7 files changed, 32 insertions, 49 deletions
diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index 5effe687528..4226ed7d99b 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -24,6 +24,7 @@ use tracing::{debug, info};
 use std::ffi::{CStr, CString};
 use std::fs::File;
 use std::io;
+use std::iter;
 use std::path::Path;
 use std::ptr;
 use std::slice;
@@ -916,9 +917,7 @@ impl ThinLTOKeysMap {
         modules: &[llvm::ThinLTOModule],
         names: &[CString],
     ) -> Self {
-        let keys = modules
-            .iter()
-            .zip(names.iter())
+        let keys = iter::zip(modules, names)
             .map(|(module, name)| {
                 let key = build_string(|rust_str| unsafe {
                     llvm::LLVMRustComputeLTOCacheKey(rust_str, module.identifier, data.0);
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 388dd7ce81b..085935b94df 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -548,6 +548,15 @@ pub(crate) unsafe fn optimize(
                     llvm::LLVMRustAddPass(fpm, find_pass("lint").unwrap());
                     continue;
                 }
+                if pass_name == "insert-gcov-profiling" || pass_name == "instrprof" {
+                    // Instrumentation must be inserted before optimization,
+                    // otherwise LLVM may optimize some functions away which
+                    // breaks llvm-cov.
+                    //
+                    // This mirrors what Clang does in lib/CodeGen/BackendUtil.cpp.
+                    llvm::LLVMRustAddPass(mpm, find_pass(pass_name).unwrap());
+                    continue;
+                }
 
                 if let Some(pass) = find_pass(pass_name) {
                     extra_passes.push(pass);
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index f4852c91e53..896e56a9a1e 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -21,6 +21,7 @@ use rustc_target::abi::{self, Align, Size};
 use rustc_target::spec::{HasTargetSpec, Target};
 use std::borrow::Cow;
 use std::ffi::CStr;
+use std::iter;
 use std::ops::{Deref, Range};
 use std::ptr;
 use tracing::debug;
@@ -1352,18 +1353,14 @@ impl Builder<'a, 'll, 'tcx> {
 
         let param_tys = self.cx.func_params_types(fn_ty);
 
-        let all_args_match = param_tys
-            .iter()
-            .zip(args.iter().map(|&v| self.val_ty(v)))
+        let all_args_match = iter::zip(&param_tys, args.iter().map(|&v| self.val_ty(v)))
             .all(|(expected_ty, actual_ty)| *expected_ty == actual_ty);
 
         if all_args_match {
             return Cow::Borrowed(args);
         }
 
-        let casted_args: Vec<_> = param_tys
-            .into_iter()
-            .zip(args.iter())
+        let casted_args: Vec<_> = iter::zip(param_tys, args)
             .enumerate()
             .map(|(i, (expected_ty, &actual_val))| {
                 let actual_ty = self.val_ty(actual_val);
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
index d5b32e58cc3..d90e93f116c 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
@@ -1962,9 +1962,7 @@ fn prepare_enum_metadata(
 
     let discriminant_type_metadata = |discr: Primitive| {
         let enumerators_metadata: Vec<_> = match enum_type.kind() {
-            ty::Adt(def, _) => def
-                .discriminants(tcx)
-                .zip(&def.variants)
+            ty::Adt(def, _) => iter::zip(def.discriminants(tcx), &def.variants)
                 .map(|((_, discr), v)| {
                     let name = v.ident.as_str();
                     let is_unsigned = match discr.ty.kind() {
@@ -2336,9 +2334,7 @@ fn compute_type_parameters(cx: &CodegenCx<'ll, 'tcx>, ty: Ty<'tcx>) -> &'ll DIAr
         if substs.types().next().is_some() {
             let generics = cx.tcx.generics_of(def.did);
             let names = get_parameter_names(cx, generics);
-            let template_params: Vec<_> = substs
-                .iter()
-                .zip(names)
+            let template_params: Vec<_> = iter::zip(substs, names)
                 .filter_map(|(kind, name)| {
                     if let GenericArgKind::Type(ty) = kind.unpack() {
                         let actual_type =
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
index abb87cb3656..e157a38aa03 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
@@ -37,6 +37,7 @@ use rustc_target::abi::{LayoutOf, Primitive, Size};
 use libc::c_uint;
 use smallvec::SmallVec;
 use std::cell::RefCell;
+use std::iter;
 use tracing::debug;
 
