From db24d8e8e25192703eb8f2ad6864207e92979443 Mon Sep 17 00:00:00 2001
From: Nikita Popov <nikita.ppv@gmail.com>
Date: Fri, 21 Dec 2018 00:30:35 +0100
Subject: [PATCH] Enable emission of alignment attrs for pointer params
Instead disable creation of assumptions during inlining using an
LLVM opt flag.
The -Z arg-align-attributes option which previously controlled this
behavior is removed.
---
src/librustc/session/config.rs | 2 --
src/librustc_codegen_llvm/abi.rs | 6 -----
src/librustc_codegen_llvm/llvm_util.rs | 4 ++++
src/test/codegen/function-arguments.rs | 32 +++++++++++++-------------
4 files changed, 20 insertions(+), 24 deletions(-)
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index b58d80e24857d..8bb3fc1295205 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1271,8 +1271,6 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
"set the MIR optimization level (0-3, default: 1)"),
mutable_noalias: Option<bool> = (None, parse_opt_bool, [TRACKED],
"emit noalias metadata for mutable references (default: yes on LLVM >= 6)"),
- arg_align_attributes: bool = (false, parse_bool, [TRACKED],
- "emit align metadata for reference arguments"),
dump_mir: Option<String> = (None, parse_opt_string, [UNTRACKED],
"dump MIR state to file.
`val` is used to select which passes and functions to dump. For example:
diff --git a/src/librustc_codegen_llvm/abi.rs b/src/librustc_codegen_llvm/abi.rs
index b8954dee794f7..71b75525a5aa1 100644
--- a/src/librustc_codegen_llvm/abi.rs
+++ b/src/librustc_codegen_llvm/abi.rs
@@ -489,12 +489,6 @@ impl<'tcx> FnTypeExt<'tcx> for FnType<'tcx, Ty<'tcx>> {
attrs.pointee_size = pointee.size;
attrs.pointee_align = Some(pointee.align);
- // HACK(eddyb) LLVM inserts `llvm.assume` calls when inlining functions
- // with align attributes, and those calls later block optimizations.
- if !is_return && !cx.tcx.sess.opts.debugging_opts.arg_align_attributes {
- attrs.pointee_align = None;
- }
-
// `Box` pointer parameters never alias because ownership is transferred
// `&mut` pointer parameters never alias other parameters,
// or mutable global data
diff --git a/src/librustc_codegen_llvm/llvm_util.rs b/src/librustc_codegen_llvm/llvm_util.rs
index 82b1d7e8b40e4..090ff83ecc1a8 100644
--- a/src/librustc_codegen_llvm/llvm_util.rs
+++ b/src/librustc_codegen_llvm/llvm_util.rs
@@ -74,6 +74,10 @@ unsafe fn configure_llvm(sess: &Session) {
add("-mergefunc-use-aliases");
}
+ // 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");
+
for arg in &sess.opts.cg.llvm_args {
add(&(*arg));
}
diff --git a/src/test/codegen/function-arguments.rs b/src/test/codegen/function-arguments.rs
index 52bdb1b103afd..69632c9c82b70 100644
--- a/src/test/codegen/function-arguments.rs
+++ b/src/test/codegen/function-arguments.rs
@@ -28,37 +28,37 @@ pub fn boolean(x: bool) -> bool {
x
}
-// CHECK: @readonly_borrow(i32* noalias readonly dereferenceable(4) %arg0)
+// CHECK: @readonly_borrow(i32* noalias readonly align 4 dereferenceable(4) %arg0)
// FIXME #25759 This should also have `nocapture`
#[no_mangle]
pub fn readonly_borrow(_: &i32) {
}
-// CHECK: @static_borrow(i32* noalias readonly dereferenceable(4) %arg0)
+// CHECK: @static_borrow(i32* noalias readonly align 4 dereferenceable(4) %arg0)
// static borrow may be captured
#[no_mangle]
pub fn static_borrow(_: &'static i32) {
}
-// CHECK: @named_borrow(i32* noalias readonly dereferenceable(4) %arg0)
+// CHECK: @named_borrow(i32* noalias readonly align 4 dereferenceable(4) %arg0)
// borrow with named lifetime may be captured
#[no_mangle]
pub fn named_borrow<'r>(_: &'r i32) {
}
-// CHECK: @unsafe_borrow(i16* dereferenceable(2) %arg0)
+// CHECK: @unsafe_borrow(i16* align 2 dereferenceable(2) %arg0)
// unsafe interior means this isn't actually readonly and there may be aliases ...
