provide build script for LLVM

Signed-off-by: xermicus <cyrill@parity.io>

.gitignore

@@ -6,3 +6,5 @@
 /*.yul
 /*.ll
 /*.s
+/llvm-project
+/llvm18.0

README.md

@@ -28,7 +28,7 @@ The project is in a very early PoC phase. Don't yet expect the produced code to
 - [ ] Debug information
 - [ ] Look for and implement further optimizations
 - [ ] Differential testing against EVM
-- [ ] Switch to LLVM 18 which has `RV{32,64}E` targets upstream
+- [x] Switch to LLVM 18 which has `RV{32,64}E` targets upstream
 - [ ] Minimize scope of "stdlib"
 - [ ] Document differences from EVM
 - [ ] Audit for bugs and correctness

build-llvm.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+INSTALL_DIR="${PWD}/llvm18.0"
+mkdir -p $INSTALL_DIR
+
+
+# Clone LLVM (any revision after commit bd32aaa is supposed to work)
+if [ ! -d "llvm-project" ]; then
+  git clone --depth 1 --branch main https://github.com/llvm/llvm-project.git
+fi
+
+
+# Build LLVM, clang
+cd llvm-project
+
+mkdir -p build
+cd build
+cmake -G Ninja -DLLVM_ENABLE_ASSERTIONS=On \
+  -DLLVM_ENABLE_TERMINFO=Off \
+  -DLLVM_ENABLE_LIBXML2=Off \
+  -DLLVM_ENABLE_ZLIB=Off \
+  -DLLVM_ENABLE_PROJECTS='clang;lld' \
+  -DLLVM_TARGETS_TO_BUILD='RISCV' \
+  -DLLVM_ENABLE_ZSTD=Off \
+  -DCMAKE_BUILD_TYPE=MinSizeRel \
+  -DCMAKE_INSTALL_PREFIX=$INSTALL_DIR \
+	../llvm
+
+ninja
+ninja install
+
+
+# Build compiler builtins
+cd ../compiler-rt
+mkdir -p build
+cd build
+
+CFLAGS="--target=riscv32 -march=rv32em -mabi=ilp32e -nostdlib -nodefaultlibs -mcpu=generic-rv32"
+cmake -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$INSTALL_DIR \
+  -DCOMPILER_RT_BUILD_BUILTINS=ON \
+  -DCOMPILER_RT_BUILD_LIBFUZZER=OFF \
+  -DCOMPILER_RT_BUILD_MEMPROF=OFF \
+  -DCOMPILER_RT_BUILD_PROFILE=OFF \
+  -DCOMPILER_RT_BUILD_SANITIZERS=OFF \
+  -DCOMPILER_RT_BUILD_XRAY=OFF \
+  -DCMAKE_C_COMPILER=$INSTALL_DIR/bin/clang \
+  -DCMAKE_C_COMPILER_TARGET="riscv32" \
+  -DCMAKE_ASM_COMPILER_TARGET="riscv32" \
+  -DCMAKE_AR=$INSTALL_DIR/bin/llvm-ar \
+  -DCMAKE_NM=$INSTALL_DIR/bin/llvm-nm \
+  -DCMAKE_RANLIB=$INSTALL_DIR/bin/llvm-ranlib \
+  -DCOMPILER_RT_BAREMETAL_BUILD=ON \
+  -DLLVM_CONFIG_PATH=$INSTALL_DIR/bin/llvm-config \
+  -DCMAKE_C_FLAGS="$CFLAGS" \
+  -DCMAKE_ASM_FLAGS="$CFLAGS" \
+  -DCOMPILER_RT_TEST_COMPILER=$INSTALL_DIR/bin/clang \
+  -DCMAKE_CXX_FLAGS="$CFLAGS" \
+  -DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON \
+  -DCMAKE_SYSTEM_NAME=Linux \
+  ..
+
+ninja
+ninja install
+
+
+echo ""
+echo "success"
+echo "add this directory to your PATH: ${INSTALL_DIR}/bin/"