Auto merge of #2183 - RalfJung:better-provenance-control, r=RalfJung

[rust.git] / src / shims / foreign_items.rs

diff --git a/src/shims/foreign_items.rs b/src/shims/foreign_items.rs
index ba4e384846be40324f0e74e98ea9f43350386e6b..12b5b40e69e88b38c86e15d04b8e226238363a59 100644 (file)
--- a/src/shims/foreign_items.rs
+++ b/src/shims/foreign_items.rs
@@ -15,13 +15,14 @@
 use rustc_middle::mir;
 use rustc_middle::ty;
 use rustc_session::config::CrateType;
-use rustc_span::{symbol::sym, Symbol};
+use rustc_span::Symbol;
 use rustc_target::{
     abi::{Align, Size},
     spec::abi::Abi,
 };
 
 use super::backtrace::EvalContextExt as _;
+use crate::helpers::convert::Truncate;
 use crate::*;
 
 /// Returned by `emulate_foreign_item_by_name`.
@@ -41,7 +42,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     /// Returns the minimum alignment for the target architecture for allocations of the given size.
     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
         let this = self.eval_context_ref();
-        // List taken from `libstd/sys_common/alloc.rs`.
+        // List taken from `library/std/src/sys/common/alloc.rs`.
+        // This list should be kept in sync with the one from libstd.
         let min_align = match this.tcx.sess.target.arch.as_ref() {
             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
@@ -230,20 +232,16 @@ fn emulate_foreign_item(
         def_id: DefId,
         abi: Abi,
         args: &[OpTy<'tcx, Tag>],
-        ret: Option<(&PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
+        dest: &PlaceTy<'tcx, Tag>,
+        ret: Option<mir::BasicBlock>,
         unwind: StackPopUnwind,
     ) -> InterpResult<'tcx, Option<(&'mir mir::Body<'tcx>, ty::Instance<'tcx>)>> {
         let this = self.eval_context_mut();
-        let attrs = this.tcx.get_attrs(def_id);
-        let link_name = this
-            .tcx
-            .sess
-            .first_attr_value_str_by_name(attrs, sym::link_name)
-            .unwrap_or_else(|| this.tcx.item_name(def_id));
+        let link_name = this.item_link_name(def_id);
         let tcx = this.tcx.tcx;
 
         // First: functions that diverge.
-        let (dest, ret) = match ret {
+        let ret = match ret {
             None =>
                 match &*link_name.as_str() {
                     "miri_start_panic" => {
@@ -677,8 +675,8 @@ fn emulate_foreign_item_by_name(
                 let a = this.read_scalar(a)?.to_u64()?;
                 let b = this.read_scalar(b)?.to_u64()?;
 
-                let wide_sum = c_in as u128 + a as u128 + b as u128;
-                let (c_out, sum) = ((wide_sum >> 64) as u8, wide_sum as u64);
+                let wide_sum = u128::from(c_in) + u128::from(a) + u128::from(b);
+                let (c_out, sum) = ((wide_sum >> 64).truncate::<u8>(), wide_sum.truncate::<u64>());
 
                 let c_out_field = this.place_field(dest, 0)?;
                 this.write_scalar(Scalar::from_u8(c_out), &c_out_field)?;
@@ -704,7 +702,7 @@ fn emulate_foreign_item_by_name(
 
             // Platform-specific shims
             _ => match this.tcx.sess.target.os.as_ref() {
-                "linux" | "macos" => return shims::posix::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, abi, args, dest, ret),
+                "linux" | "macos" => return shims::unix::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, abi, args, dest, ret),
                 "windows" => return shims::windows::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, abi, args, dest, ret),
                 target => throw_unsup_format!("the target `{}` is not supported", target),
             }