summaryrefslogtreecommitdiffstats
path: root/build/build-clang/llvmorg-17-init-2171-g8198f30f7e75.patch
diff options
context:
space:
mode:
Diffstat (limited to 'build/build-clang/llvmorg-17-init-2171-g8198f30f7e75.patch')
-rw-r--r--build/build-clang/llvmorg-17-init-2171-g8198f30f7e75.patch99
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
+