Tie extern "llvm-intrinsics" and llvm.* symbol names together

compiler/rustc_monomorphize/src/mono_checks/abi_check.rs

@@ -3,6 +3,7 @@
 use rustc_abi::{BackendRepr, CanonAbi, ExternAbi, RegKind, X86Call};
 use rustc_hir::{CRATE_HIR_ID, HirId};
 use rustc_middle::mir::{self, Location, traversal};
+use rustc_middle::span_bug;
 use rustc_middle::ty::layout::{FnAbiRequest, codegen_handle_fn_abi_err};
 use rustc_middle::ty::{self, Instance, InstanceKind, Ty, TyCtxt};
 use rustc_span::def_id::DefId;
@@ -212,12 +213,44 @@ fn check_call_site_abi<'tcx>(
     loc: impl Fn() -> (Span, HirId) + Copy,
 ) {
     let extern_abi = callee.fn_sig(tcx).abi();
-    if extern_abi.is_rustic_abi() || extern_abi == ExternAbi::LlvmIntrinsic {
+    if extern_abi.is_rustic_abi() {
         // We directly handle the soundness of Rust ABIs -- so let's skip the majority of
         // call sites to avoid a perf regression.
+        return;
+    }
+    if extern_abi == ExternAbi::LlvmIntrinsic {
         // We disable all checks for the llvm-intrinsic ABI to allow linking to arbitrary
         // LLVM intrinsics
-        return;
+        let typing_env = ty::TypingEnv::fully_monomorphized();
+        match *callee.kind() {
+            ty::FnDef(def_id, args) => {
+                let instance = ty::Instance::expect_resolve(
+                    tcx,
+                    typing_env,
+                    def_id,
+                    args.no_bound_vars().unwrap(),
+                    DUMMY_SP,
+                );
+                let InstanceKind::LlvmIntrinsic(..) = instance.def else {
+                    span_bug!(
+                        loc().0,
+                        "`extern \"llvm-intrinsic\"` may only be used for LLVM intrinsics"
+                    );
+                };
+                let name = tcx
+                    .codegen_fn_attrs(def_id)
+                    .symbol_name
+                    .expect("llvm-intrinsic must be foreign function");
+                assert!(
+                    name.as_str().starts_with("llvm."),
+                    "llvm-intrinsic name must start with llvm."
+                );
+                return;
+            }
+            _ => {
+                span_bug!(loc().0, "`extern \"llvm-intrinsic\"` may only be used for direct calls")
+            }
+        };
     }
     let typing_env = ty::TypingEnv::fully_monomorphized();
     let callee_abi = match *callee.kind() {
@@ -250,8 +283,15 @@ fn check_call_site_abi<'tcx>(
                 DUMMY_SP,
             );
             if let InstanceKind::LlvmIntrinsic(..) = instance.def {
-                // LLVM intrinsics don't have an ABI, so there is nothing to check.
-                return;
+                let name = tcx
+                    .codegen_fn_attrs(def_id)
+                    .symbol_name
+                    .expect("llvm-intrinsic must be foreign function");
+                // llvm.wasm.throw is the only unwinding LLVM intrinsic we have.
+                // FIXME maybe replace with inline asm?
+                if name.as_str() != "llvm.wasm.throw" {
+                    span_bug!(loc().0, "llvm.* function must use `extern \"llvm-intrinsic\"`");
+                }
             }
             match tcx.fn_abi_of_instance(typing_env.as_query_input((instance, ty::List::empty()))) {
                 Ok(callee_abi) => callee_abi,

tests/codegen-llvm/call-llvm-intrinsics.rs

@@ -14,7 +14,7 @@ impl Drop for A {
     }
 }
 
-extern "C" {
+extern "llvm-intrinsic" {
     #[link_name = "llvm.sqrt.f32"]
     fn sqrt(x: f32) -> f32;
 }

tests/codegen-llvm/loongarch-abi/call-llvm-intrinsics.rs

@@ -13,7 +13,7 @@ impl Drop for A {
     }
 }
 
-extern "C" {
+extern "llvm-intrinsic" {
     #[link_name = "llvm.sqrt.f32"]
     fn sqrt(x: f32) -> f32;
 }

tests/codegen-llvm/riscv-abi/call-llvm-intrinsics.rs

@@ -15,7 +15,7 @@
 extern crate minicore;
 use minicore::*;
 
-extern "C" {
+extern "llvm-intrinsic" {
     #[link_name = "llvm.sqrt.f32"]
     fn sqrt(x: f32) -> f32;
 }

tests/run-make/simd-ffi/simd.rs

@@ -10,7 +10,7 @@
 #[repr(simd)]
 pub struct f32x4([f32; 4]);
 
-extern "C" {
+extern "llvm-intrinsic" {
     #[link_name = "llvm.sqrt.v4f32"]
     fn vsqrt(x: f32x4) -> f32x4;
 }
@@ -23,7 +23,7 @@ pub fn foo(x: f32x4) -> f32x4 {
 #[repr(simd)]
 pub struct i32x4([i32; 4]);
 
