================
@@ -133,6 +133,17 @@ CreateCI(const llvm::opt::ArgStringList &Argv) {
// times, reusing the same AST.
Clang->getCodeGenOpts().ClearASTBeforeBackend = false;
+ // Clang emits direct PC-relative accesses for external data (e.g. C++
+ // type-info used by exception handling). As clang-repl directly mmap()s
+ // shared objects into memory, the target symbol may be more than 2GB away
+ // from the generated code, resulting in an out-of-range Delta32/PC32
+ // relocation. Force GOT-based access instead so the relocation remains
+ // within range.
+ //
+ // Unlike -fPIC, this does not define __PIC__ and remains compatible with
+ // precompiled headers.
+ Clang->getCodeGenOpts().DirectAccessExternalData = false;
----------------
aokblast wrote:
My understanding is that it uses the following pattern:
```
mov foo@GOTPCREL(%rip), %rax
mov (%rax), %eax
```
The origianl PC relative is:
```
lea foo(%rip), %rax
```
It definitely introduces some performance difference, but it is the correct way
to handle R_*_32 relocations. In a static linker, simple cases are resolved
directly, while others are handled using R_*_COPY or R_*_GLOB_DAT relocations,
which can target symbols beyond the 2GB range.
https://github.com/llvm/llvm-project/pull/201286
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