From a07bd236bdb47d165c9c7f62e35e2a9a3d773ad6 Mon Sep 17 00:00:00 2001
From: WANG Rui <wangrui@loongson.cn>
Date: Thu, 13 Nov 2025 23:51:01 +0800
Subject: [PATCH] rustc_target: Add `efiapi` ABI support for LoongArch

This commit adds basic `efiapi` ABI support for LoongArch by recognizing
`extern "efiapi"` in the ABI map and inline asm clobber handling, and
mapping it to the C calling convention.

This change is intentionally submitted ahead of the full LoongArch UEFI
target support. While UEFI binaries are ultimately produced as PE images,
LoongArch UEFI applications can already be developed by building ELF
objects, applying relocation fixups, and converting them to PE in a
later step. For such workflows, having `efiapi` properly recognized by
the compiler is a prerequisite, even without a dedicated UEFI target.

Landing this ABI support early helps unblock LoongArch UEFI application
and driver development, and allows the remaining UEFI-specific pieces to
be introduced incrementally in follow-up patches.

MCP: https://github.com/rust-lang/compiler-team/issues/953
---
 compiler/rustc_target/src/asm/mod.rs      | 4 ++--
 compiler/rustc_target/src/spec/abi_map.rs | 7 ++++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/compiler/rustc_target/src/asm/mod.rs b/compiler/rustc_target/src/asm/mod.rs
index 05b24d7109481..0078866ab9503 100644
--- a/compiler/rustc_target/src/asm/mod.rs
+++ b/compiler/rustc_target/src/asm/mod.rs
@@ -997,8 +997,8 @@ impl InlineAsmClobberAbi {
                 _ => Err(&["C", "system"]),
             },
             InlineAsmArch::LoongArch32 | InlineAsmArch::LoongArch64 => match name {
-                "C" | "system" => Ok(InlineAsmClobberAbi::LoongArch),
-                _ => Err(&["C", "system"]),
+                "C" | "system" | "efiapi" => Ok(InlineAsmClobberAbi::LoongArch),
+                _ => Err(&["C", "system", "efiapi"]),
             },
             InlineAsmArch::PowerPC | InlineAsmArch::PowerPC64 => match name {
                 "C" | "system" => Ok(if target.abi == Abi::Spe {
diff --git a/compiler/rustc_target/src/spec/abi_map.rs b/compiler/rustc_target/src/spec/abi_map.rs
index 8126227d80e48..d7fc18cd3761e 100644
--- a/compiler/rustc_target/src/spec/abi_map.rs
+++ b/compiler/rustc_target/src/spec/abi_map.rs
@@ -56,6 +56,7 @@ impl AbiMap {
                 ArmVer::Other
             }),
             Arch::Avr => ArchKind::Avr,
+            Arch::LoongArch32 | Arch::LoongArch64 => ArchKind::LoongArch,
             Arch::Msp430 => ArchKind::Msp430,
             Arch::Nvptx64 => ArchKind::Nvptx,
             Arch::RiscV32 | Arch::RiscV64 => ArchKind::Riscv,
@@ -108,7 +109,10 @@ impl AbiMap {
 
             (ExternAbi::EfiApi, ArchKind::Arm(..)) => CanonAbi::Arm(ArmCall::Aapcs),
             (ExternAbi::EfiApi, ArchKind::X86_64) => CanonAbi::X86(X86Call::Win64),
-            (ExternAbi::EfiApi, ArchKind::Aarch64 | ArchKind::Riscv | ArchKind::X86) => CanonAbi::C,
+            (
+                ExternAbi::EfiApi,
+                ArchKind::Aarch64 | ArchKind::LoongArch | ArchKind::Riscv | ArchKind::X86,
+            ) => CanonAbi::C,
             (ExternAbi::EfiApi, _) => return AbiMapping::Invalid,
 
             /* arm */
@@ -196,6 +200,7 @@ enum ArchKind {
     Amdgpu,
     Arm(ArmVer),
     Avr,
+    LoongArch,
     Msp430,
     Nvptx,
     Riscv,