-extern "C" {
+extern "llvm-intrinsic" {
     // _mm_sll_epi32
     #[cfg(all(any(target_arch = "x86", target_arch = "x86-64"), target_feature = "sse2"))]
     #[link_name = "llvm.x86.sse2.psll.d"]

tests/run-make/wasm-exceptions-nostd/src/panicking.rs

@@ -2,7 +2,7 @@
 fn eh_personality() {}
 
 mod internal {
-    extern "C" {
+    extern "C-unwind" {
         #[link_name = "llvm.wasm.throw"]
         pub fn wasm_throw(tag: i32, ptr: *mut u8) -> !;
     }

tests/ui/feature-gates/link-llvm-intrinsics-enabled.rs

@@ -4,7 +4,7 @@
 #![allow(dead_code)]
 #![feature(link_llvm_intrinsics)]
 
-extern "C" {
+extern "llvm-intrinsic" {
     #[link_name = "llvm.sqrt.f32"]
     fn sqrt(x: f32) -> f32;
 }

tests/ui/scalable-vectors/async.rs

@@ -17,7 +17,7 @@ pub struct svint32_t(i32);
 
 #[target_feature(enable = "sve")]
 pub unsafe fn svdup_n_s32(op: i32) -> svint32_t {
-    extern "C" {
+    extern "llvm-intrinsic" {
         #[cfg_attr(target_arch = "aarch64", link_name = "llvm.aarch64.sve.dup.x.nxv4i32")]
         fn _svdup_n_s32(op: i32) -> svint32_t;
     }

tests/ui/scalable-vectors/closure-capture.rs

@@ -16,7 +16,7 @@ pub struct svint32_t(i32);
 #[inline(never)]
 #[target_feature(enable = "sve")]
 pub unsafe fn svdup_n_s32(op: i32) -> svint32_t {
-    extern "C" {
+    extern "llvm-intrinsic" {
         #[cfg_attr(target_arch = "aarch64", link_name = "llvm.aarch64.sve.dup.x.nxv4i32")]
         fn _svdup_n_s32(op: i32) -> svint32_t;
     }
@@ -26,7 +26,7 @@ pub unsafe fn svdup_n_s32(op: i32) -> svint32_t {
 #[inline]
 #[target_feature(enable = "sve,sve2")]
 pub unsafe fn svxar_n_s32<const IMM3: i32>(op1: svint32_t, op2: svint32_t) -> svint32_t {
-    extern "C" {
+    extern "llvm-intrinsic" {
         #[cfg_attr(target_arch = "aarch64", link_name = "llvm.aarch64.sve.xar.nxv4i32")]
         fn _svxar_n_s32(op1: svint32_t, op2: svint32_t, imm3: i32) -> svint32_t;
     }

tests/ui/scalable-vectors/copy-clone.rs

@@ -9,7 +9,7 @@ pub struct svint32_t(i32);
 
 #[target_feature(enable = "sve")]
 pub unsafe fn svdup_n_s32(op: i32) -> svint32_t {
-    extern "C" {
+    extern "llvm-intrinsic" {
         #[cfg_attr(target_arch = "aarch64", link_name = "llvm.aarch64.sve.dup.x.nxv4i32")]
         fn _svdup_n_s32(op: i32) -> svint32_t;
 //~^ WARN: `extern` block uses type `svint32_t`, which is not FFI-safe

tests/ui/scalable-vectors/debuginfo-does-not-spill.rs

@@ -22,7 +22,7 @@ pub struct svbool4_t(bool);
 impl std::convert::Into<svbool_t> for svbool4_t {
     #[inline(always)]
     fn into(self) -> svbool_t {
-        unsafe extern "C" {
+        unsafe extern "llvm-intrinsic" {
             #[link_name = "llvm.aarch64.sve.convert.to.svbool.nxv4i1"]
             fn convert_to_svbool(b: svbool4_t) -> svbool_t;
         }
@@ -31,7 +31,7 @@ impl std::convert::Into<svbool_t> for svbool4_t {
 }
 
 pub fn svwhilelt_b32_u64(op1: u64, op2: u64) -> svbool_t {
-    unsafe extern "C" {
+    unsafe extern "llvm-intrinsic" {
         #[link_name = "llvm.aarch64.sve.whilelo.nxv4i1.u64"]
         fn _svwhilelt_b32_u64(op1: u64, op2: u64) -> svbool4_t;
     }

tests/ui/scalable-vectors/require-target-feature.rs

@@ -25,7 +25,7 @@ impl Copy for svint32_t {}
 #[inline(never)]
 #[target_feature(enable = "sve")]
 pub unsafe fn svdup_n_s32(op: i32) -> svint32_t {
-    extern "C" {
+    extern "llvm-intrinsic" {
         #[cfg_attr(target_arch = "aarch64", link_name = "llvm.aarch64.sve.dup.x.nxv4i32")]
         fn _svdup_n_s32(op: i32) -> svint32_t;
 //~^ WARN: `extern` block uses type `svint32_t`, which is not FFI-safe

tests/ui/scalable-vectors/value-type.rs

@@ -15,7 +15,7 @@ pub struct svint32_t(i32);
 
 #[target_feature(enable = "sve")]
 pub unsafe fn svdup_n_s32(op: i32) -> svint32_t {
-    extern "C" {
+    extern "llvm-intrinsic" {
         #[cfg_attr(target_arch = "aarch64", link_name = "llvm.aarch64.sve.dup.x.nxv4i32")]
         fn _svdup_n_s32(op: i32) -> svint32_t;
 //~^ WARN: `extern` block uses type `svint32_t`, which is not FFI-safe