Auto merge of #67414 - Mark-Simulacrum:rollup-gxjwn6c, r=Mark-Simulacrum

Rollup of 9 pull requests

Successful merges:

 - #67321 (make htons const fn)
 - #67328 (Remove now-redundant range check on u128 -> f32 casts)
 - #67333 ([mir-opt] Fix `Inline` pass to handle inlining into `box` expressions)
 - #67354 (Fix pointing at arg when cause is outside of call)
 - #67363 (Fix handling of wasm import modules and names)
 - #67382 (Remove some unnecessary `ATTR_*` constants.)
 - #67389 (Remove `SO_NOSIGPIPE` dummy variable on platforms that don't use it.)
 - #67393 (Enable opting out of specific default LLVM arguments.)
 - #67394 (Remove outdated references to @t from comments)

Failed merges:

r? @ghost

src/librustc/ich/mod.rs

@@ -12,21 +12,13 @@ mod impls_hir;
 mod impls_ty;
 mod impls_syntax;
 
-pub const ATTR_DIRTY: Symbol = sym::rustc_dirty;
-pub const ATTR_CLEAN: Symbol = sym::rustc_clean;
-pub const ATTR_IF_THIS_CHANGED: Symbol = sym::rustc_if_this_changed;
-pub const ATTR_THEN_THIS_WOULD_NEED: Symbol = sym::rustc_then_this_would_need;
-pub const ATTR_PARTITION_REUSED: Symbol = sym::rustc_partition_reused;
-pub const ATTR_PARTITION_CODEGENED: Symbol = sym::rustc_partition_codegened;
-pub const ATTR_EXPECTED_CGU_REUSE: Symbol = sym::rustc_expected_cgu_reuse;
-
 pub const IGNORED_ATTRIBUTES: &[Symbol] = &[
     sym::cfg,
-    ATTR_IF_THIS_CHANGED,
-    ATTR_THEN_THIS_WOULD_NEED,
-    ATTR_DIRTY,
-    ATTR_CLEAN,
-    ATTR_PARTITION_REUSED,
-    ATTR_PARTITION_CODEGENED,
-    ATTR_EXPECTED_CGU_REUSE,
+    sym::rustc_if_this_changed,
+    sym::rustc_then_this_would_need,
+    sym::rustc_dirty,
+    sym::rustc_clean,
+    sym::rustc_partition_reused,
+    sym::rustc_partition_codegened,
+    sym::rustc_expected_cgu_reuse,
 ];

src/librustc_codegen_llvm/attributes.rs

@@ -344,6 +344,17 @@ pub fn from_fn_attrs(
                 const_cstr!("wasm-import-module"),
                 &module,
             );
+
+            let name = codegen_fn_attrs.link_name.unwrap_or_else(|| {
+                cx.tcx.item_name(instance.def_id())
+            });
+            let name = CString::new(&name.as_str()[..]).unwrap();
+            llvm::AddFunctionAttrStringValue(
+                llfn,
+                llvm::AttributePlace::Function,
+                const_cstr!("wasm-import-name"),
+                &name,
+            );
         }
     }
 }

src/librustc_codegen_llvm/llvm_util.rs

@@ -3,6 +3,7 @@ use crate::llvm;
 use syntax_pos::symbol::Symbol;
 use rustc::session::Session;
 use rustc::session::config::PrintRequest;
+use rustc_data_structures::fx::FxHashSet;
 use rustc_target::spec::{MergeFunctions, PanicStrategy};
 use libc::c_int;
 use std::ffi::CString;
@@ -51,43 +52,60 @@ unsafe fn configure_llvm(sess: &Session) {
 
     llvm::LLVMRustInstallFatalErrorHandler();
 
