From 4c2d4cd3dea344e81e4df24382ac3f23e2f86f40 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= Date: Fri, 25 Jul 2014 07:29:12 +0200 Subject: [PATCH] Add noalias to safe shared reference parameters This add the LLVM noalias attribute to parameters of a shared reference type (&) which have a safe interior. --- src/librustc/middle/trans/base.rs | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs index 68d8ab3f04c6f..fcdcb7847cb76 100644 --- a/src/librustc/middle/trans/base.rs +++ b/src/librustc/middle/trans/base.rs @@ -2140,7 +2140,10 @@ pub fn get_fn_llvm_attributes(ccx: &CrateContext, fn_ty: ty::t) attrs.push((idx, llvm::NonNullAttribute as u64)); } // `&mut` pointer parameters never alias other parameters, or mutable global data - ty::ty_rptr(b, mt) if mt.mutbl == ast::MutMutable => { + // `&` pointer parameters never alias either (for LLVM's purposes) as long as the + // interior is safe + ty::ty_rptr(b, mt) if mt.mutbl == ast::MutMutable || + !ty::type_contents(ccx.tcx(), mt.ty).interior_unsafe() => { attrs.push((idx, llvm::NoAliasAttribute as u64)); attrs.push((idx, llvm::NonNullAttribute as u64)); match b {