[llvm-branch-commits] [lld] edf6447 - [ELF][PPC64] Fix assertion failure for branches to hidden undefined weak for -no-pie
Fangrui Song via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Tue Feb 15 13:01:02 PST 2022
Author: Fangrui Song
Date: 2022-02-15T12:58:24-08:00
New Revision: edf64474d66286a7f5578a033d1c3ccb31f2a2a7
URL: https://github.com/llvm/llvm-project/commit/edf64474d66286a7f5578a033d1c3ccb31f2a2a7
DIFF: https://github.com/llvm/llvm-project/commit/edf64474d66286a7f5578a033d1c3ccb31f2a2a7.diff
LOG: [ELF][PPC64] Fix assertion failure for branches to hidden undefined weak for -no-pie
Reported by Stefan Pintilie in D119773.
For a branch to a hidden undefined weak symbol, there is an
`assert(sym->getVA());` failure in PPC64LongBranchTargetSection::writeTo for a
-no-pie link. The root cause is that we unnecessarily create the thunk for the
-no-pie link.
Fix this by changing the condition to just `s.isUndefined()`. See the inline
comment.
Rename ppc64-weak-undef-call.s to ppc64-undefined-weak.s to be consistent with
other architectures.
Reviewed By: sfertile, stefanp
Differential Revision: https://reviews.llvm.org/D119787
(cherry picked from commit 53b59fdc52bf6c8bf15ce7c146d2cebe338f34a7)
Added:
lld/test/ELF/ppc64-undefined-weak.s
lld/test/ELF/ppc64-undefined.s
Modified:
lld/ELF/Arch/PPC64.cpp
Removed:
lld/test/ELF/ppc64-weak-undef-call-shared.s
lld/test/ELF/ppc64-weak-undef-call.s
################################################################################
diff --git a/lld/ELF/Arch/PPC64.cpp b/lld/ELF/Arch/PPC64.cpp
index c083484f42804..7d051c43af0d3 100644
--- a/lld/ELF/Arch/PPC64.cpp
+++ b/lld/ELF/Arch/PPC64.cpp
@@ -1380,9 +1380,10 @@ bool PPC64::needsThunk(RelExpr expr, RelType type, const InputFile *file,
if (type == R_PPC64_REL24_NOTOC && (s.stOther >> 5) > 1)
return true;
- // If a symbol is a weak undefined and we are compiling an executable
- // it doesn't need a range-extending thunk since it can't be called.
- if (s.isUndefWeak() && !config->shared)
+ // An undefined weak symbol not in a PLT does not need a thunk. If it is
+ // hidden, its binding has been converted to local, so we just check
+ // isUndefined() here. A undefined non-weak symbol has been errored.
+ if (s.isUndefined())
return false;
// If the offset exceeds the range of the branch type then it will need
diff --git a/lld/test/ELF/ppc64-undefined-weak.s b/lld/test/ELF/ppc64-undefined-weak.s
new file mode 100644
index 0000000000000..7b1be5e36dd32
--- /dev/null
+++ b/lld/test/ELF/ppc64-undefined-weak.s
@@ -0,0 +1,40 @@
+# REQUIRES: ppc
+
+# RUN: llvm-mc -filetype=obj -triple=powerpc64le %s -o %t.o
+# RUN: ld.lld %t.o -o %t
+# RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s --check-prefix=PDE
+# RUN: ld.lld -pie %t.o -o %t
+# RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s --check-prefix=PIC
+# RUN: ld.lld -shared %t.o -o %t.so
+# RUN: llvm-objdump -d --no-show-raw-insn %t.so | FileCheck %s --check-prefix=PIC
+
+# RUN: llvm-mc -filetype=obj -triple=powerpc64 %s -o %t.o
+# RUN: ld.lld %t.o -o %t
+# RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s --check-prefix=PDE
+
+## Branches to an undefined weak symbol need a thunk iff a dynamic relocation is
+## produced. undefweak2 is hidden and does not need a dynamic relocation, so we
+## suppress the thunk. undefweak1 needs a thunk iff -pie or -shared.