#[no_mangle]
pub fn unsafe_borrow(_: &UnsafeInner) {
}
-// CHECK: @mutable_unsafe_borrow(i16* dereferenceable(2) %arg0)
+// CHECK: @mutable_unsafe_borrow(i16* align 2 dereferenceable(2) %arg0)
// ... unless this is a mutable borrow, those never alias
#[no_mangle]
pub fn mutable_unsafe_borrow(_: &mut UnsafeInner) {
}
-// CHECK: @mutable_borrow(i32* dereferenceable(4) %arg0)
+// CHECK: @mutable_borrow(i32* align 4 dereferenceable(4) %arg0)
// FIXME #25759 This should also have `nocapture`
#[no_mangle]
pub fn mutable_borrow(_: &mut i32) {
@@ -69,13 +69,13 @@ pub fn mutable_borrow(_: &mut i32) {
pub fn indirect_struct(_: S) {
}
-// CHECK: @borrowed_struct(%S* noalias readonly dereferenceable(32) %arg0)
+// CHECK: @borrowed_struct(%S* noalias readonly align 4 dereferenceable(32) %arg0)
// FIXME #25759 This should also have `nocapture`
#[no_mangle]
pub fn borrowed_struct(_: &S) {
}
-// CHECK: noalias align 4 dereferenceable(4) i32* @_box(i32* noalias dereferenceable(4) %x)
+// CHECK: noalias align 4 dereferenceable(4) i32* @_box(i32* noalias align 4 dereferenceable(4) %x)
#[no_mangle]
pub fn _box(x: Box<i32>) -> Box<i32> {
x
@@ -95,48 +95,48 @@ pub fn struct_return() -> S {
pub fn helper(_: usize) {
}
-// CHECK: @slice([0 x i8]* noalias nonnull readonly %arg0.0, [[USIZE]] %arg0.1)
+// CHECK: @slice([0 x i8]* noalias nonnull readonly align 1 %arg0.0, [[USIZE]] %arg0.1)
// FIXME #25759 This should also have `nocapture`
#[no_mangle]
pub fn slice(_: &[u8]) {
}
-// CHECK: @mutable_slice([0 x i8]* nonnull %arg0.0, [[USIZE]] %arg0.1)
+// CHECK: @mutable_slice([0 x i8]* nonnull align 1 %arg0.0, [[USIZE]] %arg0.1)
// FIXME #25759 This should also have `nocapture`
#[no_mangle]
pub fn mutable_slice(_: &mut [u8]) {
}
-// CHECK: @unsafe_slice([0 x i16]* nonnull %arg0.0, [[USIZE]] %arg0.1)
+// CHECK: @unsafe_slice([0 x i16]* nonnull align 2 %arg0.0, [[USIZE]] %arg0.1)
// unsafe interior means this isn't actually readonly and there may be aliases ...
#[no_mangle]
pub fn unsafe_slice(_: &[UnsafeInner]) {
}
-// CHECK: @str([0 x i8]* noalias nonnull readonly %arg0.0, [[USIZE]] %arg0.1)
+// CHECK: @str([0 x i8]* noalias nonnull readonly align 1 %arg0.0, [[USIZE]] %arg0.1)
// FIXME #25759 This should also have `nocapture`
#[no_mangle]
pub fn str(_: &[u8]) {
}
-// CHECK: @trait_borrow({}* nonnull %arg0.0, [3 x [[USIZE]]]* noalias readonly dereferenceable({{.*}}) %arg0.1)
+// CHECK: @trait_borrow({}* nonnull align 1 %arg0.0, [3 x [[USIZE]]]* noalias readonly align {{.*}} dereferenceable({{.*}}) %arg0.1)
// FIXME #25759 This should also have `nocapture`
#[no_mangle]
pub fn trait_borrow(_: &Drop) {
}
-// CHECK: @trait_box({}* noalias nonnull, [3 x [[USIZE]]]* noalias readonly dereferenceable({{.*}}))
+// CHECK: @trait_box({}* noalias nonnull align 1, [3 x [[USIZE]]]* noalias readonly align {{.*}} dereferenceable({{.*}}))
#[no_mangle]
pub fn trait_box(_: Box<Drop>) {
}
-// CHECK: { i8*, i8* } @trait_option(i8* noalias %x.0, i8* %x.1)
+// CHECK: { i8*, i8* } @trait_option(i8* noalias align 1 %x.0, i8* %x.1)
#[no_mangle]
pub fn trait_option(x: Option<Box<Drop>>) -> Option<Box<Drop>> {
x
}
-// CHECK: { [0 x i16]*, [[USIZE]] } @return_slice([0 x i16]* noalias nonnull readonly %x.0, [[USIZE]] %x.1)
+// CHECK: { [0 x i16]*, [[USIZE]] } @return_slice([0 x i16]* noalias nonnull readonly align 2 %x.0, [[USIZE]] %x.1)
#[no_mangle]
pub fn return_slice(x: &[u16]) -> &[u16] {
x