Summary:
The bug triggers when the following conditions are met:
- A thunk is created in a given input section S
- A linker script is specified
- There is at least one matcher in the linker script .text section output
that does not match any of the sections in the input files, before the matcher
that matches section S.
The issue was found when linking the FreeBSD kernel for MIPS when built
with -fPIC. Patch by Alfredo Mazzinghi.
Reviewers: ruiu, psmith, atanasyan
Reviewed By: ruiu
Subscribers: peter.smith, emaste, sdardis, krytarowski, llvm-commits
Differential Revision: https://reviews.llvm.org/D40174
llvm-svn: 318653
OutputSection *TOS = IS->getParent();
for (BaseCommand *BC : TOS->SectionCommands)
if (auto *ISD = dyn_cast<InputSectionDescription>(BC)) {
+ if (ISD->Sections.empty())
+ continue;
InputSection *first = ISD->Sections.front();
InputSection *last = ISD->Sections.back();
if (IS->OutSecOff >= first->OutSecOff &&
--- /dev/null
+# REQUIRES: mips
+# RUN: llvm-mc -filetype=obj -defsym=MAIN=1 -triple=mips-unknown-freebsd %s -o %t
+# RUN: llvm-mc -filetype=obj -defsym=TARGET=1 -triple=mips-unknown-freebsd %s -o %t1
+
+# SECTIONS command with the first pattern that does not match.
+# Linking a PIC and non-PIC object files triggers the LA25 thunk generation.
+# RUN: echo "SECTIONS { \
+# RUN: .text : { \
+# RUN: *(.nomatch) \
+# RUN: %t(.text) \
+# RUN: . = . + 0x100000 ; \
+# RUN: %t1(.text) \
+# RUN: } \
+# RUN: }" > %t.script
+# RUN: ld.lld -o %t.exe --script %t.script %t %t1
+# RUN: llvm-objdump -t %t.exe | FileCheck %s
+# CHECK: SYMBOL TABLE:
+# CHECK-ANY: 00000000 .text 00000000 _start
+# CHECK-ANY: 0010000c l F .text 00000010 __LA25Thunk_too_far
+# CHECK-ANY: 00100020 g F .text 00000024 too_far
+
+.ifdef MAIN
+.global _start
+_start:
+ j too_far
+ nop
+.endif
+
+.ifdef TARGET
+ .text
+ .abicalls
+ .set noreorder
+ .globl too_far
+ .ent too_far
+too_far:
+ nop
+ jr $ra
+ nop
+ .end too_far
+.endif