From 318626710ee96b6ac2c59480bfc5f03048239220 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Fri, 18 Sep 2020 18:46:56 -0300
Subject: [PATCH] Do not make local copies of inline fns in debug mode

---
 compiler/rustc_middle/src/mir/mono.rs         | 19 +++++++------------
 .../inline-always-many-cgu/Makefile           |  7 ++++++-
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index 1e70f7605045..b79c1a19a907 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -1,7 +1,6 @@
 use crate::dep_graph::{DepConstructor, DepNode, WorkProduct, WorkProductId};
 use crate::ich::{NodeIdHashingMode, StableHashingContext};
 use crate::ty::{subst::InternalSubsts, Instance, InstanceDef, SymbolName, TyCtxt};
-use rustc_attr::InlineAttr;
 use rustc_data_structures::base_n;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxHashMap;
@@ -103,17 +102,13 @@ impl<'tcx> MonoItem<'tcx> {
                 // inlined function. If we're inlining into all CGUs then we'll
                 // be creating a local copy per CGU.
                 if generate_cgu_internal_copies {
-                    return InstantiationMode::LocalCopy;
-                }
-
-                // Finally, if this is `#[inline(always)]` we're sure to respect
-                // that with an inline copy per CGU, but otherwise we'll be
-                // creating one copy of this `#[inline]` function which may
-                // conflict with upstream crates as it could be an exported
-                // symbol.
-                match tcx.codegen_fn_attrs(instance.def_id()).inline {
-                    InlineAttr::Always => InstantiationMode::LocalCopy,
-                    _ => InstantiationMode::GloballyShared { may_conflict: true },
+                    InstantiationMode::LocalCopy
+                } else {
+                    // Finally, if we've reached this point, then we should optimize for
+                    // compilation speed. In that regard, we will ignore any `#[inline]`
+                    // annotations on the function and simply codegen it as usual. This could
+                    // conflict with upstream crates as it could be an exported symbol.
+                    InstantiationMode::GloballyShared { may_conflict: true }
                 }
             }
             MonoItem::Static(..) | MonoItem::GlobalAsm(..) => {
diff --git a/src/test/run-make-fulldeps/inline-always-many-cgu/Makefile b/src/test/run-make-fulldeps/inline-always-many-cgu/Makefile
index 0cab955f6442..d12a23fbbf01 100644
--- a/src/test/run-make-fulldeps/inline-always-many-cgu/Makefile
+++ b/src/test/run-make-fulldeps/inline-always-many-cgu/Makefile
@@ -1,7 +1,12 @@
 -include ../tools.mk
 
 all:
-	$(RUSTC) foo.rs --emit llvm-ir -C codegen-units=2
+	$(RUSTC) foo.rs --emit llvm-ir -C codegen-units=2 -C opt-level=0
+	if ![cat $(TMPDIR)/*.ll | $(CGREP) -e '\bcall\b']; then \
+		echo "not found call instruction when one was expected"; \
+		exit 1; \
+	fi
+	$(RUSTC) foo.rs --emit llvm-ir -C codegen-units=2 -C opt-level=1
 	if cat $(TMPDIR)/*.ll | $(CGREP) -e '\bcall\b'; then \
 		echo "found call instruction when one wasn't expected"; \
 		exit 1; \