [1.] }
+}
+
+#[repr(C)]
+pub struct FloatArr2 {
+    a: [f32; 2],
+}
+
+// CHECK: define void @f_floatarr2_s_arg({ float, float })
+#[no_mangle]
+pub extern "C" fn f_floatarr2_s_arg(a: FloatArr2) {}
+
+// CHECK: define { float, float } @f_ret_floatarr2_s()
+#[no_mangle]
+pub extern "C" fn f_ret_floatarr2_s() -> FloatArr2 {
+    FloatArr2 { a: [1., 2.] }
+}
+
+#[repr(C)]
+pub struct Tricky1 {
+    f: [f32; 1],
+}
+
+#[repr(C)]
+pub struct FloatArr2Tricky1 {
+    g: [Tricky1; 2],
+}
+
+// CHECK: define void @f_floatarr2_tricky1_s_arg({ float, float })
+#[no_mangle]
+pub extern "C" fn f_floatarr2_tricky1_s_arg(a: FloatArr2Tricky1) {}
+
+// CHECK: define { float, float } @f_ret_floatarr2_tricky1_s()
+#[no_mangle]
+pub extern "C" fn f_ret_floatarr2_tricky1_s() -> FloatArr2Tricky1 {
+    FloatArr2Tricky1 { g: [Tricky1 { f: [1.] }, Tricky1 { f: [2.] }] }
+}
+
+#[repr(C)]
+pub struct EmptyStruct {}
+
+#[repr(C)]
+pub struct FloatArr2Tricky2 {
+    s: EmptyStruct,
+    g: [Tricky1; 2],
+}
+
+// CHECK: define void @f_floatarr2_tricky2_s_arg({ float, float })
+#[no_mangle]
+pub extern "C" fn f_floatarr2_tricky2_s_arg(a: FloatArr2Tricky2) {}
+
+// CHECK: define { float, float } @f_ret_floatarr2_tricky2_s()
+#[no_mangle]
+pub extern "C" fn f_ret_floatarr2_tricky2_s() -> FloatArr2Tricky2 {
+    FloatArr2Tricky2 { s: EmptyStruct {}, g: [Tricky1 { f: [1.] }, Tricky1 { f: [2.] }] }
+}
+
+#[repr(C)]
+pub struct IntFloatInt {
+    a: i32,
+    b: f32,
+    c: i32,
+}
+
+// CHECK: define void @f_int_float_int_s_arg([2 x i64])
+#[no_mangle]
+pub extern "C" fn f_int_float_int_s_arg(a: IntFloatInt) {}
+
+// CHECK: define [2 x i64] @f_ret_int_float_int_s()
+#[no_mangle]
+pub extern "C" fn f_ret_int_float_int_s() -> IntFloatInt {
+    IntFloatInt { a: 1, b: 2., c: 3 }
+}
+
+#[repr(C)]
+pub struct CharCharFloat {
+    a: u8,
+    b: u8,
+    c: f32,
+}
+
+// CHECK: define void @f_char_char_float_s_arg(i64)
+#[no_mangle]
+pub extern "C" fn f_char_char_float_s_arg(a: CharCharFloat) {}
+
+// CHECK: define i64 @f_ret_char_char_float_s()
+#[no_mangle]
+pub extern "C" fn f_ret_char_char_float_s() -> CharCharFloat {
+    CharCharFloat { a: 1, b: 2, c: 3. }
+}
+
+#[repr(C)]
+pub union FloatU {
+    a: f32,
+}
+
+// CHECK: define void @f_float_u_arg(i64)
+#[no_mangle]
+pub extern "C" fn f_float_u_arg(a: FloatU) {}
+
+// CHECK: define i64 @f_ret_float_u()
+#[no_mangle]
+pub extern "C" fn f_ret_float_u() -> FloatU {
+    unsafe { FloatU { a: 1. } }
+}
diff --git a/src/test/ui/abi/struct-enums/struct-return.rs b/src/test/ui/abi/struct-enums/struct-return.rs
index 5930fc4acbb..a3e70bbdb08 100644
--- a/src/test/ui/abi/struct-enums/struct-return.rs
+++ b/src/test/ui/abi/struct-enums/struct-return.rs
@@ -10,13 +10,23 @@ pub struct Quad { a: u64, b: u64, c: u64, d: u64 }
 #[derive(Copy, Clone)]
 pub struct Floats { a: f64, b: u8, c: f64 }
 
+#[repr(C)]
+#[derive(Copy, Clone)]
+pub struct CharCharDouble { a: u8, b: u8, c: f64 }
+
+#[repr(C)]
+#[derive(Copy, Clone)]
+pub struct CharCharFloat { a: u8, b: u8, c: f32 }
+
 mod rustrt {
-    use super::{Floats, Quad};
+    use super::{Floats, Quad, CharCharDouble, CharCharFloat};
 
     #[link(name = "rust_test_helpers", kind = "static")]
     extern {
         pub fn rust_dbg_abi_1(q: Quad) -> Quad;
         pub fn rust_dbg_abi_2(f: Floats) -> Floats;
+        pub fn rust_dbg_abi_3(a: CharCharDouble) -> CharCharDouble;
+        pub fn rust_dbg_abi_4(a: CharCharFloat) -> CharCharFloat;
     }
 }
 
@@ -58,7 +68,47 @@ fn test2() {
 fn test2() {
 }
 
+#[cfg(target_pointer_width = "64")]
+fn test3() {
+    unsafe {
+        let a = CharCharDouble {
+            a: 1,
+            b: 2,
+            c: 3.,
+        };
+        let b = rustrt::rust_dbg_abi_3(a);
+        println!("a: {}", b.a);
+        println!("b: {}", b.b);
+        println!("c: {}", b.c);
+        assert_eq!(b.a, a.a + 1);
+        assert_eq!(b.b, a.b - 1);
+        assert_eq!(b.c, a.c + 1.0);
+    }
+}
+
+#[cfg(target_pointer_width = "32")]
+fn test3() {}
+
+fn test4() {
+    unsafe {
+        let a = CharCharFloat {
+            a: 1,
+            b: 2,
+            c: 3.,
+        };
+        let b = rustrt::rust_dbg_abi_4(a);
+        println!("a: {}", b.a);
+        println!("b: {}", b.b);
+        println!("c: {}", b.c);
+        assert_eq!(b.a, a.a + 1);
+        assert_eq!(b.b, a.b - 1);
+        assert_eq!(b.c, a.c + 1.0);
+    }
+}
+
 pub fn main() {
     test1();
     test2();
+    test3();
+    test4();
 }