Compilation is working again

Include dependency on riscv toolchain
Include small llvm patch

Author: lrettig

build.sh

@@ -4,6 +4,15 @@ set -euo pipefail
 
 source config.sh
 
+# Rust requires a custom target file to exist for our custom target as part of the bootstrap build,
+# but it doesn't actually look at the contents.
+touch /tmp/riscv32em-athena-zkvm-elf.json
+
 # Will create component archives (dists) ./rust/build/dist
 cd rust
-CARGO_TARGET_RISCV32EM_ATHENA_ZKVM_ELF_RUSTFLAGS="-Cpasses=loweratomic" ./x build --stage 2
+#RUSTFLAGS="-C link-arg=-L$HOME/compiler_rt_build_riscv32em-athena-zkvm-elf/lib/baremetal" \
+#LIBRARY_PATH="$HOME/compiler_rt_build_riscv32em-athena-zkvm-elf/lib/baremetal" \
+RUST_TARGET_PATH="/tmp" \
+CARGO_TARGET_RISCV32EM_ATHENA_ZKVM_ELF_RUSTFLAGS="-Cpasses=loweratomic" \
+CFLAGS_riscv32em_athena_zkvm_elf="-ffunction-sections -fdata-sections -fPIC -march=rv32em -mabi=ilp32e" \
+./x build --stage 2

patch.sh

@@ -5,3 +5,6 @@ set -euo pipefail
 cd rust
 patch -p1 < ../patches/rust.patch
 cp ../patches/config.toml ./
+
+cd src/llvm-project
+patch -p1 < ../../../patches/llvm.patch

patches/config.ci.toml

@@ -7,6 +7,10 @@ tools = ["cargo", "cargo-clippy", "clippy", "rustfmt"]
 configure-args = []
 cargo-native-static = true
 
+[target.riscv32em-athena-zkvm-elf]
+cc = "riscv32-unknown-elf-gcc"
+cxx = "riscv32-unknown-elf-g++"
+
 [rust]
 lld = true
 llvm-tools = true

patches/config.toml

@@ -6,6 +6,10 @@ extended = true
 tools = ["cargo", "cargo-clippy", "clippy", "rustfmt"]
 configure-args = []
 
+[target.riscv32em-athena-zkvm-elf]
+cc = "riscv32-unknown-elf-gcc"
+cxx = "riscv32-unknown-elf-g++"
+
 [rust]
 lld = true
 llvm-tools = true

patches/llvm.patch

@@ -0,0 +1,17 @@
+diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
+index 28ded8766..b51ebe8ea 100644
+--- a/compiler-rt/lib/builtins/CMakeLists.txt
++++ b/compiler-rt/lib/builtins/CMakeLists.txt
+@@ -849,9 +849,9 @@ else ()
+ 
+       # For RISCV32, we must force enable int128 for compiling long
+       # double routines.
+-      if(COMPILER_RT_ENABLE_SOFTWARE_INT128 OR "${arch}" STREQUAL "riscv32")
+-        list(APPEND BUILTIN_CFLAGS_${arch} -fforce-enable-int128)
+-      endif()
++      #if(COMPILER_RT_ENABLE_SOFTWARE_INT128 OR "${arch}" STREQUAL "riscv32")
++      #  list(APPEND BUILTIN_CFLAGS_${arch} -fforce-enable-int128)
++      #endif()
+ 
+       add_compiler_rt_runtime(clang_rt.builtins
+                               STATIC