From 781d64cbcfc18effc2b4786d41cc2fbcaa5dc0d0 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 08:46:37 -0700
Subject: [PATCH 01/11] initial commit

---
 bootstrap.sh | 138 +++++++++++++++++++++++++++++++++++++++++++++++++++
 test_lib.sh  |  24 +++++++++
 2 files changed, 162 insertions(+)
 create mode 100755 bootstrap.sh
 create mode 100755 test_lib.sh

diff --git a/bootstrap.sh b/bootstrap.sh
new file mode 100755
index 0000000..20846ea
--- /dev/null
+++ b/bootstrap.sh
@@ -0,0 +1,138 @@
+set -eu
+
+LLVM_URL=https://github.com/llvm/llvm-project.git
+LINUX_URL=https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+MUSL_URL=git://git.musl-libc.org/musl
+
+function update_llvm () {
+  pushd llvm-project
+  git fetch --depth 1
+  git reset --hard origin/main
+  popd
+}
+
+function fetch_llvm () {
+  git clone --depth=1 $LLVM_URL --branch main --single-branch
+}
+
+function get_or_fetch_llvm () {
+  if [[ -d llvm-project ]]; then
+    update_llvm
+  else
+    fetch_llvm
+  fi;
+}
+
+function update_linux () {
+  pushd linux
+  git fetch --depth 1
+  git reset --hard origin/master
+  popd
+}
+
+function fetch_linux () {
+  git clone --depth=1 $LINUX_URL --branch master --single-branch
+}
+
+function get_or_fetch_linux_kernel () {
+  if [[ -d linux ]]; then
+    update_linux
+  else
+    fetch_linux
+  fi;
+}
+
+function build_kernel_headers () {
+  if [[ -d kernel-headers ]]; then
+    return
+  fi
+
+  pushd linux
+  make LLVM=1 INSTALL_HDR_PATH=../kernel-headers mrproper headers_install -j$(nproc)
+  popd
+}
+
+function bootstrap_compiler_rt () {
+  rm -rf sysroot
+  mkdir -p sysroot
+  SYSROOT=$(readlink -f sysroot)
+  CC=$(which clang)
+  CXX=$(which clang++)
+
+  #rm -rf llvm-project/compiler-rt/build
+  mkdir -p llvm-project/compiler-rt/build
+  pushd llvm-project/compiler-rt/build
+  cmake -D CMAKE_BUILD_TYPE=Release \
+    -D CMAKE_CXX_COMPILER=$CXX \
+    -D CMAKE_CXX_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D CMAKE_C_COMPILER=$CC \
+    -D CMAKE_C_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D COMPILER_RT_BUILD_LIBFUZZER=NO \
+    -D COMPILER_RT_BUILD_MEMPROF=NO \
+    -D COMPILER_RT_BUILD_ORC=NO \
+    -D COMPILER_RT_BUILD_PROFILE=NO \
+    -D COMPILER_RT_BUILD_SANITIZERS=NO \
+    -D COMPILER_RT_BUILD_XRAY=NO \
+    -D COMPILER_RT_DEFAULT_TARGET_TRIPLE=x86_64-unknown-linux-musl \
+    -D LLVM_ENABLE_PROJECTS="compiler-rt;" \
+    -D LLVM_TARGETS_TO_BUILD="X86;" \
+    -G Ninja \
+    -S ..
+    #-D CMAKE_INSTALL_LIBDIR=lib \
+    #-D CMAKE_INSTALL_PREFIX=woof \
+    #-D COMPILER_RT_INSTALL_PATH=woof \
+    #-D COMPILER_RT_INSTALL_LIBRARY_DIR=woof \
+  ninja compiler-rt
+  DESTDIR=$SYSROOT ninja install
+  popd
+}
+
+function update_musl () {
+  pushd musl
+  git fetch --depth 1
+  git reset --hard origin/master
+  popd
+}
+
+function fetch_musl () {
+  git clone --depth=1 $MUSL_URL --branch master --single-branch
+}
+
+function get_or_fetch_musl () {
+  if [[ -d musl ]]; then
+    update_musl
+  else
+    fetch_musl
+  fi;
+}
+
+function build_musl () {
+  BUILTINS=$(readlink -f sysroot/usr/local/lib/linux/libclang_rt.builtins-x86_64.a)
+  CC=$(which clang)
+  SYSROOT=$(readlink -f sysroot)
+  rm -rf musl/build
+  mkdir -p musl/build
+  pushd musl/build
+  LIBCC=$BUILTINS CC=$CC ../configure \
+    --prefix=/usr/local/ \
+    --host=x86_64-unknown-linux-musl \
+    --syslibdir=/usr/local/lib \
+    --disable-static
+
+  make -j$(nproc) AR=llvm-ar RANLIB=llvm-ranlib
+  make DESTDIR=$SYSROOT install-libs install-headers -j$(nproc)
+
+  # TODO: hack
+  pushd $SYSROOT/usr/local/lib
+  ln -sf libc.so ld-musl-x86_64.so.1
+  popd
+  popd
+  ./test_lib.sh
+}
+
+#get_or_fetch_llvm
+bootstrap_compiler_rt
+#get_or_fetch_linux_kernel
+build_kernel_headers
+#get_or_fetch_musl
+build_musl
diff --git a/test_lib.sh b/test_lib.sh
new file mode 100755
index 0000000..9a1e1ef
--- /dev/null
+++ b/test_lib.sh
@@ -0,0 +1,24 @@
+set -eu
+
+cat << EOF > test.c
+#include <stdio.h>
+int main() { puts("hello world"); }
+EOF
+
+# -fuse-ld: use LLD rather than BFD.
+# -rtlib: use compiler-rt rather than libgcc.
+# -Xlinker --dynamic-linker: use musl's dynamic loader as the program
+#                            interperter.
+# --target: use musl rather than glibc.
+# -resource-dir: use our compiler-rt builtins.
+# --sysroot: use our libc headers
+clang test.c \
+  -fuse-ld=lld \
+  -rtlib=compiler-rt \
+  -Xlinker --dynamic-linker=sysroot/usr/local/lib/ld-musl-x86_64.so.1 \
+  --target=x86_64-unknown-linux-musl \
+  -resource-dir=sysroot/usr/local \
+  --sysroot=sysroot/usr/local
+
+./a.out
+rm -f test.c a.out

