compiler: simplify TargetOptions ABI functions

`adjust_abi` is not needed and `is_abi_supported` can be a 1-liner.

Author: workingjubilee

compiler/rustc_target/src/callconv/mod.rs

@@ -697,7 +697,6 @@ impl<'a, Ty> FnAbi<'a, Ty> {
             "sparc" => sparc::compute_abi_info(cx, self),
             "sparc64" => sparc64::compute_abi_info(cx, self),
             "nvptx64" => {
-                let abi = cx.target_spec().adjust_abi(abi, self.c_variadic);
                 if abi == ExternAbi::PtxKernel || abi == ExternAbi::GpuKernel {
                     nvptx64::compute_ptx_kernel_abi_info(cx, self)
                 } else {

compiler/rustc_target/src/spec/mod.rs

@@ -2915,114 +2915,9 @@ impl DerefMut for Target {
 }
 
 impl Target {
-    /// Given a function ABI, turn it into the correct ABI for this target.
-    pub fn adjust_abi(&self, abi: ExternAbi, c_variadic: bool) -> ExternAbi {
-        use ExternAbi::*;
-        match abi {
-            // On Windows, `extern "system"` behaves like msvc's `__stdcall`.
-            // `__stdcall` only applies on x86 and on non-variadic functions:
-            // https://learn.microsoft.com/en-us/cpp/cpp/stdcall?view=msvc-170
-            System { unwind } => {
-                if self.is_like_windows && self.arch == "x86" && !c_variadic {
-                    Stdcall { unwind }
-                } else {
-                    C { unwind }
-                }
-            }
-
-            EfiApi => {
-                if self.arch == "arm" {
-                    Aapcs { unwind: false }
-                } else if self.arch == "x86_64" {
-                    Win64 { unwind: false }
-                } else {
-                    C { unwind: false }
-                }
-            }
-
-            // See commentary in `is_abi_supported`.
-            Stdcall { unwind } | Thiscall { unwind } | Fastcall { unwind } => {
-                if self.arch == "x86" { abi } else { C { unwind } }
-            }
-            Vectorcall { unwind } => {
-                if ["x86", "x86_64"].contains(&&*self.arch) {
-                    abi
-                } else {
-                    C { unwind }
-                }
-            }
-
-            // The Windows x64 calling convention we use for `extern "Rust"`
-            // <https://learn.microsoft.com/en-us/cpp/build/x64-software-conventions#register-volatility-and-preservation>
-            // expects the callee to save `xmm6` through `xmm15`, but `PreserveMost`
-            // (that we use by default for `extern "rust-cold"`) doesn't save any of those.
-            // So to avoid bloating callers, just use the Rust convention here.
-            RustCold if self.is_like_windows && self.arch == "x86_64" => Rust,
-
-            abi => abi,
-        }
-    }
-
     pub fn is_abi_supported(&self, abi: ExternAbi) -> bool {
-        use ExternAbi::*;
-        match abi {
-            Rust | C { .. } | System { .. } | RustCall | Unadjusted | Cdecl { .. } | RustCold => {
-                true
-            }
-            EfiApi => {
-                ["arm", "aarch64", "riscv32", "riscv64", "x86", "x86_64"].contains(&&self.arch[..])
-            }
-            X86Interrupt => ["x86", "x86_64"].contains(&&self.arch[..]),
-            Aapcs { .. } => "arm" == self.arch,
-            CCmseNonSecureCall | CCmseNonSecureEntry => {
-                ["thumbv8m.main-none-eabi", "thumbv8m.main-none-eabihf", "thumbv8m.base-none-eabi"]
-                    .contains(&&self.llvm_target[..])
-            }
-            Win64 { .. } | SysV64 { .. } => self.arch == "x86_64",
-            PtxKernel => self.arch == "nvptx64",
-            GpuKernel => ["amdgpu", "nvptx64"].contains(&&self.arch[..]),
-            Msp430Interrupt => self.arch == "msp430",
-            RiscvInterruptM | RiscvInterruptS => ["riscv32", "riscv64"].contains(&&self.arch[..]),
-            AvrInterrupt | AvrNonBlockingInterrupt => self.arch == "avr",
-            Thiscall { .. } => self.arch == "x86",
-            // On windows these fall-back to platform native calling convention (C) when the
-            // architecture is not supported.
-            //
-            // This is I believe a historical accident that has occurred as part of Microsoft
-            // striving to allow most of the code to "just" compile when support for 64-bit x86
-            // was added and then later again, when support for ARM architectures was added.
-            //
-            // This is well documented across MSDN. Support for this in Rust has been added in
-            // #54576. This makes much more sense in context of Microsoft's C++ than it does in
-            // Rust, but there isn't much leeway remaining here to change it back at the time this
-            // comment has been written.
-            //
-            // Following are the relevant excerpts from the MSDN documentation.
-            //
-            // > The __vectorcall calling convention is only supported in native code on x86 and
-            // x64 processors that include Streaming SIMD Extensions 2 (SSE2) and above.
-            // > ...
-            // > On ARM machines, __vectorcall is accepted and ignored by the compiler.
-            //
-            // -- https://docs.microsoft.com/en-us/cpp/cpp/vectorcall?view=msvc-160
-            //
-            // > On ARM and x64 processors, __stdcall is accepted and ignored by the compiler;
-            //
-            // -- https://docs.microsoft.com/en-us/cpp/cpp/stdcall?view=msvc-160
-            //
-            // > In most cases, keywords or compiler switches that specify an unsupported
-            // > convention on a particular platform are ignored, and the platform default
-            // > convention is used.
-            //
-            // -- https://docs.microsoft.com/en-us/cpp/cpp/argument-passing-and-naming-conventions
-            Stdcall { .. } | Fastcall { .. } | Vectorcall { .. } if self.is_like_windows => true,
-            // Outside of Windows we want to only support these calling conventions for the
-            // architectures for which these calling conventions are actually well defined.
-            Stdcall { .. } | Fastcall { .. } if self.arch == "x86" => true,
-            Vectorcall { .. } if ["x86", "x86_64"].contains(&&self.arch[..]) => true,
-            // Reject these calling conventions everywhere else.
-            Stdcall { .. } | Fastcall { .. } | Vectorcall { .. } => false,
-        }
+        let abi_map = AbiMap::from_target(self);
+        abi_map.canonize_abi(abi, false).is_mapped()
     }
 
     /// Minimum integer size in bits that this target can perform atomic