Don't force many scalar pair values to the stack in write_cvalue_maybe_transmute

Sometimes it is necessary for handling vector to scalar pair transmutes,
but if the types are the same there is no need for this.

This improves runtime performance on simple-raytracer by 12%.

diff --git a/src/abi/comments.rs b/src/abi/comments.rs
index 7f4619b5c940b12f3701ca2aebba46e92808a163..abf63e33c35370ce39bbccb9d0c999217a0ce330 100644 (file)
--- a/src/abi/comments.rs
+++ b/src/abi/comments.rs
@@ -98,12 +98,12 @@ pub(super) fn add_local_place_comments<'tcx>(
         }
         CPlaceInner::VarPair(place_local, var1, var2) => {
             assert_eq!(local, place_local);
-            ("ssa", Cow::Owned(format!(",var=({}, {})", var1.index(), var2.index())))
+            ("ssa", Cow::Owned(format!("var=({}, {})", var1.index(), var2.index())))
         }
         CPlaceInner::VarLane(_local, _var, _lane) => unreachable!(),
         CPlaceInner::Addr(ptr, meta) => {
             let meta = if let Some(meta) = meta {
-                Cow::Owned(format!(",meta={}", meta))
+                Cow::Owned(format!("meta={}", meta))
             } else {
                 Cow::Borrowed("")
             };

diff --git a/src/value_and_place.rs b/src/value_and_place.rs
index fa06d6c3ba7f3a2a27b9f14b73d8862cfac75d87..cc4493d442f7ddfc1e46f502d070ef74822ba1f9 100644 (file)
--- a/src/value_and_place.rs
+++ b/src/value_and_place.rs
@@ -588,10 +588,13 @@ fn transmute_value<'tcx>(
                 return;
             }
             CPlaceInner::VarPair(_local, var1, var2) => {
-                let (ptr, meta) = from.force_stack(fx);
-                assert!(meta.is_none());
-                let (data1, data2) =
-                    CValue(CValueInner::ByRef(ptr, None), dst_layout).load_scalar_pair(fx);
+                let (data1, data2) = if self.layout().ty == dst_layout.ty {
+                    CValue(from.0, dst_layout).load_scalar_pair(fx)
+                } else {
+                    let (ptr, meta) = from.force_stack(fx);
+                    assert!(meta.is_none());
+                    CValue(CValueInner::ByRef(ptr, None), dst_layout).load_scalar_pair(fx)
+                };
                 let (dst_ty1, dst_ty2) = fx.clif_pair_type(self.layout().ty).unwrap();
                 transmute_value(fx, var1, data1, dst_ty1);
                 transmute_value(fx, var2, data2, dst_ty2);