From e8e6cd9f004d58a381ee8c271b450e6bf43fd664 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 08:55:40 -0700
Subject: [PATCH 02/11] move kernel header to separate script

---
 bootstrap.sh | 33 +--------------------------------
 kernel.sh    | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 32 deletions(-)
 create mode 100755 kernel.sh

diff --git a/bootstrap.sh b/bootstrap.sh
index 20846ea..2a9dd62 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -1,7 +1,6 @@
 set -eu
 
 LLVM_URL=https://github.com/llvm/llvm-project.git
-LINUX_URL=https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
 MUSL_URL=git://git.musl-libc.org/musl
 
 function update_llvm () {
@@ -23,35 +22,6 @@ function get_or_fetch_llvm () {
   fi;
 }
 
-function update_linux () {
-  pushd linux
-  git fetch --depth 1
-  git reset --hard origin/master
-  popd
-}
-
-function fetch_linux () {
-  git clone --depth=1 $LINUX_URL --branch master --single-branch
-}
-
-function get_or_fetch_linux_kernel () {
-  if [[ -d linux ]]; then
-    update_linux
-  else
-    fetch_linux
-  fi;
-}
-
-function build_kernel_headers () {
-  if [[ -d kernel-headers ]]; then
-    return
-  fi
-
-  pushd linux
-  make LLVM=1 INSTALL_HDR_PATH=../kernel-headers mrproper headers_install -j$(nproc)
-  popd
-}
-
 function bootstrap_compiler_rt () {
   rm -rf sysroot
   mkdir -p sysroot
@@ -132,7 +102,6 @@ function build_musl () {
 
 #get_or_fetch_llvm
 bootstrap_compiler_rt
-#get_or_fetch_linux_kernel
-build_kernel_headers
+./kernel.sh
 #get_or_fetch_musl
 build_musl
diff --git a/kernel.sh b/kernel.sh
new file mode 100755
index 0000000..49c46c4
--- /dev/null
+++ b/kernel.sh
@@ -0,0 +1,35 @@
+set -eu
+
+LINUX_URL=https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+
+function update_linux () {
+  pushd linux
+  git fetch --depth 1
+  git reset --hard origin/master
+  popd
+}
+
+function fetch_linux () {
+  git clone --depth=1 $LINUX_URL --branch master --single-branch
+}
+
+function get_or_fetch_linux_kernel () {
+  if [[ -d linux ]]; then
+    update_linux
+  else
+    fetch_linux
+  fi;
+}
+
+function build_kernel_headers () {
+  if [[ -d kernel-headers ]]; then
+    return
+  fi
+
+  pushd linux
+  make LLVM=1 INSTALL_HDR_PATH=../kernel-headers mrproper headers_install -j$(nproc)
+  popd
+}
+
+get_or_fetch_linux_kernel
+build_kernel_headers

