Use local labels for inline asm

[okhowang]

Description

• Type: Bug
• Priority: Blocker

---

Bug

OS
iPhoneSimulator

mbed TLS build:
Version: 2.22.0
OS version: 9.0
Configuration: default
Compiler and options (if you used a pre-built binary, please indicate how you obtained it): Xcode 11.5
Additional environment information:

Expected behavior
building success
Actual behavior
got error when linking

<inline asm>:9:2: error: invalid symbol redefinition
        unsupported:              
        ^
LLVM ERROR: Error parsing inline asm

clang: error: linker command failed with exit code 1 (use -v to see invocation)

unsupported: is located in padlock.c which use named labels in inline asm.
Steps to reproduce
I can't make an reproducible minimized project.
but according https://stackoverflow.com/questions/14506151/invalid-symbol-redefinition-in-inline-asm-on-llvm.
we should use local labels for inline asm, not named labels.

[gilles-peskine-arm]

What version of Clang is invoked and with what options? I'm asking so that we can try to reproduce this. We have a macOS build on our CI (Clang 9.1.0) that just runs make and it isn't complaining.

[okhowang]

$ clang --version
Apple clang version 11.0.3 (clang-1103.0.32.62)
Target: x86_64-apple-darwin19.5.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

[okhowang]

I add some extra parameter in my project, but i can't reproduce in mbedtls project.

cmake_policy(SET CMP0069 NEW)
cmake_policy(SET CMP0063 NEW)
set(CMAKE_C_VISIBILITY_PRESET hidden)
set(CMAKE_CXX_VISIBILITY_PRESET hidden)
set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
set(CMAKE_INTERPROCEDURAL_OPTIMIZATION ON)
set(CMAKE_POSITION_INDEPENDENT_CODE ON)
set(CMAKE_XCODE_ATTRIBUTE_ENABLE_BITCODE YES)

[gilles-peskine-arm]

Maybe set(CMAKE_INTERPROCEDURAL_OPTIMIZATION ON) turns on link-time optimization and clang decides to inline mbedtls_padlock_has_support in both places where it's called in aes.c. Our CI build doesn't turn on LTO anywhere AFAIR, maybe we should add this. I'll give it a try.

[gilles-peskine-arm]

clang-10 -O3 -flto on Linux doesn't complain. I don't have Clang 11 easily accessible. Can you share the compiler command line that results from these cmake settings?

[okhowang]

I'm building iOS library on macOS.
sorry for unable to provide compiler command detailly