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test(aot): add x18 register reservation test for macOS ARM64
Add a standalone test to verify that the +reserve-x18 LLVM flag is correctly applied when compiling AOT for macOS ARM64. On macOS ARM64, x18 is reserved by Apple for TLS (Thread Local Storage). Without the +reserve-x18 flag, LLVM may generate code that uses x18, causing random SIGSEGV crashes (~80% crash rate in testing). The test: - Creates a WASM module with 24 local variables to stress register allocation - Compiles to AOT with -O3 optimization (which would use x18 without the fix) - Runs 1000 iterations to verify no crashes occur - Only runs on macOS ARM64 (skipped on other platforms) Test results: - Without fix: 82/100 crash rate - With fix: 0/100 crash rate (1000 iterations verified)
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‎.github/workflows/compilation_on_macos.yml‎

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cmake ..
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cmake --build . --config Release --parallel 4
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./import-func-callback
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- name: Test x18 register reservation (macOS ARM64 only)
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if: matrix.os == 'macos-15'
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run: |
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cd product-mini/platforms/darwin
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mkdir -p build && cd build
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cmake .. -DWAMR_BUILD_AOT=1
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cmake --build . --config Release --parallel 4
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cd ../../../../tests/standalone/test-aot-x18-reserve
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./run.sh --aot

‎tests/standalone/test-aot-x18-reserve/run.sh‎

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#!/bin/bash
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#
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# Copyright (C) 2019 Intel Corporation. All rights reserved.
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# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#
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# Test for x18 register reservation on macOS ARM64 (aarch64).
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#
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# On macOS ARM64, x18 is reserved by Apple for TLS (Thread Local Storage).
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# Without the +reserve-x18 LLVM flag, the AOT compiler may generate code
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# that uses x18, causing random SIGSEGV crashes when run on macOS.
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#
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# This test compiles a WASM module that stresses register allocation
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# (forcing x18 usage without the fix) and runs it 1000 times to verify
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# no crashes occur.
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#
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SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
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WAMR_DIR="${SCRIPT_DIR}/../../.."
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# Detect platform
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UNAME_S=$(uname -s)
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UNAME_M=$(uname -m)
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# Only run this test on macOS ARM64
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if [[ "${UNAME_S}" != "Darwin" ]] || [[ "${UNAME_M}" != "arm64" ]]; then
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echo "Skipping x18 reserve test: only applicable on macOS ARM64"
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echo "Current platform: ${UNAME_S} ${UNAME_M}"
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exit 0
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fi
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# Determine iwasm path based on platform
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if [[ "${UNAME_S}" == "Darwin" ]]; then
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IWASM_CMD="${WAMR_DIR}/product-mini/platforms/darwin/build/iwasm"
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else
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IWASM_CMD="${WAMR_DIR}/product-mini/platforms/linux/build/iwasm"
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fi
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WAMRC_CMD="${WAMR_DIR}/wamr-compiler/build/wamrc"
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# Check if required binaries exist
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if [[ ! -x "${IWASM_CMD}" ]]; then
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echo "Error: iwasm not found at ${IWASM_CMD}"
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echo "Please build iwasm first"
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exit 1
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fi
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if [[ ! -x "${WAMRC_CMD}" ]]; then
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echo "Error: wamrc not found at ${WAMRC_CMD}"
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echo "Please build wamrc first"
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exit 1
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fi
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cd "${SCRIPT_DIR}"
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# Find wat2wasm (check CI path first, then system PATH)
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if [[ -x "/opt/wabt/bin/wat2wasm" ]]; then
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WAT2WASM="/opt/wabt/bin/wat2wasm"
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elif command -v wat2wasm &> /dev/null; then
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WAT2WASM="wat2wasm"
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else
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echo "Error: wat2wasm not found"
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echo "Please install wabt tools"
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exit 1
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fi
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# Compile WAT to WASM if needed
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if [[ ! -f stress_registers.wasm ]] || [[ stress_registers.wat -nt stress_registers.wasm ]]; then
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echo "Compiling stress_registers.wat to WASM..."
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if ! ${WAT2WASM} stress_registers.wat -o stress_registers.wasm; then
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echo "Error: Failed to compile WAT to WASM"
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exit 1
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fi
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fi
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if [[ $1 != "--aot" ]]; then
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echo "============> run stress_registers.wasm (interpreter mode)"
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echo "Running 100 iterations in interpreter mode..."
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for i in $(seq 1 100); do
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if ! ${IWASM_CMD} stress_registers.wasm 2>&1; then
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echo "FAILED: Crash at iteration $i"
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exit 1
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fi
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done
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echo "PASSED: 100 iterations completed without crash"
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else
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echo "============> compile stress_registers.wasm to AOT"
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# Compile to AOT - the fix should add +reserve-x18 automatically on macOS ARM64
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if ! ${WAMRC_CMD} --opt-level=3 -o stress_registers.aot stress_registers.wasm; then
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echo "Error: Failed to compile WASM to AOT"
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exit 1
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fi
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echo "============> run stress_registers.aot"
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echo "Running 1000 iterations to verify x18 is properly reserved..."
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echo "(Without the fix, this would crash ~80% of the time)"
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failed=0
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for i in $(seq 1 1000); do
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if ! ${IWASM_CMD} stress_registers.aot 2>&1 > /dev/null; then
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echo "FAILED: Crash at iteration $i"
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failed=1
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break
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fi
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# Progress indicator every 100 iterations
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if [[ $((i % 100)) -eq 0 ]]; then
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echo " Progress: $i/1000 iterations completed"
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fi
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done
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if [[ ${failed} -eq 0 ]]; then
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echo "PASSED: 1000 iterations completed without crash"
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echo "The +reserve-x18 fix is working correctly"
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exit 0
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else
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echo "FAILED: x18 register corruption detected"
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echo "The +reserve-x18 fix may not be applied correctly"
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exit 1
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fi
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fi

