Avoid computing function type for intrinsic instances

Author: bjorn3

compiler/rustc_codegen_gcc/src/intrinsic/mod.rs

@@ -23,7 +23,7 @@ use rustc_codegen_ssa::traits::{
 use rustc_middle::bug;
 #[cfg(feature = "master")]
 use rustc_middle::ty::layout::FnAbiOf;
-use rustc_middle::ty::layout::{HasTypingEnv, LayoutOf};
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, Instance, Ty};
 use rustc_span::{Span, Symbol, sym};
 use rustc_target::callconv::{ArgAbi, PassMode};
@@ -205,15 +205,10 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tc
         span: Span,
     ) -> Result<(), Instance<'tcx>> {
         let tcx = self.tcx;
-        let callee_ty = instance.ty(tcx, self.typing_env());
 
-        let (def_id, fn_args) = match *callee_ty.kind() {
-            ty::FnDef(def_id, fn_args) => (def_id, fn_args),
-            _ => bug!("expected fn item type, found {}", callee_ty),
-        };
-
-        let name = tcx.item_name(def_id);
+        let name = tcx.item_name(instance.def_id());
         let name_str = name.as_str();
+        let fn_args = instance.args;
 
         let simple = get_simple_intrinsic(self, name);
         let simple_func = get_simple_function(self, name);

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -169,13 +169,9 @@ impl<'ll, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
         span: Span,
     ) -> Result<(), ty::Instance<'tcx>> {
         let tcx = self.tcx;
-        let callee_ty = instance.ty(tcx, self.typing_env());
 
-        let ty::FnDef(def_id, fn_args) = *callee_ty.kind() else {
-            bug!("expected fn item type, found {}", callee_ty);
-        };
-
-        let name = tcx.item_name(def_id);
+        let name = tcx.item_name(instance.def_id());
+        let fn_args = instance.args;
 
         let simple = get_simple_intrinsic(self, name);
         let llval = match name {

compiler/rustc_codegen_ssa/src/mir/intrinsic.rs

@@ -1,7 +1,7 @@
 use rustc_abi::WrappingRange;
+use rustc_middle::bug;
 use rustc_middle::mir::SourceInfo;
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_middle::{bug, span_bug};
 use rustc_session::config::OptLevel;
 use rustc_span::sym;
 
@@ -60,14 +60,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         source_info: SourceInfo,
     ) -> Result<(), ty::Instance<'tcx>> {
         let span = source_info.span;
-        let callee_ty = instance.ty(bx.tcx(), bx.typing_env());
 
-        let ty::FnDef(def_id, fn_args) = *callee_ty.kind() else {
-            span_bug!(span, "expected fn item type, found {}", callee_ty);
-        };
-
-        let name = bx.tcx().item_name(def_id);
+        let name = bx.tcx().item_name(instance.def_id());
         let name_str = name.as_str();
+        let fn_args = instance.args;
 
         // If we're swapping something that's *not* an `OperandValue::Ref`,
         // then we can do it directly and avoid the alloca.
@@ -126,7 +122,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     sym::vtable_align => ty::COMMON_VTABLE_ENTRIES_ALIGN,
                     _ => bug!(),
                 };
-                let value = meth::VirtualIndex::from_index(idx).get_usize(bx, vtable, callee_ty);
+                let value = meth::VirtualIndex::from_index(idx).get_usize(
+                    bx,
+                    vtable,
+                    instance.ty(bx.tcx(), bx.typing_env()),
+                );
                 match name {
                     // Size is always <= isize::MAX.
                     sym::vtable_size => {