[PATCH] D127812: [AArch64] FMV support and necessary target features dependencies.

[Mitch Phillips via Phabricator via cfe-commits]

hctim added a comment.

In D127812#4011372 <https://reviews.llvm.org/D127812#4011372>, @ilinpv wrote:

> Regular builds works fine for me, pthreads located here "/lib/x86_64-linux-gnu/libpthread.so" "/usr/lib/x86_64-linux-gnu/libpthread.so". Enabling "-DLLVM_USE_SANITIZER=Memory" resulted in many "WARNING: MemorySanitizer: use-of-uninitialized-value" on tblgen like:
>
>   cd /data/ReleasesToCommit/llvm-project/build && /data/ReleasesToCommit/llvm-project/build/bin/llvm-tblgen -gen-intrinsic-enums -intrinsic-prefix=s390 -I /data/ReleasesToCommit/llvm-project/llvm/include/llvm/IR -I/data/ReleasesToCommit/llvm-project/build/include -I/data/ReleasesToCommit/llvm-project/llvm/include /data/ReleasesToCommit/llvm-project/llvm/include/llvm/IR/Intrinsics.td --write-if-changed -o include/llvm/IR/IntrinsicsS390.h -d include/llvm/IR/IntrinsicsS390.h.d
>   [build] ==2441251==WARNING: MemorySanitizer: use-of-uninitialized-value

Yeah that's a false-positive because of bad-ordering. MSan is much tricker because it requires an instrumented libcxx. If you can't use the buildscript, an MVP for the right ordering should be something like:

1. Build a new clang.

  $ cd /tmp/1/
  $ cmake \
  -DLLVM_ENABLE_PROJECTS="clang;compiler-rt;lld" \
  -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" \
  -DCMAKE_C_COMPILER=clang \
  -DCMAKE_CXX_COMPILER=clang++ \
  -GNinja \
  -DCMAKE_BUILD_TYPE=Release \
  -DLLVM_USE_LINKER=lld \
  -DCMAKE_C_FLAGS="-Wall" \
  -DCMAKE_CXX_FLAGS="-Wall" \
  /path/to/llvm/llvm
  $ ninja clang lld compiler-rt llvm-symbolizer



2. Build a sanitizer libcxx.

  $ cd /tmp/2
  $ cmake \
  -DCMAKE_C_COMPILER=/tmp/1/bin/clang \
  -DCMAKE_CXX_COMPILER=/tmp/1/bin/clang++ \
  -GNinja \
  -DLLVM_USE_SANITIZER=Memory \
  -DCMAKE_BUILD_TYPE=Release \
  -DLLVM_ENABLE_ASSERTIONS=ON \
  -DLLVM_ENABLE_RUNTIMES="'libcxx;libcxxabi'" \
  -DLLVM_USE_LINKER="'lld'" \
  /path/to/llvm/runtimes/ # <-------- Make sure this is *runtimes*, not llvm.
  $ ninja cxx cxxabi



3. Build a msan-ified clang, and use the libcxx from step 2.

  $ cd /tmp/3
  $ cat .cmake_script.sh
  #!/bin/bash -e
  
  LDFLAGS="-lc++abi"
  LDFLAGS="$LDFLAGS -Wl,--rpath=/tmp/2/lib" # <---- use the instrumented libcxx from step 2
  LDFLAGS="$LDFLAGS -L/tmp/2/lib"
  
  CFLAGS="$LDFLAGS"
  CFLAGS="$CFLAGS -fsanitize=memory"
  CFLAGS="$CFLAGS -nostdinc++"
  CFLAGS="$CFLAGS -isystem /tmp/2/include" # <---- use the instrumented libcxx from step 2
  CFLAGS="$CFLAGS -isystem /tmp/2/include/c++/v1"
  CFLAGS="$CFLAGS -w"
  CFLAGS="$CFLAGS -fsanitize-memory-use-after-dtor -fsanitize-memory-param-retval"
  
  USE_SANITIZER="Memory"
  # USE_SANITIZER="MemoryWithOrigins"  # <-------------------+-- uncomment these and comment the USE_SANITIZER="Memory" above to get track-origins.
  # CFLAGS="$CFLAGS -fsanitize-memory-track-origins=2"  # <--+
  
  cmake \
  -DCMAKE_C_COMPILER=/tmp/1/bin/clang \
  -DCMAKE_CXX_COMPILER=/tmp/1/bin/clang++ \
  -DLLVM_ENABLE_LIBCXX=ON \
  -GNinja \
  -DLLVM_USE_SANITIZER="$USE_SANITIZER" \
  -DCMAKE_BUILD_TYPE=Release \
  -DLLVM_ENABLE_ASSERTIONS=ON \
  -DCMAKE_C_FLAGS="$CFLAGS" \
  -DCMAKE_CXX_FLAGS="$CFLAGS" \
  -DCMAKE_EXE_LINKER_FLAGS="$LDFLAGS" \
  -DLLVM_ENABLE_PROJECTS="clang;lld;clang-tools-extra" \
  -DLLVM_USE_LINKER="lld" \
  /path/to/llvm/llvm
  $ . .cmake_script.sh
  $ ninja clang lld
  $ ninja check-clang check-llvm # <----- finally, run your tests


Repository:
  rG LLVM Github Monorepo

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