Add new EFIAPI ABI

Adds a new ABI for the EFIAPI calls. This ABI should reflect the latest
version of the UEFI specification at the time of commit (UEFI spec 2.8,
URL below). The specification says that for x86_64, we should follow the
win64 ABI, while on all other supported platforms (ia32, itanium, arm,
arm64 and risc-v), we should follow the C ABI.

To simplify the implementation, we will simply follow the C ABI on all
platforms except x86_64, even those technically unsupported by the UEFI
specification.

https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf

Author: roblabla

src/librustc/ich/impls_syntax.rs

@@ -80,6 +80,7 @@ impl_stable_hash_for!(enum ::rustc_target::spec::abi::Abi {
     Msp430Interrupt,
     X86Interrupt,
     AmdGpuKernel,
+    EfiApi,
     Rust,
     C,
     System,

src/librustc/ty/layout.rs

@@ -2596,6 +2596,7 @@ where
 
             // It's the ABI's job to select this, not ours.
             System => bug!("system abi should be selected elsewhere"),
+            EfiApi => bug!("eficall abi should be selected elsewhere"),
 
             Stdcall => Conv::X86Stdcall,
             Fastcall => Conv::X86Fastcall,

src/librustc_target/spec/abi.rs

@@ -21,6 +21,7 @@ pub enum Abi {
     Msp430Interrupt,
     X86Interrupt,
     AmdGpuKernel,
+    EfiApi,
 
     // Multiplatform / generic ABIs
     Rust,
@@ -58,6 +59,7 @@ const AbiDatas: &[AbiData] = &[
     AbiData {abi: Abi::Msp430Interrupt, name: "msp430-interrupt", generic: false },
     AbiData {abi: Abi::X86Interrupt, name: "x86-interrupt", generic: false },
     AbiData {abi: Abi::AmdGpuKernel, name: "amdgpu-kernel", generic: false },
+    AbiData {abi: Abi::EfiApi, name: "efiapi", generic: false },
 
     // Cross-platform ABIs
     AbiData {abi: Abi::Rust, name: "Rust", generic: true },

src/librustc_target/spec/mod.rs

@@ -905,6 +905,13 @@ impl Target {
                     abi
                 }
             },
+            Abi::EfiApi => {
+                if self.arch != "x86_64" {
+                    Abi::Win64
+                } else {
+                    Abi::C
+                }
+            },
             abi => abi
         }
     }

src/libsyntax/feature_gate/active.rs

@@ -531,6 +531,9 @@ declare_features! (
     /// Non-object safe trait objects safe to use but cannot be created in safe rust
     (active, object_safe_for_dispatch, "1.40.0", Some(43561), None),
 
+    /// Allows using the `efiapi` ABI.
+    (active, abi_efiapi, "1.40.0", Some(1), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------

src/libsyntax/feature_gate/check.rs

@@ -234,6 +234,10 @@ impl<'a> PostExpansionVisitor<'a> {
                 gate_feature_post!(&self, abi_amdgpu_kernel, span,
                                    "amdgpu-kernel ABI is experimental and subject to change");
             },
+            Abi::EfiApi => {
+                gate_feature_post!(&self, abi_efiapi, span,
+                                   "efiapi ABI is experimental and subject to change");
+            },
             // Stable
             Abi::Cdecl |
             Abi::Stdcall |

src/libsyntax_pos/symbol.rs

@@ -110,6 +110,7 @@ symbols! {
         aarch64_target_feature,
         abi,
         abi_amdgpu_kernel,
+        abi_efiapi,
         abi_msp430_interrupt,
         abi_ptx,
         abi_sysv64,

src/test/codegen/abi-efiapi.rs

@@ -0,0 +1,20 @@
+// Checks if the correct annotation for the efiapi ABI is passed to llvm.
+
+// compile-flags: -C no-prepopulate-passes
+
+#![crate_type = "lib"]
+#![feature(abi_efiapi)]
+
+// CHECK: define win64 i64 @has_efiapi
+#[no_mangle]
+#[cfg(target_arch = "x86_64")]
+pub extern "efiapi" fn has_efiapi(a: i64) -> i64 {
+    a * 2
+}
+
+// CHECK: define c i64 @has_efiapi
+#[no_mangle]
+#[cfg(not(target_arch = "x86_64"))]
+pub extern "efiapi" fn has_efiapi(a: i64) -> i64 {
+    a * 2
+}

src/test/ui/codemap_tests/unicode.stderr

@@ -4,7 +4,7 @@ error[E0703]: invalid ABI: found `路濫狼á́́`
 LL | extern "路濫狼á́́" fn foo() {}
    |        ^^^^^^^^^ invalid ABI
    |
-   = help: valid ABIs: cdecl, stdcall, fastcall, vectorcall, thiscall, aapcs, win64, sysv64, ptx-kernel, msp430-interrupt, x86-interrupt, amdgpu-kernel, Rust, C, system, rust-intrinsic, rust-call, platform-intrinsic, unadjusted
+   = help: valid ABIs: cdecl, stdcall, fastcall, vectorcall, thiscall, aapcs, win64, sysv64, ptx-kernel, msp430-interrupt, x86-interrupt, amdgpu-kernel, efiapi, Rust, C, system, rust-intrinsic, rust-call, platform-intrinsic, unadjusted
 
 error: aborting due to previous error
 

src/test/ui/feature-gates/feature-gate-abi.rs

@@ -7,6 +7,7 @@
 // gate-test-abi_ptx
 // gate-test-abi_x86_interrupt
 // gate-test-abi_amdgpu_kernel
+// gate-test-abi_efiapi
 
