Rollup merge of #81455 - Amanieu:aarch64_ilp32, r=sanxiyn

Add AArch64 big-endian and ILP32 targets

This PR adds 3 new AArch64 targets:
- `aarch64_be-unknown-linux-gnu`
- `aarch64-unknown-linux-gnu_ilp32`
- `aarch64_be-unknown-linux-gnu_ilp32`

It also fixes some ABI issues on big-endian ARM and AArch64.

compiler/rustc_codegen_llvm/src/va_arg.rs

@@ -105,7 +105,6 @@ fn emit_aapcs_va_arg(
     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_eq!(bx.tcx().sess.target.endian, 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 {
@@ -144,9 +143,14 @@ fn emit_aapcs_va_arg(
     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);
+    let mut reg_addr = in_reg.gep(top, &[reg_off_v]);
+    if bx.tcx().sess.target.endian == Endian::Big && layout.size.bytes() != slot_size {
+        // On big-endian systems the value is right-aligned in its slot.
+        let offset = bx.const_i32((slot_size - layout.size.bytes()) as i32);
+        reg_addr = in_reg.gep(reg_addr, &[offset]);
+    }
+    let reg_addr = in_reg.bitcast(reg_addr, bx.cx.type_ptr_to(layout.llvm_type(bx)));
+    let reg_value = in_reg.load(reg_addr, layout.align.abi);
     in_reg.br(&end.llbb());
 
     // On Stack block

compiler/rustc_target/src/abi/call/aarch64.rs

@@ -40,17 +40,7 @@ where
     let size = ret.layout.size;
     let bits = size.bits();
     if bits <= 128 {
-        let unit = if bits <= 8 {
-            Reg::i8()
-        } else if bits <= 16 {
-            Reg::i16()
-        } else if bits <= 32 {
-            Reg::i32()
-        } else {
-            Reg::i64()
-        };
-
-        ret.cast_to(Uniform { unit, total: size });
+        ret.cast_to(Uniform { unit: Reg::i64(), total: size });
         return;
     }
     ret.make_indirect();
@@ -72,17 +62,7 @@ where
     let size = arg.layout.size;
     let bits = size.bits();
     if bits <= 128 {
-        let unit = if bits <= 8 {
-            Reg::i8()
-        } else if bits <= 16 {
-            Reg::i16()
-        } else if bits <= 32 {
-            Reg::i32()
-        } else {
-            Reg::i64()
-        };
-
-        arg.cast_to(Uniform { unit, total: size });
+        arg.cast_to(Uniform { unit: Reg::i64(), total: size });
         return;
     }
     arg.make_indirect();

compiler/rustc_target/src/abi/call/arm.rs

@@ -45,14 +45,7 @@ where
     let size = ret.layout.size;
     let bits = size.bits();
     if bits <= 32 {
-        let unit = if bits <= 8 {
-            Reg::i8()
-        } else if bits <= 16 {
-            Reg::i16()
-        } else {
-            Reg::i32()
-        };
-        ret.cast_to(Uniform { unit, total: size });
+        ret.cast_to(Uniform { unit: Reg::i32(), total: size });
         return;
     }
     ret.make_indirect();

compiler/rustc_target/src/spec/aarch64_be_unknown_linux_gnu.rs

@@ -0,0 +1,20 @@
+use crate::abi::Endian;
+use crate::spec::{Target, TargetOptions};
+
+pub fn target() -> Target {
+    let mut base = super::linux_gnu_base::opts();
+    base.max_atomic_width = Some(128);
+
+    Target {
+        llvm_target: "aarch64_be-unknown-linux-gnu".to_string(),
+        pointer_width: 64,
+        data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
+        arch: "aarch64".to_string(),
+        options: TargetOptions {
+            unsupported_abis: super::arm_base::unsupported_abis(),
+            mcount: "\u{1}_mcount".to_string(),
+            endian: Endian::Big,
+            ..base
+        },
+    }
+}

compiler/rustc_target/src/spec/aarch64_be_unknown_linux_gnu_ilp32.rs

@@ -0,0 +1,20 @@
+use crate::abi::Endian;
+use crate::spec::{Target, TargetOptions};
+
+pub fn target() -> Target {
+    let mut base = super::linux_gnu_base::opts();
+    base.max_atomic_width = Some(128);
+
+    Target {
+        llvm_target: "aarch64_be-unknown-linux-gnu_ilp32".to_string(),
+        pointer_width: 32,
+        data_layout: "E-m:e-p:32:32-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
+        arch: "aarch64".to_string(),
+        options: TargetOptions {
+            unsupported_abis: super::arm_base::unsupported_abis(),
+            mcount: "\u{1}_mcount".to_string(),
+            endian: Endian::Big,
+            ..base
+        },
+    }
+}

compiler/rustc_target/src/spec/aarch64_unknown_linux_gnu_ilp32.rs

@@ -0,0 +1,18 @@
+use crate::spec::{Target, TargetOptions};
+
+pub fn target() -> Target {
+    let mut base = super::linux_gnu_base::opts();
+    base.max_atomic_width = Some(128);
+
+    Target {
+        llvm_target: "aarch64-unknown-linux-gnu_ilp32".to_string(),
+        pointer_width: 32,
+        data_layout: "e-m:e-p:32:32-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
+        arch: "aarch64".to_string(),
+        options: TargetOptions {
+            unsupported_abis: super::arm_base::unsupported_abis(),
+            mcount: "\u{1}_mcount".to_string(),
+            ..base
+        },
+    }
+}

compiler/rustc_target/src/spec/mod.rs

@@ -808,6 +808,10 @@ supported_targets! {
     ("mipsel-sony-psp", mipsel_sony_psp),
     ("mipsel-unknown-none", mipsel_unknown_none),
     ("thumbv4t-none-eabi", thumbv4t_none_eabi),
+
+    ("aarch64_be-unknown-linux-gnu", aarch64_be_unknown_linux_gnu),
+    ("aarch64-unknown-linux-gnu_ilp32", aarch64_unknown_linux_gnu_ilp32),
+    ("aarch64_be-unknown-linux-gnu_ilp32", aarch64_be_unknown_linux_gnu_ilp32),
 }
 
 /// Everything `rustc` knows about how to compile for a specific target.