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[lld-macho] Fix bugs around EH_Frame symbols 

While extending the map file to cover unwind info, I realized we had two
issues with our EH_Frame symbols:

1. Their size was not set
2. We would create two EH_Frame symbols per frame when we only needed
   one. This was because the Defined constructor would add the symbol
   itself to InputSection::symbols, but we were also manually appending
   the symbol to that same vector.

Note that ld64 prints "CIE" and "FDE for: <function>" instead of just
"EH_Frame", but I'm punting on that for now unless we discover that
users really depend upon it.

Reviewed By: #lld-macho, Roger

Differential Revision: https://reviews.llvm.org/D137370
This commit is contained in:
Jez Ng 2022-11-08 16:33:32 -05:00
parent 7f0779967f
commit 1a2bc103bb
2 changed files with 20 additions and 15 deletions
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10
lld/MachO/InputFiles.cpp
View File

@ -1347,11 +1347,11 @@ void ObjFile::registerEhFrames(Section &ehFrameSection) {
// that all EH frames have an associated symbol so that we can generate
// subtractor relocs that reference them.
if (isec->symbols.size() == 0)
isec->symbols.push_back(make<Defined>(
"EH_Frame", isec->getFile(), isec, /*value=*/0, /*size=*/0,
/*isWeakDef=*/false, /*isExternal=*/false, /*isPrivateExtern=*/false,
/*includeInSymtab=*/false, /*isThumb=*/false,
/*isReferencedDynamically=*/false, /*noDeadStrip=*/false));
make<Defined>("EH_Frame", isec->getFile(), isec, /*value=*/0,
isec->getSize(), /*isWeakDef=*/false, /*isExternal=*/false,
/*isPrivateExtern=*/false, /*includeInSymtab=*/false,
/*isThumb=*/false, /*isReferencedDynamically=*/false,
/*noDeadStrip=*/false);
else if (isec->symbols[0]->value != 0)
fatal("found symbol at unexpected offset in __eh_frame");

25
lld/test/MachO/map-file.s
View File

@ -8,7 +8,9 @@
# RUN: --time-trace -o %t/test
# RUN: llvm-objdump --syms --section-headers %t/test > %t/objdump
## Check that symbols in cstring sections aren't emitted
# RUN: cat %t/objdump %t/map | FileCheck %s --implicit-check-not _hello_world
## Also check that we don't have redundant EH_Frame symbols (regression test)
# RUN: cat %t/objdump %t/map | FileCheck %s --implicit-check-not _hello_world \
# RUN: --implicit-check-not EH_Frame
# RUN: FileCheck %s --check-prefix=MAPFILE < %t/test.time-trace
# CHECK: Sections:
@ -44,15 +46,18 @@
# CHECK-NEXT: 0x[[#%X,BSS]] 0x{{[0-9A-F]+}} __DATA __common
# CHECK-NEXT: # Symbols:
# CHECK-NEXT: # Address Size File Name
# CHECK-DAG: 0x[[#%X,MAIN]] 0x00000001 [ 1] _main
# CHECK-DAG: 0x[[#%X,BAR]] 0x00000001 [ 1] _bar
# CHECK-DAG: 0x[[#%X,FOO]] 0x00000001 [ 2] __ZTIN3foo3bar4MethE
# CHECK-DAG: 0x[[#%X,HIWORLD]] 0x0000000E [ 3] literal string: Hello world!\n
# CHECK-DAG: 0x[[#%X,HIITSME]] 0x0000000F [ 3] literal string: Hello, it's me
# CHECK-DAG: 0x[[#%X,HIITSME + 0xf]] 0x0000000E [ 3] literal string: Hello world!\n
# CHECK-DAG: 0x[[#%X,NUMBER]] 0x00000001 [ 1] _number
# CHECK-DAG: 0x[[#%X,UNWIND]] 0x0000103C [ 0] compact unwind info
# CHECK-NEXT: # Address Size File Name
# CHECK-DAG: 0x[[#%X,MAIN]] 0x00000001 [ 1] _main
# CHECK-DAG: 0x[[#%X,BAR]] 0x00000001 [ 1] _bar
# CHECK-DAG: 0x[[#%X,FOO]] 0x00000001 [ 2] __ZTIN3foo3bar4MethE
# CHECK-DAG: 0x[[#%X,HIWORLD]] 0x0000000E [ 3] literal string: Hello world!\n
# CHECK-DAG: 0x[[#%X,HIITSME]] 0x0000000F [ 3] literal string: Hello, it's me
# CHECK-DAG: 0x[[#%X,HIITSME + 0xf]] 0x0000000E [ 3] literal string: Hello world!\n
# CHECK-DAG: 0x[[#%X,NUMBER]] 0x00000001 [ 1] _number
# CHECK-DAG: 0x[[#%X,UNWIND]] 0x0000103C [ 0] compact unwind info
## Note: ld64 prints "CIE" and "FDE for: <function>" instead of "EH_Frame".
# CHECK-DAG: 0x[[#%X,EH_FRAME]] 0x00000018 [ 1] EH_Frame
# CHECK-DAG: 0x[[#%X,EH_FRAME + 0x18]] 0x00000020 [ 1] EH_Frame
# MAPFILE: "name":"Total Write map file"