mir: Don't memset allocas of types that do not require drop.

eddyb · eddyb · commit 02a141a5506a · 2016-03-17T22:48:07.000+02:00
diff --git a/src/librustc_trans/trans/mir/lvalue.rs b/src/librustc_trans/trans/mir/lvalue.rs
@@ -51,7 +51,9 @@ impl<'tcx> LvalueRef<'tcx> {
     {
         assert!(!ty.has_erasable_regions());
         let lltemp = bcx.with_block(|bcx| base::alloc_ty(bcx, ty, name));
-        drop::drop_fill(bcx, lltemp, ty);
+        if bcx.fcx().type_needs_drop(ty) {
+            drop::drop_fill(bcx, lltemp, ty);
+        }
         LvalueRef::new_sized(lltemp, LvalueTy::from_ty(ty))
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -51,7 +51,9 @@ impl<'tcx> LvalueRef<'tcx> {`
`51`	`51`	`{`
`52`	`52`	`assert!(!ty.has_erasable_regions());`
`53`	`53`	`let lltemp = bcx.with_block(\|bcx\| base::alloc_ty(bcx, ty, name));`
`54`		`- drop::drop_fill(bcx, lltemp, ty);`
	`54`	`+ if bcx.fcx().type_needs_drop(ty) {`
	`55`	`+ drop::drop_fill(bcx, lltemp, ty);`
	`56`	`+ }`
`55`	`57`	`LvalueRef::new_sized(lltemp, LvalueTy::from_ty(ty))`
`56`	`58`	`}`
`57`	`59`	`}`