+    fn llvm_arg_to_arg_name(full_arg: &str) -> &str {
+        full_arg.trim().split(|c: char| {
+            c == '=' || c.is_whitespace()
+        }).next().unwrap_or("")
+    }
+
+    let user_specified_args: FxHashSet<_> = sess
+        .opts
+        .cg
+        .llvm_args
+        .iter()
+        .map(|s| llvm_arg_to_arg_name(s))
+        .filter(|s| s.len() > 0)
+        .collect();
+
     {
-        let mut add = |arg: &str| {
-            let s = CString::new(arg).unwrap();
-            llvm_args.push(s.as_ptr());
-            llvm_c_strs.push(s);
+        // This adds the given argument to LLVM. Unless `force` is true
+        // user specified arguments are *not* overridden.
+        let mut add = |arg: &str, force: bool| {
+            if force || !user_specified_args.contains(llvm_arg_to_arg_name(arg)) {
+                let s = CString::new(arg).unwrap();
+                llvm_args.push(s.as_ptr());
+                llvm_c_strs.push(s);
+            }
         };
-        add("rustc"); // fake program name
-        if sess.time_llvm_passes() { add("-time-passes"); }
-        if sess.print_llvm_passes() { add("-debug-pass=Structure"); }
-        if sess.opts.debugging_opts.disable_instrumentation_preinliner {
-            add("-disable-preinline");
-        }
+        add("rustc", true); // fake program name
+        if sess.time_llvm_passes() { add("-time-passes", false); }
+        if sess.print_llvm_passes() { add("-debug-pass=Structure", false); }
+
         if sess.opts.debugging_opts.generate_arange_section {
-            add("-generate-arange-section");
+            add("-generate-arange-section", false);
         }
         if get_major_version() >= 8 {
             match sess.opts.debugging_opts.merge_functions
                   .unwrap_or(sess.target.target.options.merge_functions) {
                 MergeFunctions::Disabled |
                 MergeFunctions::Trampolines => {}
                 MergeFunctions::Aliases => {
-                    add("-mergefunc-use-aliases");
+                    add("-mergefunc-use-aliases", false);
                 }
             }
         }
 
         if sess.target.target.target_os == "emscripten" &&
             sess.panic_strategy() == PanicStrategy::Unwind {
-            add("-enable-emscripten-cxx-exceptions");
+            add("-enable-emscripten-cxx-exceptions", false);
         }
 
         // HACK(eddyb) LLVM inserts `llvm.assume` calls to preserve align attributes
         // during inlining. Unfortunately these may block other optimizations.
-        add("-preserve-alignment-assumptions-during-inlining=false");
+        add("-preserve-alignment-assumptions-during-inlining=false", false);
 
         for arg in &sess.opts.cg.llvm_args {
-            add(&(*arg));
+            add(&(*arg), true);
         }
     }
 

src/librustc_codegen_ssa/mir/rvalue.rs

@@ -341,6 +341,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                                     llval
                                 }
                             }
+                            (CastTy::Int(_), CastTy::Float) => {
+                                if signed {
+                                    bx.sitofp(llval, ll_t_out)
+                                } else {
+                                    bx.uitofp(llval, ll_t_out)
+                                }
+                            }
                             (CastTy::Ptr(_), CastTy::Ptr(_)) |
                             (CastTy::FnPtr, CastTy::Ptr(_)) |
                             (CastTy::RPtr(_), CastTy::Ptr(_)) =>
@@ -352,8 +359,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                                 let usize_llval = bx.intcast(llval, bx.cx().type_isize(), signed);
                                 bx.inttoptr(usize_llval, ll_t_out)
                             }
-                            (CastTy::Int(_), CastTy::Float) =>
-                                cast_int_to_float(&mut bx, signed, llval, ll_t_in, ll_t_out),
                             (CastTy::Float, CastTy::Int(IntTy::I)) =>
                                 cast_float_to_int(&mut bx, true, llval, ll_t_in, ll_t_out),
                             (CastTy::Float, CastTy::Int(_)) =>
@@ -720,40 +725,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
     }
 }
 
-fn cast_int_to_float<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
-    bx: &mut Bx,
-    signed: bool,
-    x: Bx::Value,
-    int_ty: Bx::Type,
-    float_ty: Bx::Type
-) -> Bx::Value {
-    // Most integer types, even i128, fit into [-f32::MAX, f32::MAX] after rounding.
-    // It's only u128 -> f32 that can cause overflows (i.e., should yield infinity).
-    // LLVM's uitofp produces undef in those cases, so we manually check for that case.
-    let is_u128_to_f32 = !signed &&
-        bx.cx().int_width(int_ty) == 128 &&
-        bx.cx().float_width(float_ty) == 32;
-    if is_u128_to_f32 {
-        // All inputs greater or equal to (f32::MAX + 0.5 ULP) are rounded to infinity,
-        // and for everything else LLVM's uitofp works just fine.
-        use rustc_apfloat::ieee::Single;
-        const MAX_F32_PLUS_HALF_ULP: u128 = ((1 << (Single::PRECISION + 1)) - 1)
-                                            << (Single::MAX_EXP - Single::PRECISION as i16);
-        let max = bx.cx().const_uint_big(int_ty, MAX_F32_PLUS_HALF_ULP);
-        let overflow = bx.icmp(IntPredicate::IntUGE, x, max);
-        let infinity_bits = bx.cx().const_u32(ieee::Single::INFINITY.to_bits() as u32);
-        let infinity = bx.bitcast(infinity_bits, float_ty);
-        let fp = bx.uitofp(x, float_ty);
-        bx.select(overflow, infinity, fp)
-    } else {
-        if signed {
-            bx.sitofp(x, float_ty)
-        } else {
-            bx.uitofp(x, float_ty)
-        }
-    }
-}
-
 fn cast_float_to_int<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     bx: &mut Bx,
     signed: bool,