 // Functions
 extern "rust-intrinsic" fn f1() {} //~ ERROR intrinsics are subject to change
@@ -20,6 +21,7 @@ extern "ptx-kernel" fn f6() {} //~ ERROR PTX ABIs are experimental and subject t
 extern "x86-interrupt" fn f7() {} //~ ERROR x86-interrupt ABI is experimental
 extern "thiscall" fn f8() {} //~ ERROR thiscall is experimental and subject to change
 extern "amdgpu-kernel" fn f9() {} //~ ERROR amdgpu-kernel ABI is experimental and subject to change
+extern "efiapi" fn f10() {} //~ ERROR efiapi ABI is experimental and subject to change
 
 // Methods in trait definition
 trait Tr {
@@ -34,6 +36,7 @@ trait Tr {
     extern "x86-interrupt" fn m7(); //~ ERROR x86-interrupt ABI is experimental
     extern "thiscall" fn m8(); //~ ERROR thiscall is experimental and subject to change
     extern "amdgpu-kernel" fn m9(); //~ ERROR amdgpu-kernel ABI is experimental and subject to change
+    extern "efiapi" fn m10(); //~ ERROR efiapi ABI is experimental and subject to change
 
     extern "vectorcall" fn dm3() {} //~ ERROR vectorcall is experimental and subject to change
     extern "rust-call" fn dm4() {} //~ ERROR rust-call ABI is subject to change
@@ -42,6 +45,7 @@ trait Tr {
     extern "x86-interrupt" fn dm7() {} //~ ERROR x86-interrupt ABI is experimental
     extern "thiscall" fn dm8() {} //~ ERROR thiscall is experimental and subject to change
     extern "amdgpu-kernel" fn dm9() {} //~ ERROR amdgpu-kernel ABI is experimental and subject to change
+    extern "efiapi" fn dm10() {} //~ ERROR efiapi ABI is experimental and subject to change
 }
 
 struct S;
@@ -59,6 +63,7 @@ impl Tr for S {
     extern "x86-interrupt" fn m7() {} //~ ERROR x86-interrupt ABI is experimental
     extern "thiscall" fn m8() {} //~ ERROR thiscall is experimental and subject to change
     extern "amdgpu-kernel" fn m9() {} //~ ERROR amdgpu-kernel ABI is experimental and subject to change
+    extern "efiapi" fn m10() {} //~ ERROR efiapi ABI is experimental and subject to change
 }
 
 // Methods in inherent impl
@@ -74,6 +79,7 @@ impl S {
     extern "x86-interrupt" fn im7() {} //~ ERROR x86-interrupt ABI is experimental
     extern "thiscall" fn im8() {} //~ ERROR thiscall is experimental and subject to change
     extern "amdgpu-kernel" fn im9() {} //~ ERROR amdgpu-kernel ABI is experimental and subject to change
+    extern "efiapi" fn im10() {} //~ ERROR efiapi ABI is experimental and subject to change
 }
 
 // Function pointer types
@@ -86,6 +92,7 @@ type A6 = extern "ptx-kernel" fn (); //~ ERROR PTX ABIs are experimental and sub
 type A7 = extern "x86-interrupt" fn(); //~ ERROR x86-interrupt ABI is experimental
 type A8 = extern "thiscall" fn(); //~ ERROR thiscall is experimental and subject to change
 type A9 = extern "amdgpu-kernel" fn(); //~ ERROR amdgpu-kernel ABI is experimental and subject to change
+type A10 = extern "efiapi" fn(); //~ ERROR efiapi ABI is experimental and subject to change
 
 // Foreign modules
 extern "rust-intrinsic" {} //~ ERROR intrinsics are subject to change
@@ -97,5 +104,6 @@ extern "ptx-kernel" {} //~ ERROR PTX ABIs are experimental and subject to change
 extern "x86-interrupt" {} //~ ERROR x86-interrupt ABI is experimental
 extern "thiscall" {} //~ ERROR thiscall is experimental and subject to change
 extern "amdgpu-kernel" {} //~ ERROR amdgpu-kernel ABI is experimental and subject to change
+extern "efiapi" {} //~ ERROR efiapi ABI is experimental and subject to change
 
 fn main() {}