Improved benchmarking for WAMR, LLVM 20

Author: psilva261

README.md

@@ -85,6 +85,7 @@ ziskemu -e build/bin/println.zkvm.elf
 ```
 
 #### QEMU RISC-V
+
 ```bash
 ./platform/riscv-qemu/scripts/c2riscv-qemu.sh \
     build/c-packages/println \
@@ -96,14 +97,18 @@ qemu-system-riscv64 -machine virt -bios none \
 ```
 
 #### QEMU RISC-V WAMR
+
+Include OpenSBI BIOS (`-bios default` instead of `-bios none`) such that a shutdown function is present for improved benchmarking.
+
 ```bash
 ./platform/riscv-wamr-qemu/scripts/wasm2wamr-qemu.sh \
     examples/build-wasm/go/fibonacci.wasm \
     build/bin/fibonacci.wamr.elf
 
 # Run in QEMU
-qemu-system-riscv64 -machine virt -m 1024M -bios none \
-    -kernel build/bin/fibonacci.wamr.elf -nographic
+./docker/docker-shell.sh qemu-system-riscv64 -machine virt -m 1024M \
+    -kernel build/bin/fibonacci.wamr.elf -nographic -icount shift=0 \
+    -plugin /libinsn.so
 ```
 
 ## Examples

docker/Dockerfile

@@ -56,9 +56,16 @@ RUN git clone https://github.com/turbolent/w2c2.git /opt/w2c2 && \
 
 RUN apt update && apt install -y git build-essential ninja-build pkg-config libglib2.0-dev libpixman-1-dev
 
+# Include patch for insn.c because otherwise this error appears due to unknown
+# instructions:
+#
+# ERROR:../tests/tcg/plugins/insn.c:97:vcpu_init: assertion failed: (count > 0)
+#
+# https://lists.gnu.org/archive/html/qemu-discuss/2025-08/msg00001.html
 RUN git clone https://git.qemu.org/git/qemu.git && \
     cd qemu && \
-    ./configure --target-list=riscv64-linux-user --enable-plugins && \
+    sed -i 's/g_assert(count > 0)/g_assert(count >= 0)/g' tests/tcg/plugins/insn.c && \
+    ./configure --target-list=riscv64-linux-user,riscv64-softmmu --enable-plugins && \
     make -j4 && \
     make install && \
     cp build/tests/tcg/plugins/libinsn.so /libinsn.so && \
@@ -74,20 +81,16 @@ RUN git clone https://git.qemu.org/git/qemu.git && \
 # https://github.com/bytecodealliance/wasm-micro-runtime/issues/418
 # https://github.com/bytecodealliance/wasm-micro-runtime/issues/531
 #
-# Additionally use LLVM 19. Profiling wamrc when compiling a large wasm
-# file like stateful.wasm shows that AttemptToFoldSymbolOffsetDifference
+# Additionally use LLVM 20. Profiling wamrc when compiling a large wasm
+# file like stateless.wasm shows that AttemptToFoldSymbolOffsetDifference
 # consumes most of the compile time. LLVM 19 contains a fix for this
-# though
+# though. Also large code model is in principle supported for RISC-V
+# since version 20.
 #
 # https://github.com/llvm/llvm-project/issues/81440
-RUN git clone https://github.com/bytecodealliance/wasm-micro-runtime.git /opt/wamr
-COPY platform/riscv-wamr-qemu/wamr-platform/ /opt/wamr/core/shared/platform/zkvm/
-RUN cd /opt/wamr && \
-    sed -i "s/find_package(Threads REQUIRED)/find_package(Threads)/g" CMakeLists.txt && \
-    sed -i "/SymbolMap target_sym_map/a REG_SYM(__floatundisf)," core/iwasm/aot/arch/aot_reloc_riscv.c && \
-    sed -i "/SymbolMap target_sym_map/a REG_SYM(__floatdisf)," core/iwasm/aot/arch/aot_reloc_riscv.c && \
-    sed -i "/SymbolMap target_sym_map/a REG_SYM(__ltsf2)," core/iwasm/aot/arch/aot_reloc_riscv.c && \
-    sed -i "s/18\.x/19.x/g" build-scripts/build_llvm.py && \
+RUN git clone https://github.com/psilva261/wasm-micro-runtime-zkvm.git /opt/wamr/ && \
+    cd /opt/wamr && \
+    git checkout zkvm && \
     cmake . \
         -DWAMR_BUILD_PLATFORM=zkvm \
         -DWAMR_BUILD_TARGET=AOT \

platform/riscv-qemu/scripts/c2riscv-qemu.sh

@@ -69,7 +69,7 @@ PREFIX=/opt/riscv-newlib/bin/riscv64-unknown-elf-
 
 # Compiler flags (using -O0 for faster compilation of large generated files)
 CFLAGS=(
-    -march=rv64ima
+    -march=rv64ima_zicsr
     -mabi=lp64
     -mcmodel=medany
     -specs=nosys.specs

platform/riscv-wamr-qemu/main.c

@@ -6,6 +6,12 @@
 extern const char wasmModuleBuffer[];
 extern int wasmModuleBuffer_length;
 
+static inline unsigned long rdinstret(void) {
+    unsigned long v;
+    asm volatile ("csrr %0, instret" : "=r"(v));
+    return v;
+}
+
 int main(void) {
     int argc = 0;
     char *argv[0];
@@ -17,6 +23,10 @@ int main(void) {
     wasm_function_inst_t func;
     wasm_exec_env_t exec_env;
     uint32 size, stack_size = 16*1024*1024;
+    unsigned long instrs_start, instrs_init, instrs_load, instrs_inst,
+                  instrs_exec, instrs_unload, instrs_end;
+
+    instrs_start = rdinstret();
 
