From 6950242b1cfff94eda669f65bf082c54fde5e90f Mon Sep 17 00:00:00 2001 From: "Felix S. Klock II" Date: Thu, 15 Sep 2016 19:02:10 +0200 Subject: [PATCH] Workaround #34427 by using memset of 0 on ARM to set the discriminant. --- src/librustc_trans/adt.rs | 25 +++++++++++++++++++++---- src/test/run-pass/issue-34427.rs | 26 ++++++++++++++++++++++++++ 2 files changed, 47 insertions(+), 4 deletions(-) create mode 100644 src/test/run-pass/issue-34427.rs diff --git a/src/librustc_trans/adt.rs b/src/librustc_trans/adt.rs index e8498363e45a3..050b5127e6acf 100644 --- a/src/librustc_trans/adt.rs +++ b/src/librustc_trans/adt.rs @@ -54,6 +54,7 @@ use syntax::ast; use syntax::attr; use syntax::attr::IntType; use abi::FAT_PTR_ADDR; +use base; use build::*; use common::*; use debuginfo::DebugLoc; @@ -963,16 +964,32 @@ pub fn trans_set_discr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>, Store(bcx, C_null(llptrty), val); } } - StructWrappedNullablePointer { nndiscr, ref discrfield, .. } => { + StructWrappedNullablePointer { nndiscr, ref discrfield, ref nonnull, .. } => { if discr != nndiscr { - let llptrptr = GEPi(bcx, val, &discrfield[..]); - let llptrty = val_ty(llptrptr).element_type(); - Store(bcx, C_null(llptrty), llptrptr); + if target_sets_discr_via_memset(bcx) { + // Issue #34427: As workaround for LLVM bug on + // ARM, use memset of 0 on whole struct rather + // than storing null to single target field. + let b = B(bcx); + let llptr = b.pointercast(val, Type::i8(b.ccx).ptr_to()); + let fill_byte = C_u8(b.ccx, 0); + let size = C_u64(b.ccx, nonnull.size); + let align = C_u32(b.ccx, nonnull.align); + base::call_memset(&b, llptr, fill_byte, size, align, false); + } else { + let llptrptr = GEPi(bcx, val, &discrfield[..]); + let llptrty = val_ty(llptrptr).element_type(); + Store(bcx, C_null(llptrty), llptrptr); + } } } } } +fn target_sets_discr_via_memset<'blk, 'tcx>(bcx: Block<'blk, 'tcx>) -> bool { + bcx.sess().target.target.arch == "arm" || bcx.sess().target.target.arch == "aarch64" +} + fn assert_discr_in_range(ity: IntType, min: Disr, max: Disr, discr: Disr) { match ity { attr::UnsignedInt(_) => { diff --git a/src/test/run-pass/issue-34427.rs b/src/test/run-pass/issue-34427.rs new file mode 100644 index 0000000000000..6bf8a2ac6a72d --- /dev/null +++ b/src/test/run-pass/issue-34427.rs @@ -0,0 +1,26 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// Issue #34427: On ARM, the code in `foo` at one time was generating +// a machine code instruction of the form: `str r0, [r0, rN]!` (for +// some N), which is not legal because the source register and base +// register cannot be identical in the preindexed form signalled by +// the `!`. +// +// See LLVM bug: https://llvm.org/bugs/show_bug.cgi?id=28809 + +#[inline(never)] +fn foo(n: usize) -> Vec> { + (0..n).map(|_| None).collect() +} + +fn main() { + let _ = (foo(10), foo(32)); +}