fix: Check empty SIMD vector in inline asm

Author: eyraudh

compiler/rustc_hir_analysis/src/check/intrinsicck.rs

@@ -29,6 +29,7 @@ enum NonAsmTypeReason<'tcx> {
     Invalid(Ty<'tcx>),
     InvalidElement(DefId, Ty<'tcx>),
     NotSizedPtr(Ty<'tcx>),
+    EmptySIMDArray(Ty<'tcx>),
 }
 
 impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
@@ -102,6 +103,9 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
             }
             ty::Adt(adt, args) if adt.repr().simd() => {
                 let fields = &adt.non_enum_variant().fields;
+                if fields.is_empty() {
+                    return Err(NonAsmTypeReason::EmptySIMDArray(ty));
+                }
                 let field = &fields[FieldIdx::ZERO];
                 let elem_ty = field.ty(self.tcx(), args);
 
@@ -226,6 +230,10 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
                             can be used as arguments for inline assembly",
                         ).emit();
                     }
+                    NonAsmTypeReason::EmptySIMDArray(ty) => {
+                        let msg = format!("use of empty SIMD vector `{ty}`");
+                        self.infcx.dcx().struct_span_err(expr.span, msg).emit();
+                    }
                 }
                 return None;
             }

tests/crashes/134334.rs

@@ -0,0 +1,14 @@
+// Regression test for issue #134224.
+
+#![feature(repr_simd)]
+
+#[repr(simd)]
+struct A();
+//~^ ERROR SIMD vector cannot be empty
+
+fn main() {
+    unsafe {
+        std::arch::asm!("{}", in(xmm_reg) A());
+        //~^ use of empty SIMD vector `A`
+    }
+}

tests/ui/simd/empty-simd-vector-in-operand.rs

@@ -0,0 +1,15 @@
+error[E0075]: SIMD vector cannot be empty
+  --> $DIR/empty-simd-vector-in-operand.rs:6:1
+   |
+LL | struct A();
+   | ^^^^^^^^
+
+error: use of empty SIMD vector `A`
+  --> $DIR/empty-simd-vector-in-operand.rs:11:43
+   |
+LL |         std::arch::asm!("{}", in(xmm_reg) A());
+   |                                           ^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0075`.