From c97a2510eaaaf17ead0a92921913313dc8d484bf Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 09:23:40 -0700
Subject: [PATCH 03/11] move musl code to separate script

---
 bootstrap.sh | 51 +++--------------------------------------------
 musl.sh      | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 48 deletions(-)
 create mode 100755 musl.sh

diff --git a/bootstrap.sh b/bootstrap.sh
index 2a9dd62..c08cc2b 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -1,7 +1,6 @@
 set -eu
 
 LLVM_URL=https://github.com/llvm/llvm-project.git
-MUSL_URL=git://git.musl-libc.org/musl
 
 function update_llvm () {
   pushd llvm-project
@@ -23,7 +22,7 @@ function get_or_fetch_llvm () {
 }
 
 function bootstrap_compiler_rt () {
-  rm -rf sysroot
+  #rm -rf sysroot
   mkdir -p sysroot
   SYSROOT=$(readlink -f sysroot)
   CC=$(which clang)
@@ -57,51 +56,7 @@ function bootstrap_compiler_rt () {
   popd
 }
 
-function update_musl () {
-  pushd musl
-  git fetch --depth 1
-  git reset --hard origin/master
-  popd
-}
-
-function fetch_musl () {
-  git clone --depth=1 $MUSL_URL --branch master --single-branch
-}
-
-function get_or_fetch_musl () {
-  if [[ -d musl ]]; then
-    update_musl
-  else
-    fetch_musl
-  fi;
-}
-
-function build_musl () {
-  BUILTINS=$(readlink -f sysroot/usr/local/lib/linux/libclang_rt.builtins-x86_64.a)
-  CC=$(which clang)
-  SYSROOT=$(readlink -f sysroot)
-  rm -rf musl/build
-  mkdir -p musl/build
-  pushd musl/build
-  LIBCC=$BUILTINS CC=$CC ../configure \
-    --prefix=/usr/local/ \
-    --host=x86_64-unknown-linux-musl \
-    --syslibdir=/usr/local/lib \
-    --disable-static
-
-  make -j$(nproc) AR=llvm-ar RANLIB=llvm-ranlib
-  make DESTDIR=$SYSROOT install-libs install-headers -j$(nproc)
-
-  # TODO: hack
-  pushd $SYSROOT/usr/local/lib
-  ln -sf libc.so ld-musl-x86_64.so.1
-  popd
-  popd
-  ./test_lib.sh
-}
-
-#get_or_fetch_llvm
+get_or_fetch_llvm
 bootstrap_compiler_rt
 ./kernel.sh
-#get_or_fetch_musl
-build_musl
+./musl.sh
diff --git a/musl.sh b/musl.sh
new file mode 100755
index 0000000..3eb9465
--- /dev/null
+++ b/musl.sh
@@ -0,0 +1,56 @@
+set -eu
+
+MUSL_URL=git://git.musl-libc.org/musl
+
+function update_musl () {
+  pushd musl
+  git fetch --depth 1
+  git reset --hard origin/master
+  popd
+}
+
+function fetch_musl () {
+  git clone --depth=1 $MUSL_URL --branch master --single-branch
+}
+
+function get_or_fetch_musl () {
+  if [[ -d musl ]]; then
+    update_musl
+  else
+    fetch_musl
+  fi;
+}
+
+function build_musl () {
+  # TODO: something better than this...like if we updated musl.
+  if [[ -d sysroot/usr/local/include ]]; then
+    if [[ -n "$(find sysroot/usr/local/include -type f | wc -l)" ]]; then
+      return
+    fi;
+  fi;
+
+  BUILTINS=$(readlink -f sysroot/usr/local/lib/linux/libclang_rt.builtins-x86_64.a)
+  CC=$(which clang)
+  SYSROOT=$(readlink -f sysroot)
+  rm -rf musl/build
+  mkdir -p musl/build
+  pushd musl/build
+  LIBCC=$BUILTINS CC=$CC ../configure \
+    --prefix=/usr/local/ \
+    --host=x86_64-unknown-linux-musl \
+    --syslibdir=/usr/local/lib \
+    --disable-static
+
+  make -j$(nproc) AR=llvm-ar RANLIB=llvm-ranlib
+  make DESTDIR=$SYSROOT install-libs install-headers -j$(nproc)
+
+  # TODO: hack
+  pushd $SYSROOT/usr/local/lib
+  ln -sf libc.so ld-musl-x86_64.so.1
+  popd
+  popd
+  ./test_lib.sh
+}
+
+get_or_fetch_musl
+build_musl

