librustc: implement and use fixed_stack_segment attribute for intrinsics.

Author: huonw

src/libcore/unstable/intrinsics.rs

@@ -70,16 +70,28 @@ pub extern "rust-intrinsic" {
     pub fn powif32(a: f32, x: i32) -> f32;
     pub fn powif64(a: f64, x: i32) -> f64;
 
+    // the following kill the stack canary without
+    // `fixed_stack_segment`. This possibly only affects the f64
+    // variants, but it's hard to be sure since it seems to only
+    // occur with fairly specific arguments.
+    #[fixed_stack_segment]
     pub fn sinf32(x: f32) -> f32;
+    #[fixed_stack_segment]
     pub fn sinf64(x: f64) -> f64;
 
+    #[fixed_stack_segment]
     pub fn cosf32(x: f32) -> f32;
+    #[fixed_stack_segment]
     pub fn cosf64(x: f64) -> f64;
 
+    #[fixed_stack_segment]
     pub fn powf32(a: f32, x: f32) -> f32;
+    #[fixed_stack_segment]
     pub fn powf64(a: f64, x: f64) -> f64;
 
+    #[fixed_stack_segment]
     pub fn expf32(x: f32) -> f32;
+    #[fixed_stack_segment]
     pub fn expf64(x: f64) -> f64;
 
     pub fn exp2f32(x: f32) -> f32;
@@ -128,4 +140,3 @@ pub extern "rust-intrinsic" {
     pub fn bswap32(x: i32) -> i32;
     pub fn bswap64(x: i64) -> i64;
 }
-

src/librustc/middle/trans/foreign.rs

@@ -546,6 +546,7 @@ pub fn trans_intrinsic(ccx: @CrateContext,
                        item: @ast::foreign_item,
                        path: ast_map::path,
                        substs: @param_substs,
+                       attributes: &[ast::attribute],
                        ref_id: Option<ast::node_id>) {
     debug!("trans_intrinsic(item.ident=%s)", *ccx.sess.str_of(item.ident));
 
@@ -561,6 +562,11 @@ pub fn trans_intrinsic(ccx: @CrateContext,
                                Some(copy substs),
                                Some(item.span));
 
+    // Set the fixed stack segment flag if necessary.
+    if attr::attrs_contains_name(attributes, "fixed_stack_segment") {
+        set_fixed_stack_segment(fcx.llfn);
+    }
+
     let mut bcx = top_scope_block(fcx, None), lltop = bcx.llbb;
     match *ccx.sess.str_of(item.ident) {
         ~"atomic_cxchg" => {

src/librustc/middle/trans/monomorphize.rs

@@ -212,7 +212,7 @@ pub fn monomorphic_fn(ccx: @CrateContext,
       }
       ast_map::node_foreign_item(i, _, _, _) => {
           let d = mk_lldecl();
-          foreign::trans_intrinsic(ccx, d, i, pt, psubsts.get(),
+          foreign::trans_intrinsic(ccx, d, i, pt, psubsts.get(), i.attrs,
                                 ref_id);
           d
       }