From cc08749df2613c17c8c2e9d8224a24a24c126423 Mon Sep 17 00:00:00 2001
From: DianQK <dianqk@dianqk.net>
Date: Tue, 18 Jul 2023 22:15:47 +0800
Subject: [PATCH] Add the `no-builtins` attribute to functions when
`no_builtins` is applied at the crate level.
When `no_builtins` is applied at the crate level, we should add the
`no-builtins` attribute to each function to ensure it takes effect in LTO.
---
compiler/rustc_codegen_llvm/src/attributes.rs | 4 ++++
.../rustc_codegen_ssa/src/codegen_attrs.rs | 10 +++++++-
.../src/middle/codegen_fn_attrs.rs | 2 ++
tests/codegen/no_builtins-at-crate.rs | 24 +++++++++++++++++++
tests/run-make/no-builtins-attribute/Makefile | 9 +++++++
.../no-builtins-attribute/filecheck.main.txt | 5 ++++
tests/run-make/no-builtins-attribute/main.rs | 10 ++++++++
.../no-builtins-attribute/no_builtins.rs | 5 ++++
8 files changed, 68 insertions(+), 1 deletion(-)
create mode 100644 tests/codegen/no_builtins-at-crate.rs
create mode 100644 tests/run-make/no-builtins-attribute/Makefile
create mode 100644 tests/run-make/no-builtins-attribute/filecheck.main.txt
create mode 100644 tests/run-make/no-builtins-attribute/main.rs
create mode 100644 tests/run-make/no-builtins-attribute/no_builtins.rs
diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index 39275272e4226..4c69b9503a2cf 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -335,6 +335,10 @@ pub fn from_fn_attrs<'ll, 'tcx>(
to_add.extend(probestack_attr(cx));
to_add.extend(stackprotector_attr(cx));
+ if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_BUILTINS) {
+ to_add.push(llvm::CreateAttrString(cx.llcx, "no-builtins"));
+ }
+
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
to_add.push(AttributeKind::Cold.create_attr(cx.llcx));
}
diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
index d6c2301276262..0c7b8a7961281 100644
--- a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
+++ b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -1,4 +1,4 @@
-use rustc_ast::{ast, MetaItemKind, NestedMetaItem};
+use rustc_ast::{ast, attr, MetaItemKind, NestedMetaItem};
use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
use rustc_errors::struct_span_err;
use rustc_hir as hir;
@@ -60,6 +60,14 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
}
+ // When `no_builtins` is applied at the crate level, we should add the
+ // `no-builtins` attribute to each function to ensure it takes effect in LTO.
+ let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID);
+ let no_builtins = attr::contains_name(crate_attrs, sym::no_builtins);
+ if no_builtins {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_BUILTINS;
+ }
+
let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
let mut inline_span = None;
diff --git a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
index c4601a1fb4189..02fd6ed7ba6ba 100644
--- a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
+++ b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
@@ -100,6 +100,8 @@ bitflags! {
const REALLOCATOR = 1 << 18;
/// `#[rustc_allocator_zeroed]`: a hint to LLVM that the function only allocates zeroed memory.
const ALLOCATOR_ZEROED = 1 << 19;
+ /// `#[no_builtins]`: indicates that disable implicit builtin knowledge of functions for the function.
+ const NO_BUILTINS = 1 << 20;
}
}
diff --git a/tests/codegen/no_builtins-at-crate.rs b/tests/codegen/no_builtins-at-crate.rs
new file mode 100644
index 0000000000000..02ed670900ed7
--- /dev/null
+++ b/tests/codegen/no_builtins-at-crate.rs
@@ -0,0 +1,24 @@
+// compile-flags: -C opt-level=1
+
+#![no_builtins]
+#![crate_type = "lib"]
+
+// CHECK: define
+// CHECK-SAME: @__aeabi_memcpy
+// CHECK-SAME: #0
+#[no_mangle]
+pub unsafe extern "C" fn __aeabi_memcpy(dest: *mut u8, src: *const u8, size: usize) {
+ // CHECK: call
+ // CHECK-SAME: @memcpy(
+ memcpy(dest, src, size);
+}
+
+// CHECK: declare
+// CHECK-SAME: @memcpy
+// CHECK-SAME: #0
+extern "C" {
+ pub fn memcpy(dest: *mut u8, src: *const u8, n: usize) -> *mut u8;
+}
+
+// CHECK: attributes #0
+// CHECK-SAME: "no-builtins"
diff --git a/tests/run-make/no-builtins-attribute/Makefile b/tests/run-make/no-builtins-attribute/Makefile
new file mode 100644
index 0000000000000..0ce95facaea48
--- /dev/null
+++ b/tests/run-make/no-builtins-attribute/Makefile
@@ -0,0 +1,9 @@
+include ../tools.mk
+
+# We want to check if `no-builtins` is also added to the function declarations in the used crate.
+
+all:
+ $(RUSTC) no_builtins.rs --emit=link
+ $(RUSTC) main.rs --emit=llvm-ir
+
+ cat "$(TMPDIR)"/main.ll | "$(LLVM_FILECHECK)" filecheck.main.txt
diff --git a/tests/run-make/no-builtins-attribute/filecheck.main.txt b/tests/run-make/no-builtins-attribute/filecheck.main.txt
new file mode 100644
index 0000000000000..ecd650bdca804
--- /dev/null
+++ b/tests/run-make/no-builtins-attribute/filecheck.main.txt
@@ -0,0 +1,5 @@
+CHECK: declare void @foo()
+CHECK-SAME: #[[ATTR_3:[0-9]+]]
+
+CHECK: attributes #[[ATTR_3]]
+CHECK-SAME: no-builtins
diff --git a/tests/run-make/no-builtins-attribute/main.rs b/tests/run-make/no-builtins-attribute/main.rs
new file mode 100644
index 0000000000000..77754b37e3184
--- /dev/null
+++ b/tests/run-make/no-builtins-attribute/main.rs
@@ -0,0 +1,10 @@
+extern crate no_builtins;
+
+#[no_mangle]
+fn call_foo() {
+ no_builtins::foo();
+}
+
+fn main() {
+ call_foo();
+}
diff --git a/tests/run-make/no-builtins-attribute/no_builtins.rs b/tests/run-make/no-builtins-attribute/no_builtins.rs
new file mode 100644
index 0000000000000..8ca862d2f7773
--- /dev/null
+++ b/tests/run-make/no-builtins-attribute/no_builtins.rs
@@ -0,0 +1,5 @@
+#![crate_type = "lib"]
+#![no_builtins]
+
+#[no_mangle]
+pub fn foo() {}