From c5c907e0caf41d44333f2df84ff176281a948d75 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 09:40:52 -0700
Subject: [PATCH 04/11] build libunwind

---
 bootstrap.sh | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/bootstrap.sh b/bootstrap.sh
index c08cc2b..55025fb 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -56,7 +56,34 @@ function bootstrap_compiler_rt () {
   popd
 }
 
+function build_libunwind () {
+  SYSROOT=$(readlink -f sysroot)
+  RESOURCE=$(readlink -f sysroot/usr/local)
+  CC=$(which clang)
+  CXX=$(which clang++)
+
+  mkdir -p llvm-project/libunwind/build
+  pushd llvm-project/libunwind/build
+  cmake -D CMAKE_BUILD_TYPE=Release \
+    -D CMAKE_CXX_COMPILER=$CXX \
+    -D CMAKE_CXX_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D CMAKE_C_COMPILER=$CC \
+    -D CMAKE_C_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D CMAKE_SHARED_LINKER_FLAGS=-resource-dir=$RESOURCE \
+    -D LIBUNWIND_ENABLE_STATIC=NO \
+    -D LIBUNWIND_USE_COMPILER_RT=YES \
+    -D LIBUNWIND_INCLUDE_DOCS=NO \
+    -D LLVM_ENABLE_PROJECTS="libunwind" \
+    -D LLVM_TARGETS_TO_BUILD="X86;" \
+    -G Ninja \
+    -S ..
+  ninja libunwind.so
+  DESTDIR=$SYSROOT ninja install
+  popd
+}
+
 get_or_fetch_llvm
 bootstrap_compiler_rt
 ./kernel.sh
 ./musl.sh
+build_libunwind

From f6bcf368b9dac685299cb4ad67494714c98e2390 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 11:37:28 -0700
Subject: [PATCH 05/11] libcxxabi

---
 bootstrap.sh | 67 ++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 60 insertions(+), 7 deletions(-)

diff --git a/bootstrap.sh b/bootstrap.sh
index 55025fb..1de5c44 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -4,8 +4,10 @@ LLVM_URL=https://github.com/llvm/llvm-project.git
 
 function update_llvm () {
   pushd llvm-project
-  git fetch --depth 1
-  git reset --hard origin/main
+  # hack for https://reviews.llvm.org/D97572.
+  git fetch --depth 1 origin 3a6365a439ede4b7c65076bb42b1b7dbf72216b5
+  #git fetch --depth 1
+  git reset --hard FETCH_HEAD
   popd
 }
 
@@ -51,6 +53,7 @@ function bootstrap_compiler_rt () {
     #-D CMAKE_INSTALL_PREFIX=woof \
     #-D COMPILER_RT_INSTALL_PATH=woof \
     #-D COMPILER_RT_INSTALL_LIBRARY_DIR=woof \
+    #-D COMPILER_RT_BUILD_CRT=YES \
   ninja compiler-rt
   DESTDIR=$SYSROOT ninja install
   popd
@@ -82,8 +85,58 @@ function build_libunwind () {
   popd
 }
 
