u128 array zero fill - quick solution

Author: brody2consult

crates/rustc_codegen_spirv/src/builder/builder_methods.rs

@@ -308,6 +308,10 @@ fn memset_fill_u64(b: u8) -> u64 {
         | ((b as u64) << 56)
 }
 
+fn zero_fill_u128() -> u128 {
+    0 as u128
+}
+
 fn memset_dynamic_scalar(
     builder: &mut Builder<'_, '_>,
     fill_var: Word,
@@ -387,6 +391,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 64 => self
                     .constant_u64(self.span(), memset_fill_u64(fill_byte))
                     .def(self),
+                128 => {
+                    // NOTE: This is a quick solution to support the following case from issue #594:
+                    //     pub fn f() -> [u128; 2] { return [0; 2] }
+                    // This may be replaced by a more general memset fill solution in the future.
+                    if fill_byte != 0 {
+                        self.fatal("non-zero u128 array fill not implemented yet")
+                    }
+                    self.constant_u128(self.span(), zero_fill_u128()).def(self)
+                }
                 _ => self.fatal(format!(
                     "memset on integer width {width} not implemented yet"
                 )),

crates/rustc_codegen_spirv/src/codegen_cx/constant.rs

@@ -50,6 +50,10 @@ impl<'tcx> CodegenCx<'tcx> {
         self.constant_int_from_native_unsigned(span, val)
     }
 
+    pub fn constant_u128(&self, span: Span, val: u128) -> SpirvValue {
+        self.constant_int_from_native_unsigned(span, val)
+    }
+
     fn constant_int_from_native_unsigned(&self, span: Span, val: impl Into<u128>) -> SpirvValue {
         let size = Size::from_bytes(std::mem::size_of_val(&val));
         let ty = SpirvType::Integer(size.bits() as u32, false).def(span, self);

tests/compiletests/ui/memset_u128_array.rs

@@ -0,0 +1,8 @@
+// build-pass
+
+use spirv_std::spirv;
+
+pub fn f() -> [u128; 2] { return [0; 2] }
+
+#[spirv(fragment)]
+pub fn main() {}