+
+# PDE-LABEL: <_start>:
+# PDE-NEXT: bl {{.*}} <_start>
+# PDE-NEXT: nop
+# PDE-NEXT: bl {{.*}} <_start+0x8>
+# PDE-NEXT: nop
+
+# PIC-LABEL: <_start>:
+# PIC-NEXT: bl {{.*}} <__plt_undefweak1>
+# PIC-NEXT: ld 2, 24(1)
+# PIC-NEXT: bl {{.*}} <_start+0x8>
+# PIC-NEXT: nop
+
+.text
+.global _start
+_start:
+ bl undefweak1
+ nop
+ bl undefweak2
+ nop
+
+.weak undefweak1, undefweak2
+.hidden undefweak2
diff --git a/lld/test/ELF/ppc64-undefined.s b/lld/test/ELF/ppc64-undefined.s
new file mode 100644
index 0000000000000..c9c2a7564f95f
--- /dev/null
+++ b/lld/test/ELF/ppc64-undefined.s
@@ -0,0 +1,11 @@
+# REQUIRES: ppc
+
+# RUN: llvm-mc -filetype=obj -triple=powerpc64le %s -o %t.o
+# RUN: not ld.lld %t.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR
+
+# ERR: error: undefined symbol: undef
+
+.global _start
+_start:
+ bl undef
+ nop
diff --git a/lld/test/ELF/ppc64-weak-undef-call-shared.s b/lld/test/ELF/ppc64-weak-undef-call-shared.s
deleted file mode 100644
index 244f72f995737..0000000000000
--- a/lld/test/ELF/ppc64-weak-undef-call-shared.s
+++ /dev/null
@@ -1,21 +0,0 @@
-# REQUIRES: ppc
-
-# RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s -o %t.o
-# RUN: ld.lld -shared %t.o -o %t.so
-# RUN: llvm-readobj --symbols -r --dyn-syms %t.so | FileCheck %s
-
-# RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o %t.o
-# RUN: ld.lld -shared %t.o -o %t.so
-# RUN: llvm-readobj --symbols -r --dyn-syms %t.so | FileCheck %s
-
-.section ".toc","aw"
-.quad weakfunc
-// CHECK-NOT: R_PPC64_RELATIVE
-
-.text
-.Lfoo:
- bl weakfunc
- nop
-// CHECK-NOT: R_PPC64_REL24
-
-.weak weakfunc
diff --git a/lld/test/ELF/ppc64-weak-undef-call.s b/lld/test/ELF/ppc64-weak-undef-call.s
deleted file mode 100644
index 1f6869311708c..0000000000000
--- a/lld/test/ELF/ppc64-weak-undef-call.s
+++ /dev/null
@@ -1,29 +0,0 @@
-# REQUIRES: ppc
-
-# RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s -o %t
-# RUN: ld.lld %t -o %t2
-# RUN: llvm-objdump -d --no-show-raw-insn %t2 | FileCheck %s
-
-# RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o %t
-# RUN: ld.lld %t -o %t2
-# RUN: llvm-objdump -d --no-show-raw-insn %t2 | FileCheck %s
-
-# CHECK: Disassembly of section .text:
-# CHECK-EMPTY:
-
-.text
-.global _start
-_start:
- bl weakfunc
- nop
- blr
-
-.weak weakfunc
-
-# It does not really matter how we fixup the bl, if at all, because it needs to
-# be unreachable. But, we should link successfully. We should not, however,
-# generate a .plt entry (this would be wasted space). For now, we do nothing
-# (leaving the zero relative offset present in the input).
-# CHECK: 10010158: bl 0x10010158
-# CHECK: 1001015c: nop
-# CHECK: 10010160: blr
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