-get_or_fetch_llvm
-bootstrap_compiler_rt
-./kernel.sh
-./musl.sh
-build_libunwind
+function build_libcxxabi () {
+  SYSROOT=$(readlink -f sysroot/)
+  RESOURCE=$(readlink -f sysroot/usr/local)
+  LIBCXX=$(readlink -f llvm-project/libcxx)
+  CC=$(which clang)
+  CXX=$(which clang++)
+
+  # TODO: a hack
+  pushd sysroot/usr/local/lib
+  if [[ ! -e crtbeginS.o ]]; then
+    ln -s linux/clang_rt.crtbegin-x86_64.o crtbeginS.o
+  fi
+  if [[ ! -e crtendS.o ]]; then
+    ln -s linux/clang_rt.crtend-x86_64.o crtendS.o
+  fi
+  popd
+
+  rm -rf llvm-project/libcxxabi/build #
+  mkdir -p llvm-project/libcxxabi/build
+  pushd llvm-project/libcxxabi/build
+  # TODO: link with lld
+  cmake -D CMAKE_BUILD_TYPE=Release \
+    -D CMAKE_CXX_COMPILER_WORKS=YES \
+    -D CMAKE_CXX_COMPILER=$CXX \
+    -D CMAKE_CXX_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D CMAKE_C_COMPILER=$CC \
+    -D CMAKE_C_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D LIBCXXABI_ENABLE_STATIC=NO \
+    -D LIBCXXABI_LIBCXX_INCLUDES=$LIBCXX/include \
+    -D LIBCXXABI_LIBCXX_PATH=$LIBCXX \
+    -D LIBCXXABI_TARGET_TRIPLE=x86_64-unknown-linux-musl \
+    -D LIBCXXABI_USE_COMPILER_RT=YES \
+    -D LIBCXXABI_USE_LLVM_UNWINDER=YES \
+    -D LIBCXXABI_SYSROOT=$RESOURCE \
+    -D LIBCXXABI_SUPPORTS_NOSTDLIBXX_FLAG=NO \
+    -D CMAKE_EXE_LINKER_FLAGS="-rtlib=compiler-rt -resource-dir=$RESOURCE --sysroot=$RESOURCE" \
+    -G Ninja \
+    -S ..
+    #-D CMAKE_SHARED_LINKER_FLAGS=-resource-dir=$RESOURCE \
+    #-D LLVM_ENABLE_PROJECTS="libcxxabi" \
+    #-D LLVM_TARGETS_TO_BUILD="X86;" \
+    # -D CMAKE_CXX_COMPILER_WORKS=YES seems like a hack, but we can't test
+    # what we haven't built yet.
+    #--debug-trycompile \
+  ninja libc++abi.so
+  DESTDIR=$SYSROOT ninja install
+  popd
+}
+
+#get_or_fetch_llvm
+#bootstrap_compiler_rt
+#./kernel.sh
+#./musl.sh
+#build_libunwind
+build_libcxxabi

From 2a4f56269e6d776215d6a76707a29b8946b04b8a Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 13:25:18 -0700
Subject: [PATCH 06/11] license+readme

---
 LICENSE-2.0.txt | 202 ++++++++++++++++++++++++++++++++++++++++++++++++
 README.md       |  29 +++++++
 2 files changed, 231 insertions(+)
 create mode 100644 LICENSE-2.0.txt
 create mode 100644 README.md

diff --git a/LICENSE-2.0.txt b/LICENSE-2.0.txt
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/LICENSE-2.0.txt
@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
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+      designated in writing by the copyright owner as "Not a Contribution."
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+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
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+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
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+      Work and such Derivative Works in Source or Object form.
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+   3. Grant of Patent License. Subject to the terms and conditions of
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+      (except as stated in this section) patent license to make, have made,
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+
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+   6. Trademarks. This License does not grant permission to use the trade
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+   7. Disclaimer of Warranty. Unless required by applicable law or
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+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
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+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
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+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
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+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
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+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e42cace
--- /dev/null
+++ b/README.md
@@ -0,0 +1,29 @@
+A set of (poorly-written) shell scripts to demonstrate building LLVM against
+musl.
+
+This code is for demonstration purposes only; it should be used only as
+reference for cleaner build systems.
+
+An explicit goal is to try to keep the CMAKE variables as explicit in the
+sources as possible.
+
+This work is heavily derived and derived entirely from Saleem Abdulrasool's
+(@compnerd)
+[gist](https://gist.github.com/compnerd/ebbc625a359d1d3e292e1fd2007ecb52).
+
+### License
+```
+Copyright 2021 The ClangBuiltLinux project contributors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+```

From 9d50aa1142c0a3b61d212d659e596e41e4053288 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 14:00:14 -0700
Subject: [PATCH 07/11] document picture of sysroot

---
 README.md | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/README.md b/README.md
index e42cace..aad5132 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,42 @@ This work is heavily derived and derived entirely from Saleem Abdulrasool's
 (@compnerd)
 [gist](https://gist.github.com/compnerd/ebbc625a359d1d3e292e1fd2007ecb52).
 
