diff options
Diffstat (limited to 'build/build-clang/llvmorg-17-init-2171-g8198f30f7e75.patch')
| -rw-r--r-- | build/build-clang/llvmorg-17-init-2171-g8198f30f7e75.patch | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/build/build-clang/llvmorg-17-init-2171-g8198f30f7e75.patch b/build/build-clang/llvmorg-17-init-2171-g8198f30f7e75.patch new file mode 100644 index 0000000000..408e83fbb5 --- /dev/null +++ b/build/build-clang/llvmorg-17-init-2171-g8198f30f7e75.patch @@ -0,0 +1,99 @@ +From 8198f30f7e756e3368c3eda62ecc3d0cc62d1570 Mon Sep 17 00:00:00 2001 +From: Jez Ng <jezng@fb.com> +Date: Tue, 14 Feb 2023 14:34:19 -0500 +Subject: [PATCH] [lld-macho] Account for alignment in thunk insertion + algorithm + +We previously neglected this, leading us to underestimate the maximum +possible branch address offset. + +Fixing this should allow us to reduce `slop` to more reasonable +levels. I've lowered it to 256 for now, though I suspect we could go +lower. + +Fixes https://github.com/llvm/llvm-project/issues/59259. + +Reviewed By: serge-sans-paille + +Differential Revision: https://reviews.llvm.org/D144029 +--- + lld/MachO/ConcatOutputSection.cpp | 10 +++-- + lld/test/MachO/arm64-thunk-for-alignment.s | 44 ++++++++++++++++++++++ + 2 files changed, 51 insertions(+), 3 deletions(-) + create mode 100644 lld/test/MachO/arm64-thunk-for-alignment.s + +diff --git a/lld/MachO/ConcatOutputSection.cpp b/lld/MachO/ConcatOutputSection.cpp +index cbd3a2492d25..b522bd9b289e 100644 +--- a/lld/MachO/ConcatOutputSection.cpp ++++ b/lld/MachO/ConcatOutputSection.cpp +@@ -246,10 +246,14 @@ void TextOutputSection::finalize() { + // contains several branch instructions in succession, then the distance + // from the current position to the position where the thunks are inserted + // grows. So leave room for a bunch of thunks. +- unsigned slop = 1024 * thunkSize; +- while (finalIdx < endIdx && addr + size + inputs[finalIdx]->getSize() < +- isecVA + forwardBranchRange - slop) ++ unsigned slop = 256 * thunkSize; ++ while (finalIdx < endIdx) { ++ size_t expectedNewSize = alignTo(addr + size, inputs[finalIdx]->align) + ++ inputs[finalIdx]->getSize(); ++ if (expectedNewSize >= isecVA + forwardBranchRange - slop) ++ break; + finalizeOne(inputs[finalIdx++]); ++ } + + if (!isec->hasCallSites) + continue; +diff --git a/lld/test/MachO/arm64-thunk-for-alignment.s b/lld/test/MachO/arm64-thunk-for-alignment.s +new file mode 100644 +index 000000000000..f497b81f705b +--- /dev/null ++++ b/lld/test/MachO/arm64-thunk-for-alignment.s +@@ -0,0 +1,44 @@ ++# REQUIRES: aarch64 ++# RUN: rm -rf %t; split-file %s %t ++# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %t/foo.s -o %t/foo.o ++# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %t/bar.s -o %t/bar.o ++# RUN: %lld -dylib -arch arm64 -lSystem -o %t/out %t/foo.o %t/bar.o ++ ++# RUN: llvm-objdump --macho --syms %t/out | FileCheck %s ++# CHECK: _bar.thunk.0 ++ ++## Regression test for PR59259. Previously, we neglected to check section ++## alignments when deciding when to create thunks. ++ ++## If we ignore alignment, the total size of _spacer1 + _spacer2 below is just ++## under the limit at which we attempt to insert thunks between the spacers. ++## However, with alignment accounted for, their total size ends up being ++## 0x8000000, which is just above the max forward branch range, making thunk ++## insertion necessary. Thus, not accounting for alignment led to an error. ++ ++#--- foo.s ++ ++_foo: ++ b _bar ++ ++## Size of a `b` instruction. ++.equ callSize, 4 ++## Refer to `slop` in TextOutputSection::finalize(). ++.equ slopSize, 12 * 256 ++ ++_spacer1: ++ .space 0x4000000 - slopSize - 2 * callSize - 1 ++ ++.subsections_via_symbols ++ ++#--- bar.s ++.globl _bar ++ ++.p2align 14 ++_spacer2: ++ .space 0x4000000 ++ ++_bar: ++ ret ++ ++.subsections_via_symbols +-- +2.39.0.1.g6739ec1790 + |