https://bugs.llvm.org/show_bug.cgi?id=35337
Bug ID: 35337
Summary: LLD ICF needs to consider exception tables in .xdata
as part of .text equivalence
Product: lld
Version: unspecified
Hardware: PC
OS: Windows NT
Status: NEW
Severity: enhancement
Priority: P
Component: COFF
Assignee: unassignedb...@nondot.org
Reporter: r...@google.com
CC: llvm-bugs@lists.llvm.org
LLD mislinks this program because the .text contents of these two functions are
the same, but the .xdata exception handler table is different:
extern "C" void __ImageBase() noexcept(false);
void __declspec(dllexport) foo() {
try {
__ImageBase();
} catch (int) {
}
}
void __declspec(dllexport) baz() {
try {
__ImageBase();
} catch (double) {
}
}
Compile and link like so, and observe that the export RVAs are the same:
$ clang-cl -EHsc -O1 -MD t.cpp -c && lld-link t.obj -dll -noentry -opt:icf
-force
C:\src\llvm-project\build\bin\lld-link.exe: warning: t.obj: undefined symbol:
__CxxFrameHandler3
C:\src\llvm-project\build\bin\lld-link.exe: warning:
msvcrt.lib(delete_scalar.obj): undefined symbol: free
$ llvm-readobj -coff-exports t.dll
File: t.dll
Format: COFF-x86-64
Arch: x86_64
AddressSize: 64bit
Export {
Ordinal: 0
Name:
RVA: 0x0
}
Export {
Ordinal: 1
Name: ?baz@@YAXXZ
RVA: 0x6000
}
Export {
Ordinal: 2
Name: ?foo@@YAXXZ
RVA: 0x6000
}
If this were a full working program, bar would not be able to catch exceptions
of type double thrown from __ImageBase and would incorrectly catch 'int'
exceptions.
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