+### Sysroot
+
+Builds a sysroot that looks like:
+```
+sysroot
+└── usr
+    └── local
+        ├── include
+        │   ├── ...
+        └── lib
+            ├── crt1.o
+            ├── crtbeginS.o -> linux/clang_rt.crtbegin-x86_64.o
+            ├── crtendS.o -> linux/clang_rt.crtend-x86_64.o
+            ├── crti.o
+            ├── crtn.o
+            ├── ld-musl-x86_64.so.1 -> libc.so
+            ├── libc++abi.so -> libc++abi.so.1
+            ├── libc++abi.so.1 -> libc++abi.so.1.0
+            ├── libc++abi.so.1.0
+            ├── libcrypt.a
+            ├── libc.so
+            ├── libdl.a
+            ├── libm.a
+            ├── libpthread.a
+            ├── libresolv.a
+            ├── librt.a
+            ├── libunwind.so -> libunwind.so.1
+            ├── libunwind.so.1 -> libunwind.so.1.0
+            ├── libunwind.so.1.0
+            ├── libutil.a
+            ├── libxnet.a
+            ├── linux
+            ├── rcrt1.o
+            └── Scrt1.o
+```
+
 ### License
 ```
 Copyright 2021 The ClangBuiltLinux project contributors

From 5c95e4806026076ff1cc6a2794a99001734767c5 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 13:56:16 -0700
Subject: [PATCH 08/11] WIP: trying to get libc++ to build

also, I had libc++abi built, but upon wiping my build artifacts and
rerunning fresh, that doesn't build anymore...
---
 .gitignore   |  4 +++-
 bootstrap.sh | 68 +++++++++++++++++++++++++++++++++++++++++++++-------
 kernel.sh    |  6 ++---
 3 files changed, 65 insertions(+), 13 deletions(-)

diff --git a/.gitignore b/.gitignore
index 8e96f8f..6cb4c33 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,8 @@
+# third party sources
+
 linux/
 llvm-project/
 musl/
 
+# build outputs
 sysroot/
-kernel-headers/
diff --git a/bootstrap.sh b/bootstrap.sh
index 1de5c44..950c63e 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -6,13 +6,21 @@ function update_llvm () {
   pushd llvm-project
   # hack for https://reviews.llvm.org/D97572.
   git fetch --depth 1 origin 3a6365a439ede4b7c65076bb42b1b7dbf72216b5
+  #git checkout FETCH_HEAD
   #git fetch --depth 1
   git reset --hard FETCH_HEAD
   popd
 }
 
 function fetch_llvm () {
-  git clone --depth=1 $LLVM_URL --branch main --single-branch
+  #git clone --depth=1 $LLVM_URL --branch main --single-branch
+  mkdir llvm-project
+  pushd llvm-project
+  git init
+  git remote add origin $LLVM_URL
+  git fetch --depth 1 origin 3a6365a439ede4b7c65076bb42b1b7dbf72216b5
+  git checkout FETCH_HEAD
+  popd
 }
 
 function get_or_fetch_llvm () {
@@ -85,6 +93,8 @@ function build_libunwind () {
   popd
 }
 
+# Saleem: c++abi is the libc equivalent for c++: it is the language runtime;
+# libc++ is the C++ standard library
 function build_libcxxabi () {
   SYSROOT=$(readlink -f sysroot/)
   RESOURCE=$(readlink -f sysroot/usr/local)
@@ -102,7 +112,7 @@ function build_libcxxabi () {
   fi
   popd
 
-  rm -rf llvm-project/libcxxabi/build #
+  #rm -rf llvm-project/libcxxabi/build #
   mkdir -p llvm-project/libcxxabi/build
   pushd llvm-project/libcxxabi/build
   # TODO: link with lld
@@ -134,9 +144,51 @@ function build_libcxxabi () {
   popd
 }
 
-#get_or_fetch_llvm
-#bootstrap_compiler_rt
-#./kernel.sh
-#./musl.sh
-#build_libunwind
-build_libcxxabi
+function build_libcxx () {
+  CC=$(which clang)
+  CXX=$(which clang++)
+  SYSROOT=$(readlink -f sysroot/)
+  RESOURCE=$(readlink -f sysroot/usr/local)
+
+  #rm -rf llvm-project/libcxx/build #
+  mkdir -p llvm-project/libcxx/build
+  pushd llvm-project/libcxx/build
+
+  # TODO: link with lld
+  cmake \
+    -D CMAKE_BUILD_TYPE=Release \
+    -D CMAKE_CXX_COMPILER=$CXX \
+    -D CMAKE_CXX_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D CMAKE_CXX_COMPILER_WORKS=YES \
+    -D CMAKE_C_COMPILER=$CC \
+    -D CMAKE_C_COMPILER_TARGET=x86_64-unknown-linux-musl \
+    -D LIBCXX_ENABLE_STATIC=NO \
+    -D LIBCXX_CXX_ABI=libcxxabi \
+    -D LIBCXX_TARGET_TRIPLE=x86_64-unknown-linux-musl \
+    -D LIBCXX_SYSROOT=$SYSROOT/usr/local \
+    -D LIBCXX_HAS_MUSL_LIBC=YES \
+    -D LIBCXX_USE_COMPILER_RT=YES \
+    --debug-trycompile \