‎tests/standalone/test-aot-x18-reserve/stress_registers.wat‎

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;; Copyright (C) 2019 Intel Corporation. All rights reserved.
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;; SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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;; Test module that uses many local variables to stress register allocation.
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;; On ARM64, this will force LLVM to use x18 register if +reserve-x18 is not set.
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;; x18 is reserved by Apple on macOS for TLS, so using it causes crashes.
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(module
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(memory (export "memory") 1)
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(func $stress_registers (export "stress_registers") (param $input i64) (result i64)
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(local $a i64) (local $b i64) (local $c i64) (local $d i64)
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(local $e i64) (local $f i64) (local $g i64) (local $h i64)
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(local $i i64) (local $j i64) (local $k i64) (local $l i64)
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(local $m i64) (local $n i64) (local $o i64) (local $p i64)
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(local $q i64) (local $r i64) (local $s i64) (local $t i64)
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(local $u i64) (local $v i64) (local $w i64) (local $x i64)
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;; Initialize all locals with different values based on input
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(local.set $a (i64.add (local.get $input) (i64.const 1)))
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(local.set $b (i64.mul (local.get $a) (i64.const 2)))
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(local.set $c (i64.add (local.get $b) (i64.const 3)))
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(local.set $d (i64.mul (local.get $c) (i64.const 4)))
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(local.set $e (i64.add (local.get $d) (i64.const 5)))
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(local.set $f (i64.mul (local.get $e) (i64.const 6)))
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(local.set $g (i64.add (local.get $f) (i64.const 7)))
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(local.set $h (i64.mul (local.get $g) (i64.const 8)))
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(local.set $i (i64.add (local.get $h) (i64.const 9)))
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(local.set $j (i64.mul (local.get $i) (i64.const 10)))
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(local.set $k (i64.add (local.get $j) (i64.const 11)))
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(local.set $l (i64.mul (local.get $k) (i64.const 12)))
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(local.set $m (i64.add (local.get $l) (i64.const 13)))
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(local.set $n (i64.mul (local.get $m) (i64.const 14)))
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(local.set $o (i64.add (local.get $n) (i64.const 15)))
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(local.set $p (i64.mul (local.get $o) (i64.const 16)))
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(local.set $q (i64.add (local.get $p) (i64.const 17)))
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(local.set $r (i64.mul (local.get $q) (i64.const 18)))
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(local.set $s (i64.add (local.get $r) (i64.const 19)))
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(local.set $t (i64.mul (local.get $s) (i64.const 20)))
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(local.set $u (i64.add (local.get $t) (i64.const 21)))
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(local.set $v (i64.mul (local.get $u) (i64.const 22)))
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(local.set $w (i64.add (local.get $v) (i64.const 23)))
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(local.set $x (i64.mul (local.get $w) (i64.const 24)))
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;; Now use all of them together to prevent optimization
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(local.get $a)
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(local.get $b))
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(local.get $c))
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(local.get $d))
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(local.get $e))
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(local.get $f))
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(local.get $g))
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(local.get $h))
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(local.get $i))
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(local.get $j))
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(local.get $k))
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(local.get $l))
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(i64.add
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(local.get $m)
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(local.get $n))
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(local.get $o))
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(local.get $p))
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(local.get $q))
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(local.get $r))
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(local.get $s))
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(local.get $t))
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(local.get $u))
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(local.get $v))
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(local.get $w))
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(local.get $x))))
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(func $_start (export "_start")
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(drop (call $stress_registers (i64.const 42)))
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)
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)

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