danielkiss added inline comments.
================
Comment at: llvm/lib/IR/AutoUpgrade.cpp:4415-4430
- // Upgrade branch protection and return address signing module flags. The
- // module flag behavior for these fields were Error and now they are Min.
- if (ID->getString() == "branch-target-enforcement" ||
- ID->getString().startswith("sign-return-address")) {
- if (auto *Behavior =
- mdconst::dyn_extract_or_null<ConstantInt>(Op->getOperand(0))) {
- if (Behavior->getLimitedValue() == Module::Error) {
----------------
MaskRay wrote:
> danielkiss wrote:
> > In a full LTO build the linker will complain about the mis match between
> > the flags if one of the objects compiled with an older compiler that
> > emitted `Module:Error` for these flags.
> The new approach doesnot emit a flag for 0 value, so there won't be an error
> even with old bitcode files using `Error`.
older compiler could emit `Module:Error` with 0 and with this patch we emit 1
with `min` so the linker will stop with
`ld.lld: error: linking module flags 'branch-target-enforcement': IDs have
conflicting behaviors in 'foo.o' and 'ld-temp.o'`
```
clang++-13 -flto=full -c foo.cpp -o foo.o
../build/bin/clang++ -flto=full -c main.cpp -o main.o
-mbranch-protection=standard
../build/bin/clang++ -fuse-ld=lld main.o foo.o -o a.out
```
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D130145/new/
https://reviews.llvm.org/D130145
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