+    -D CMAKE_EXE_LINKER_FLAGS="-rtlib=compiler-rt -resource-dir=$RESOURCE --sysroot=$RESOURCE" \
+    -G Ninja \
+    -S ..
+    #-D CMAKE_C_COMPILER_WORKS=YES \
+    #-D LIBCXX_LINK_FLAGS="-stdlib=libc++" \
+    #-D LIBCXX_LINK_FLAGS="-nodefaultlibs -lc -rtlib=compiler-rt" \
+  ninja libc++.so
+
+
+  popd
+}
+
+get_or_fetch_llvm
+bootstrap_compiler_rt
+./kernel.sh
+./musl.sh
+build_libunwind
+#build_libcxxabi
+#TODO: this doesn't work yet
+#build_libcxx
+
+# Fangrui says try:
+# -DLLVM_HOST_TRIPLE= 
diff --git a/kernel.sh b/kernel.sh
index 49c46c4..c3111cf 100755
--- a/kernel.sh
+++ b/kernel.sh
@@ -22,12 +22,10 @@ function get_or_fetch_linux_kernel () {
 }
 
 function build_kernel_headers () {
-  if [[ -d kernel-headers ]]; then
-    return
-  fi
+  SYSROOT=$(readlink -f sysroot)
 
   pushd linux
-  make LLVM=1 INSTALL_HDR_PATH=../kernel-headers mrproper headers_install -j$(nproc)
+  make LLVM=1 INSTALL_HDR_PATH=$SYSROOT/usr/local mrproper headers_install -j$(nproc)
   popd
 }
 

From 6a08c944a60d39621d4cb6de55061318a6f9d8b6 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 14:14:42 -0700
Subject: [PATCH 09/11] remove bad check that was preventing musl headers from
 being installed, breaking the build of libcxxabi.

---
 bootstrap.sh |  2 +-
 musl.sh      | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/bootstrap.sh b/bootstrap.sh
index 950c63e..b2c69ab 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -186,7 +186,7 @@ bootstrap_compiler_rt
 ./kernel.sh
 ./musl.sh
 build_libunwind
-#build_libcxxabi
+build_libcxxabi
 #TODO: this doesn't work yet
 #build_libcxx
 
diff --git a/musl.sh b/musl.sh
index 3eb9465..55f06a9 100755
--- a/musl.sh
+++ b/musl.sh
@@ -23,11 +23,11 @@ function get_or_fetch_musl () {
 
 function build_musl () {
   # TODO: something better than this...like if we updated musl.
-  if [[ -d sysroot/usr/local/include ]]; then
-    if [[ -n "$(find sysroot/usr/local/include -type f | wc -l)" ]]; then
-      return
-    fi;
-  fi;
+  #if [[ -d sysroot/usr/local/include ]]; then
+    #if [[ -n "$(find sysroot/usr/local/include -type f | wc -l)" ]]; then
+      #return
+    #fi;
+  #fi;
 
   BUILTINS=$(readlink -f sysroot/usr/local/lib/linux/libclang_rt.builtins-x86_64.a)
   CC=$(which clang)

From 9c7274159b1d09f885f5916ece93c7402f58deab Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 15:41:19 -0700
Subject: [PATCH 10/11] get libc++ building thanks to @compnerd

---
 README.md    |  5 +++++
 bootstrap.sh | 11 +++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index aad5132..3693a56 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,8 @@ sysroot
             ├── libc++abi.so.1.0
             ├── libcrypt.a
             ├── libc.so
+            ├── libc++.so.1 -> libc++.so.1.0
+            ├── libc++.so.1.0
             ├── libdl.a
             ├── libm.a
             ├── libpthread.a
@@ -43,6 +45,9 @@ sysroot
             ├── libutil.a
             ├── libxnet.a
             ├── linux
+            │   ├── clang_rt.crtbegin-x86_64.o
+            │   ├── clang_rt.crtend-x86_64.o
+            │   └── libclang_rt.builtins-x86_64.a
             ├── rcrt1.o
             └── Scrt1.o
 ```
diff --git a/bootstrap.sh b/bootstrap.sh
index b2c69ab..b43154d 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -168,15 +168,19 @@ function build_libcxx () {
     -D LIBCXX_SYSROOT=$SYSROOT/usr/local \
     -D LIBCXX_HAS_MUSL_LIBC=YES \
     -D LIBCXX_USE_COMPILER_RT=YES \
-    --debug-trycompile \
+    -D LIBCXX_INCLUDE_BENCHMARKS=NO \
     -D CMAKE_EXE_LINKER_FLAGS="-rtlib=compiler-rt -resource-dir=$RESOURCE --sysroot=$RESOURCE" \
+    -D LIBCXX_SUPPORTS_NOSTDLIBXX_FLAG=NO \
     -G Ninja \
     -S ..
+    # TODO: should we add LIBCXX_BUILTINS_LIBRARY="${SYSROOT}/usr/local/lib/linux/libclang_rt.builtins-x86_64.a"
+    # as per @compnerd?
+    #--debug-trycompile \
     #-D CMAKE_C_COMPILER_WORKS=YES \
     #-D LIBCXX_LINK_FLAGS="-stdlib=libc++" \
     #-D LIBCXX_LINK_FLAGS="-nodefaultlibs -lc -rtlib=compiler-rt" \
   ninja libc++.so
-
+  DESTDIR=$SYSROOT ninja install-cxx install-cxx-headers
 
