Extract Asm Syclkernel Jit

Extract ASM from JIT-Compiled SYCL Kernels

Same compilation stack as AOT (SYCL → LLVM IR → SPIR-V → IGC → zebin), but execution happens at first kernel launch. The zebin only exists transiently in memory — you MUST re-run with IGC_ShaderDumpEnable=1 to capture it to disk.

How this fits the compilation stack

Build time:
  SYCL source → LLVM IR → SPIR-V
                              ↓
                    embedded in binary (no native code yet)

First launch (runtime):
  SPIR-V → IGC (JIT) → zebin (in memory only!)
                              ↓
            IGC_ShaderDumpEnable=1 → dumps to disk ← this is what we capture
                              ↓
                         .asm file (with // file:line comments from IGC)

Why IGC_ShaderDumpEnable=1 is required: Unlike AOT where the zebin is statically extractable from the binary, JIT zebin only exists in GPU driver memory. Without the dump flag, it's never written to disk.

Bonus: JIT dump produces .asm files with inline // file:line comments (IGC's EmitPass annotates them directly).

When to use

• Kernel is _ZTS… AND one of:
  • Binary has NO __CLANG_OFFLOAD_BUNDLE (pure JIT build)
  • Binary has AOT bundle but target does not match current device (e.g. built for PVC, running on BMG — runtime falls back to JIT via SPIR-V)
• Common cases:
  • torch-xpu-ops built with TORCH_XPU_ARCH_LIST=none
  • Standalone DPC++ without -fsycl-targets=spir64_gen
  • Device not in the AOT target list (e.g. TORCH_XPU_ARCH_LIST=pvc on BMG)

When NOT to use

• Binary has AOT code matching current device → use extract-asm-syclkernel-aot
• Kernel is oneDNN ngen → use extract-asm-onednn (different stack)
• Kernel is Triton → use extract-asm-triton

Steps

Prerequisite: The router (extract-xpu-kernel-asm) has already confirmed that the JIT path is active for the current device. This skill assumes IGC will be invoked at runtime.

1. Pin the actually-launched kernel.

   Use unitrace (preferred) or SYCL_UR_TRACE (fallback):

   unitrace -d <repro_cmd>
   # Or fallback:
   SYCL_UR_TRACE=-1 <repro_cmd> 2>&1 | grep -oP 'pKernelName = 0x[0-9a-f]+ \(\K[^)]+' | sort -u
   

   Pick the hot kernel name (<KERNEL>).

2. Re-run with IGC dump (cold cache).

   OUT="<workdir>/$(basename "$BIN")_$(date +%Y%m%d_%H%M%S)"
   mkdir -p "$OUT/igc"
   
   NEO_CACHE_PERSISTENT=0 \
   IGC_ShaderDumpEnable=1 \
   IGC_DumpToCustomDir="$OUT/igc" \ \
     <repro_cmd> 2>&1 | tee "$OUT/run.log"
   
   ls "$OUT/igc"/*.asm | wc -l
   

3. Match kernel name to .asm file.

   MATCH=$(grep -l "$KERNEL" "$OUT/igc"/OCL_asm*_simd*_entry_*.asm | head -1)
   test -n "$MATCH" || { echo "no asm matches $KERNEL"; exit 1; }
   echo "asm-file: $MATCH"