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[ELF] -Map: Print symbols which needs canonical PLT entry/copy relocation just once 

If a copy related symbol (say `copy`) is referenced in two .o
files, this change removes a duplicated line from the -Map output:

```
          202470           202470        1     1 .bss.rel.ro
          202470           202470        1     1         <internal>:(.bss.rel.ro)
          202470           202470        1     1                 copy
removed   202470           202470        1     1                 copy
```

Differential Revision: https://reviews.llvm.org/D115697
This commit is contained in:
Fangrui Song 2021-12-14 10:31:06 -08:00
parent e0aa2ea661
commit 6a44013b0e
2 changed files with 60 additions and 1 deletions
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9
lld/ELF/MapFile.cpp
View File

@ -72,10 +72,17 @@ static SymbolMapTy getSectionSyms(ArrayRef<Defined *> syms) {
// Sort symbols by address. We want to print out symbols in the
// order in the output file rather than the order they appeared
// in the input files.
for (auto &it : ret)
SmallPtrSet<Defined *, 4> set;
for (auto &it : ret) {
// Deduplicate symbols which need a canonical PLT entry/copy relocation.
set.clear();
llvm::erase_if(it.second,
[&](Defined *sym) { return !set.insert(sym).second; });
llvm::stable_sort(it.second, [](Defined *a, Defined *b) {
return a->getVA() < b->getVA();
});
}
return ret;
}

52
lld/test/ELF/map-file-copy.s Normal file
View File

@ -0,0 +1,52 @@
# REQUIRES: x86
# RUN: split-file %s %t
# RUN: llvm-mc -filetype=obj -triple=x86_64 %t/1.s -o %t/1.o
# RUN: llvm-mc -filetype=obj -triple=x86_64 %t/2.s -o %t/2.o
# RUN: llvm-mc -filetype=obj -triple=x86_64 %t/3.s -o %t/3.o
# RUN: ld.lld -shared -soname=3 --version-script=%t/3.ver %t/3.o -o %t/3.so
# RUN: ld.lld -Map=%t/1.map %t/1.o %t/2.o %t/3.so -o %t/1
# RUN: FileCheck %s --input-file=%t/1.map
## Both TUs reference func/copy which need a canonical PLT entry/copy relocation.
## Test we print func/copy just once.
# CHECK: {{ }}.plt
# CHECK-NEXT: <internal>:(.plt)
# CHECK-NEXT: func@v1{{$}}
# CHECK-NEXT: .dynamic
# CHECK: .bss.rel.ro
# CHECK-NEXT: <internal>:(.bss.rel.ro)
## Ideally this is displayed as copy@v2.
# CHECK-NEXT: copy{{$}}
# CHECK-NEXT: .got.plt
#--- 1.s
.global _start
_start:
.symver func, func@@@v1
mov $copy, %eax
mov $func - ., %eax
#--- 2.s
.symver func, func@@@v1
mov $copy, %eax
mov $func - ., %eax
#--- 3.s
.globl func
.symver func, func@v1, remove
.type func, @function
func:
ret
.section .rodata,"a"
.globl copy
.type copy, @object
copy:
.byte 1
.size copy, 1
#--- 3.ver
v1 { func; };
v2 { copy; };