src/librustc_codegen_utils/symbol_names.rs

@@ -142,12 +142,32 @@ fn symbol_name(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) -> Symbol {
     };
 
     let attrs = tcx.codegen_fn_attrs(def_id);
+
+    // Foreign items by default use no mangling for their symbol name. There's a
+    // few exceptions to this rule though:
+    //
+    // * This can be overridden with the `#[link_name]` attribute
+    //
+    // * On the wasm32 targets there is a bug (or feature) in LLD [1] where the
+    //   same-named symbol when imported from different wasm modules will get
+    //   hooked up incorectly. As a result foreign symbols, on the wasm target,
+    //   with a wasm import module, get mangled. Additionally our codegen will
+    //   deduplicate symbols based purely on the symbol name, but for wasm this
+    //   isn't quite right because the same-named symbol on wasm can come from
+    //   different modules. For these reasons if `#[link(wasm_import_module)]`
+    //   is present we mangle everything on wasm because the demangled form will
+    //   show up in the `wasm-import-name` custom attribute in LLVM IR.
+    //
+    // [1]: https://bugs.llvm.org/show_bug.cgi?id=44316
     if is_foreign {
-        if let Some(name) = attrs.link_name {
-            return name;
+        if tcx.sess.target.target.arch != "wasm32" ||
+            !tcx.wasm_import_module_map(def_id.krate).contains_key(&def_id)
+        {
+            if let Some(name) = attrs.link_name {
+                return name;
+            }
+            return tcx.item_name(def_id);
         }
-        // Don't mangle foreign items.
-        return tcx.item_name(def_id);
     }
 
     if let Some(name) = attrs.export_name {

src/librustc_incremental/assert_dep_graph.rs

@@ -44,11 +44,10 @@ use rustc_data_structures::graph::implementation::{
 };
 use rustc::hir;
 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
-use rustc::ich::{ATTR_IF_THIS_CHANGED, ATTR_THEN_THIS_WOULD_NEED};
 use std::env;
 use std::fs::{self, File};
 use std::io::Write;
-use syntax::ast;
+use syntax::{ast, symbol::sym};
 use syntax_pos::Span;
 
 pub fn assert_dep_graph(tcx: TyCtxt<'_>) {
@@ -78,7 +77,7 @@ pub fn assert_dep_graph(tcx: TyCtxt<'_>) {
             assert!(tcx.sess.opts.debugging_opts.query_dep_graph,
                     "cannot use the `#[{}]` or `#[{}]` annotations \
                     without supplying `-Z query-dep-graph`",
-                    ATTR_IF_THIS_CHANGED, ATTR_THEN_THIS_WOULD_NEED);
+                    sym::rustc_if_this_changed, sym::rustc_then_this_would_need);
         }
 
         // Check paths.
@@ -114,7 +113,7 @@ impl IfThisChanged<'tcx> {
         let def_id = self.tcx.hir().local_def_id(hir_id);
         let def_path_hash = self.tcx.def_path_hash(def_id);
         for attr in attrs {
-            if attr.check_name(ATTR_IF_THIS_CHANGED) {
+            if attr.check_name(sym::rustc_if_this_changed) {
                 let dep_node_interned = self.argument(attr);
                 let dep_node = match dep_node_interned {
                     None => def_path_hash.to_dep_node(DepKind::Hir),
@@ -130,7 +129,7 @@ impl IfThisChanged<'tcx> {
                     }
                 };
                 self.if_this_changed.push((attr.span, def_id, dep_node));
-            } else if attr.check_name(ATTR_THEN_THIS_WOULD_NEED) {
+            } else if attr.check_name(sym::rustc_then_this_would_need) {
                 let dep_node_interned = self.argument(attr);
                 let dep_node = match dep_node_interned {
                     Some(n) => {

src/librustc_incremental/assert_module_sources.rs

@@ -28,8 +28,6 @@ use rustc::ty::TyCtxt;
 use std::collections::BTreeSet;
 use syntax::ast;
 use syntax::symbol::{Symbol, sym};
-use rustc::ich::{ATTR_PARTITION_REUSED, ATTR_PARTITION_CODEGENED,
-                 ATTR_EXPECTED_CGU_REUSE};
 
 pub fn assert_module_sources(tcx: TyCtxt<'_>) {
     tcx.dep_graph.with_ignore(|| {
@@ -62,11 +60,11 @@ struct AssertModuleSource<'tcx> {
 