   popd
 }
@@ -187,8 +191,7 @@ bootstrap_compiler_rt
 ./musl.sh
 build_libunwind
 build_libcxxabi
-#TODO: this doesn't work yet
-#build_libcxx
+build_libcxx
 
 # Fangrui says try:
 # -DLLVM_HOST_TRIPLE= 

From 2b697bd6c56f11cb35081377b3db5f6cc7eca927 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 22 Sep 2021 17:48:28 -0700
Subject: [PATCH 11/11] fixup libunwind

---
 bootstrap.sh | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/bootstrap.sh b/bootstrap.sh
index b43154d..d68de85 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -73,6 +73,10 @@ function build_libunwind () {
   CC=$(which clang)
   CXX=$(which clang++)
 
+  # - LIBUNWIND_COMPILE_FLAGS: flags used to compile libunwind
+  # - LIBUNWIND_LINK_FLAGS: flags used to link libunwind
+  # - LIBUNWIND_LIBRARIES: libraries to link libunwind to.
+  rm -rf llvm-project/libunwind/build #
   mkdir -p llvm-project/libunwind/build
   pushd llvm-project/libunwind/build
   cmake -D CMAKE_BUILD_TYPE=Release \
@@ -82,12 +86,24 @@ function build_libunwind () {
     -D CMAKE_C_COMPILER_TARGET=x86_64-unknown-linux-musl \
     -D CMAKE_SHARED_LINKER_FLAGS=-resource-dir=$RESOURCE \
     -D LIBUNWIND_ENABLE_STATIC=NO \
-    -D LIBUNWIND_USE_COMPILER_RT=YES \
     -D LIBUNWIND_INCLUDE_DOCS=NO \
-    -D LLVM_ENABLE_PROJECTS="libunwind" \
+    -D LIBUNWIND_USE_COMPILER_RT=YES \
     -D LLVM_TARGETS_TO_BUILD="X86;" \
+    -D LIBUNWIND_TARGET_TRIPLE=x86_64-unknown-linux-musl \
+    -D LIBUNWIND_SYSROOT=$RESOURCE \
+    -D CMAKE_REQUIRED_FLAGS="-rtlib=compiler-rt -resource-dir=$RESOURCE" \
+    --debug-trycompile \
     -G Ninja \
     -S ..
+    #-D CMAKE_REQUIRED_LINK_OPTIONS="-rtlib=compiler-rt;-resource-dir=$RESOURCE" \
+    #-D CMAKE_EXE_LINKER_FLAGS="-Xlinker --dynamic-linker=$RESOURCE/lib/ld-musl-x86_64.so.1" \
+    #-D LIBUNWIND_COMPILE_FLAGS="-Xlinker --dynamic-linker=$RESOURCE/lib/ld-musl-x86_64.so.1" \
+    #-D LIBUNWIND_LINK_FLAGS="-Xlinker --dynamic-linker=$RESOURCE/lib/ld-musl-x86_64.so.1" \
+    #-D LIBUNWIND_LINK_FLAGS="--sysroot=$RESOURCE" \
+    #-D CMAKE_CXX_COMPILER_WORKS=YES \
+    #-D CMAKE_EXE_LINKER_FLAGS="-nostdlib" \
+    #-D LLVM_ENABLE_PROJECTS="libunwind" \
+    #-D CMAKE_EXE_LINKER_FLAGS="-resource-dir=$RESOURCE --sysroot=$RESOURCE" \
   ninja libunwind.so
   DESTDIR=$SYSROOT ninja install
   popd