     wasm_runtime_set_log_level(WASM_LOG_LEVEL_VERBOSE);
 
@@ -25,28 +35,40 @@ int main(void) {
         printf("runtime init failed\n");
         exit(1);
     }
+    instrs_init = rdinstret();
 
     /* parse the WASM file from buffer and create a WASM module */
     module = wasm_runtime_load(wasmModuleBuffer, wasmModuleBuffer_length, error_buf, sizeof(error_buf));
     if (module == 0) {
         printf("runtime load module failed: %s\n", error_buf);
         exit(1);
     }
+    instrs_load = rdinstret();
 
     /* create an instance of the WASM module (WASM linear memory is ready) */
     module_inst = wasm_runtime_instantiate(module, stack_size, 0, error_buf, sizeof(error_buf));
     if (module_inst == 0) {
         printf("wasm_runtime_instantiate failed as module_inst=%p: %s\n", module_inst, error_buf);
         exit(1);
     }
+    instrs_inst = rdinstret();
 
     if (!wasm_application_execute_main(module_inst, argc, argv)) {
         printf("error executing main\n");
         printf("exception: %s\n", wasm_runtime_get_exception(module_inst));
     }
+    instrs_exec = rdinstret();
 
     printf("wasm_runtime_unload...\n");
     wasm_runtime_unload(module);
+    instrs_end = instrs_unload = rdinstret();
+
+    printf("instructions runtime init:        %lu\n", instrs_init-instrs_start);
+    printf("instructions runtime load:        %lu\n", instrs_load-instrs_init);
+    printf("instructions runtime instantiate: %lu\n", instrs_inst-instrs_load);
+    printf("instructions runtime exec:        %lu\n", instrs_exec-instrs_inst);
+    printf("instructions runtime unload:      %lu\n", instrs_unload-instrs_exec);
+    printf("instructions in total:            %lu\n", instrs_end-instrs_start);
 
     return 0;
 }

platform/riscv-wamr-qemu/scripts/wasm2wamr-qemu.sh

@@ -28,7 +28,8 @@ if [ $# -lt 2 ]; then
     echo "  $0 build/.c-packages/println build/bin/println.riscv.elf"
     echo ""
     echo "To run in QEMU:"
-    echo "  qemu-system-riscv64 -machine virt -bios none \\"
+    echo "  ./docker/docker-shell.sh qemu-system-riscv64 -machine virt \\"
+    echo "    -m 1024M -icount shift=0 -plugin /libinsn.so \\"
     echo "    -kernel build/bin/println.riscv.elf -nographic \\"
     echo "    -semihosting-config enable=on,target=native"
     echo ""
@@ -113,7 +114,7 @@ PREFIX=/opt/riscv-newlib/bin/riscv64-unknown-elf-
 
 # Compiler flags (using -O0 for faster compilation of large generated files)
 CFLAGS=(
-    -march=rv64ima
+    -march=rv64ima_zicsr
     -mabi=lp64
     -mcmodel=medany
     -specs=nosys.specs
@@ -185,8 +186,9 @@ if [ $? -eq 0 ] && [ -f "$OUTPUT" ]; then
     echo "Size: $SIZE"
     echo ""
     echo "To run in QEMU:"
-    echo "  qemu-system-riscv64 -machine virt -m 1024M \\"
-    echo "     -bios none -kernel $OUTPUT -nographic \\"
+    echo "  ./docker/docker-shell.sh qemu-system-riscv64 -machine virt \\"
+    echo "    -m 1024M -icount shift=0 -plugin /libinsn.so \\"
+    echo "    -kernel $OUTPUT -nographic \\"
     echo "    -semihosting-config enable=on,target=native"
     echo ""
 else

platform/riscv-wamr-qemu/startup.S

@@ -4,7 +4,7 @@
 _start:
     la sp, _stack_top
 
-    # Clear BSS section - using symbols defined in our linker script
+    /* Clear BSS section - using symbols defined in our linker script */
     la t0, _bss_start
     la t1, _bss_end
 clear_bss:
@@ -14,8 +14,14 @@ clear_bss:
     j clear_bss
 bss_done:
 
-    # Jump to C code
+    /* Call main */
     call main
 
-    # In case main returns
-1:  j 1b
+    /* https://github.com/xypron/riscv_test_payload (MIT-licensed) */
+    li a7, 0x53525354   # SBI extension: SRST (System Reset)
+    li a6, 0            # Function: system reset
+    li a0, 0            # Reset type: shutdown
+    li a1, 0            # Reset reason: no reason
+    ecall               # Perform system shutdown
+end:
+    j end

platform/riscv-wamr-qemu/syscalls.c

@@ -70,6 +70,6 @@ void* _sbrk(int incr) {
 }
 
 // Required stubs
-void _exit(int code) { while (1); }
+void _exit(int code) {}
 int _kill(int pid, int sig) { return -1; }
 int _getpid(void) { return 1; }

platform/riscv-wamr-qemu/virt.ld

@@ -6,13 +6,13 @@ ENTRY(_start)
 
 /* QEMU virt machine memory map */
 MEMORY {
-    ram (wxa) : ORIGIN = 0x80000000, LENGTH = 1024M
+    ram (wxa) : ORIGIN = 0x80200000, LENGTH = 1024M
 }
 
 SECTIONS
 {
     /* Start of RAM */
-    . = 0x80000000;
+    . = 0x80200000;
 
     /* Code section */
     .text : {