 impl AssertModuleSource<'tcx> {
     fn check_attr(&self, attr: &ast::Attribute) {
-        let (expected_reuse, comp_kind) = if attr.check_name(ATTR_PARTITION_REUSED) {
+        let (expected_reuse, comp_kind) = if attr.check_name(sym::rustc_partition_reused) {
             (CguReuse::PreLto, ComparisonKind::AtLeast)
-        } else if attr.check_name(ATTR_PARTITION_CODEGENED) {
+        } else if attr.check_name(sym::rustc_partition_codegened) {
             (CguReuse::No, ComparisonKind::Exact)
-        } else if attr.check_name(ATTR_EXPECTED_CGU_REUSE) {
+        } else if attr.check_name(sym::rustc_expected_cgu_reuse) {
             match &*self.field(attr, sym::kind).as_str() {
                 "no" => (CguReuse::No, ComparisonKind::Exact),
                 "pre-lto" => (CguReuse::PreLto, ComparisonKind::Exact),

src/librustc_incremental/persist/dirty_clean.rs

@@ -22,7 +22,6 @@ use rustc::hir::Node as HirNode;
 use rustc::hir::def_id::DefId;
 use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::hir::intravisit;
-use rustc::ich::{ATTR_DIRTY, ATTR_CLEAN};
 use rustc::ty::TyCtxt;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxHashSet;
@@ -224,7 +223,7 @@ pub fn check_dirty_clean_annotations(tcx: TyCtxt<'_>) {
 
         let mut all_attrs = FindAllAttrs {
             tcx,
-            attr_names: vec![ATTR_DIRTY, ATTR_CLEAN],
+            attr_names: vec![sym::rustc_dirty, sym::rustc_clean],
             found_attrs: vec![],
         };
         intravisit::walk_crate(&mut all_attrs, krate);
@@ -246,9 +245,9 @@ impl DirtyCleanVisitor<'tcx> {
     fn assertion_maybe(&mut self, item_id: hir::HirId, attr: &Attribute)
         -> Option<Assertion>
     {
-        let is_clean = if attr.check_name(ATTR_DIRTY) {
+        let is_clean = if attr.check_name(sym::rustc_dirty) {
             false
-        } else if attr.check_name(ATTR_CLEAN) {
+        } else if attr.check_name(sym::rustc_clean) {
             true
         } else {
             // skip: not rustc_clean/dirty

src/librustc_mir/transform/inline.rs

@@ -663,9 +663,9 @@ impl<'a, 'tcx> Integrator<'a, 'tcx> {
 
     fn make_integrate_local(&self, local: &Local) -> Local {
         if *local == RETURN_PLACE {
-            match self.destination.as_local() {
-                Some(l) => return l,
-                ref place => bug!("Return place is {:?}, not local", place),
+            match self.destination.base {
+                PlaceBase::Local(l) => return l,
+                PlaceBase::Static(ref s) => bug!("Return place is {:?}, not local", s),
             }
         }
 
@@ -695,14 +695,24 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
     fn visit_place(
         &mut self,
         place: &mut Place<'tcx>,
-        context: PlaceContext,
-        location: Location,
+        _context: PlaceContext,
+        _location: Location,
     ) {
-        if let Some(RETURN_PLACE) = place.as_local() {
-            // Return pointer; update the place itself
-            *place = self.destination.clone();
-        } else {
-            self.super_place(place, context, location);
+        match &mut place.base {
+            PlaceBase::Static(_) => {},
+            PlaceBase::Local(l) => {
+                // If this is the `RETURN_PLACE`, we need to rebase any projections onto it.
+                let dest_proj_len = self.destination.projection.len();
+                if *l == RETURN_PLACE && dest_proj_len > 0 {
+                    let mut projs = Vec::with_capacity(dest_proj_len + place.projection.len());
+                    projs.extend(self.destination.projection);
+                    projs.extend(place.projection);
+
+                    place.projection = self.tcx.intern_place_elems(&*projs);
+                }
+
+                *l = self.make_integrate_local(l);
+            }
         }
     }
 

src/librustc_session/config.rs

@@ -1488,8 +1488,6 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "extra arguments to prepend to the linker invocation (space separated)"),
     profile: bool = (false, parse_bool, [TRACKED],
                      "insert profiling code"),
-    disable_instrumentation_preinliner: bool = (false, parse_bool, [TRACKED],
-        "Disable the instrumentation pre-inliner, useful for profiling / PGO."),
     relro_level: Option<RelroLevel> = (None, parse_relro_level, [TRACKED],
         "choose which RELRO level to use"),
     nll_facts: bool = (false, parse_bool, [UNTRACKED],