1 files changed, 40 insertions, 0 deletions
diff --git a/compiler/rustc_target/src/abi/call/x86_win64.rs b/compiler/rustc_target/src/abi/call/x86_win64.rs
new file mode 100644
index 000000000..2aad641b1
--- /dev/null
+++ b/compiler/rustc_target/src/abi/call/x86_win64.rs
@@ -0,0 +1,40 @@
+use crate::abi::call::{ArgAbi, FnAbi, Reg};
+use crate::abi::Abi;
+
+// Win64 ABI: https://docs.microsoft.com/en-us/cpp/build/parameter-passing
+
+pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
+    let fixup = |a: &mut ArgAbi<'_, Ty>| {
+        match a.layout.abi {
+            Abi::Uninhabited => {}
+            Abi::ScalarPair(..) | Abi::Aggregate { .. } => match a.layout.size.bits() {
+                8 => a.cast_to(Reg::i8()),
+                16 => a.cast_to(Reg::i16()),
+                32 => a.cast_to(Reg::i32()),
+                64 => a.cast_to(Reg::i64()),
+                _ => a.make_indirect(),
+            },
+            Abi::Vector { .. } => {
+                // FIXME(eddyb) there should be a size cap here
+                // (probably what clang calls "illegal vectors").
+            }
+            Abi::Scalar(_) => {
+                if a.layout.size.bytes() > 8 {
+                    a.make_indirect();
+                } else {
+                    a.extend_integer_width_to(32);
+                }
+            }
+        }
+    };
+
+    if !fn_abi.ret.is_ignore() {
+        fixup(&mut fn_abi.ret);
+    }
+    for arg in &mut fn_abi.args {
+        if arg.is_ignore() {
+            continue;
+        }
+        fixup(arg);
+    }
+}