 mod create_scope_map;
@@ -448,9 +449,7 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
             // Again, only create type information if full debuginfo is enabled
             let template_params: Vec<_> = if cx.sess().opts.debuginfo == DebugInfo::Full {
                 let names = get_parameter_names(cx, generics);
-                substs
-                    .iter()
-                    .zip(names)
+                iter::zip(substs, names)
                     .filter_map(|(kind, name)| {
                         if let GenericArgKind::Type(ty) = kind.unpack() {
                             let actual_type =
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index de7f5fc6e29..5ca4b226c38 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -11,6 +11,7 @@
 #![feature(extended_key_value_attributes)]
 #![feature(extern_types)]
 #![feature(in_band_lifetimes)]
+#![feature(iter_zip)]
 #![feature(nll)]
 #![cfg_attr(bootstrap, feature(or_patterns))]
 #![recursion_limit = "256"]
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 82cd1be3b3b..af9d3d2dc26 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -190,33 +190,6 @@ pub enum RealPredicate {
     RealPredicateTrue = 15,
 }
 
-impl RealPredicate {
-    pub fn from_generic(realpred: rustc_codegen_ssa::common::RealPredicate) -> Self {
-        match realpred {
-            rustc_codegen_ssa::common::RealPredicate::RealPredicateFalse => {
-                RealPredicate::RealPredicateFalse
-            }
-            rustc_codegen_ssa::common::RealPredicate::RealOEQ => RealPredicate::RealOEQ,
-            rustc_codegen_ssa::common::RealPredicate::RealOGT => RealPredicate::RealOGT,
-            rustc_codegen_ssa::common::RealPredicate::RealOGE => RealPredicate::RealOGE,
-            rustc_codegen_ssa::common::RealPredicate::RealOLT => RealPredicate::RealOLT,
-            rustc_codegen_ssa::common::RealPredicate::RealOLE => RealPredicate::RealOLE,
-            rustc_codegen_ssa::common::RealPredicate::RealONE => RealPredicate::RealONE,
-            rustc_codegen_ssa::common::RealPredicate::RealORD => RealPredicate::RealORD,
-            rustc_codegen_ssa::common::RealPredicate::RealUNO => RealPredicate::RealUNO,
-            rustc_codegen_ssa::common::RealPredicate::RealUEQ => RealPredicate::RealUEQ,
-            rustc_codegen_ssa::common::RealPredicate::RealUGT => RealPredicate::RealUGT,
-            rustc_codegen_ssa::common::RealPredicate::RealUGE => RealPredicate::RealUGE,
-            rustc_codegen_ssa::common::RealPredicate::RealULT => RealPredicate::RealULT,
-            rustc_codegen_ssa::common::RealPredicate::RealULE => RealPredicate::RealULE,
-            rustc_codegen_ssa::common::RealPredicate::RealUNE => RealPredicate::RealUNE,
-            rustc_codegen_ssa::common::RealPredicate::RealPredicateTrue => {
-                RealPredicate::RealPredicateTrue
-            }
-        }
-    }
-}
-
 /// LLVMTypeKind
 #[derive(Copy, Clone, PartialEq, Debug)]
 #[repr(C)]
@@ -711,7 +684,7 @@ pub mod coverageinfo {
     }
 
     impl CounterMappingRegion {
-        pub fn code_region(
+        crate fn code_region(
             counter: coverage_map::Counter,
             file_id: u32,
             start_line: u32,
@@ -731,7 +704,10 @@ pub mod coverageinfo {
             }
         }
 
-        pub fn expansion_region(
+        // This function might be used in the future; the LLVM API is still evolving, as is coverage
+        // support.
+        #[allow(dead_code)]
+        crate fn expansion_region(
             file_id: u32,
             expanded_file_id: u32,
             start_line: u32,
@@ -751,7 +727,10 @@ pub mod coverageinfo {
             }
         }
 
-        pub fn skipped_region(
+        // This function might be used in the future; the LLVM API is still evolving, as is coverage
+        // support.
+        #[allow(dead_code)]
+        crate fn skipped_region(
             file_id: u32,
             start_line: u32,
             start_col: u32,
@@ -770,7 +749,10 @@ pub mod coverageinfo {
             }
         }
 
-        pub fn gap_region(
+        // This function might be used in the future; the LLVM API is still evolving, as is coverage
+        // support.
+        #[allow(dead_code)]
+        crate fn gap_region(
             counter: coverage_map::Counter,
             file_id: u32,
             start_line: u32,