Auto merge of #124932 - RalfJung:temporal, r=compiler-errors

codegen: memmove/memset cannot be non-temporal

non-temporal memset is not a thing.
And for memmove, since the LLVM backend doesn't support this, surely we don't need it in the GCC backend.

compiler/rustc_codegen_gcc/src/builder.rs

@@ -1301,19 +1301,13 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
     fn memmove(
         &mut self,
         dst: RValue<'gcc>,
-        dst_align: Align,
+        _dst_align: Align,
         src: RValue<'gcc>,
-        src_align: Align,
+        _src_align: Align,
         size: RValue<'gcc>,
         flags: MemFlags,
     ) {
-        if flags.contains(MemFlags::NONTEMPORAL) {
-            // HACK(nox): This is inefficient but there is no nontemporal memmove.
-            let val = self.load(src.get_type().get_pointee().expect("get_pointee"), src, src_align);
-            let ptr = self.pointercast(dst, self.type_ptr_to(self.val_ty(val)));
-            self.store_with_flags(val, ptr, dst_align, flags);
-            return;
-        }
+        assert!(!flags.contains(MemFlags::NONTEMPORAL), "non-temporal memmove not supported");
         let size = self.intcast(size, self.type_size_t(), false);
         let _is_volatile = flags.contains(MemFlags::VOLATILE);
         let dst = self.pointercast(dst, self.type_i8p());
@@ -1335,6 +1329,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         _align: Align,
         flags: MemFlags,
     ) {
+        assert!(!flags.contains(MemFlags::NONTEMPORAL), "non-temporal memset not supported");
         let _is_volatile = flags.contains(MemFlags::VOLATILE);
         let ptr = self.pointercast(ptr, self.type_i8p());
         let memset = self.context.get_builtin_function("memset");

compiler/rustc_codegen_llvm/src/builder.rs

@@ -976,6 +976,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         align: Align,
         flags: MemFlags,
     ) {
+        assert!(!flags.contains(MemFlags::NONTEMPORAL), "non-temporal memset not supported");
         let is_volatile = flags.contains(MemFlags::VOLATILE);
         unsafe {
             llvm::LLVMRustBuildMemSet(