Add auxiliary scripts for benchmarking

- build_benchmarks.sh: Automated build script for ISPC benchmarks for
  specified targets between two ISPC revisions
- create_benchmark_comparison_table.py: Python tool to parse benchmark
  JSON results and generate comparison tables in ASCII/CSV/Markdown
- run_all_benchmark_comparisons.sh: Batch runner that executes benchmark
  comparisons for all target pairs in the current directory
- run_and_compare_benchmarks.sh: Core comparison script that runs
  benchmarks and uses Google Benchmark's compare.py tool to analyze
  performance differences

Author: nurmukhametov

scripts/build_benchmarks.sh

@@ -0,0 +1,111 @@
+#!/bin/bash
+# Copyright (c) 2025, Intel Corporation
+# SPDX-License-Identifier: BSD-3-Clause
+
+set -euo pipefail
+
+DEFAULT_TARGETS="avx512skx-x4 avx512skx-x8 avx512skx-x16 avx512skx-x32 avx512skx-x64 avx512icl-x4 avx512icl-x8 avx512icl-x16 avx512icl-x32 avx512icl-x64"
+
+show_usage() {
+    cat <<EOF
+Usage: $0 [BASE_SHA] [PEAK_SHA] [BUILD_TARGETS]
+
+Build ISPC benchmarks for performance comparison between two commits.
+
+ARGUMENTS:
+  BASE_SHA        Base commit SHA for comparison (default: HEAD^)
+  PEAK_SHA        Peak commit SHA for comparison (default: HEAD)
+  BUILD_TARGETS   Space-separated list of ISPC targets (default: all AVX-512 targets)
+
+DEFAULT TARGETS:
+  $DEFAULT_TARGETS
+
+EXAMPLES:
+  $0                                  # Compare HEAD^ vs HEAD with default targets
+  $0 abc123 def456                    # Compare specific commits with default targets
+  $0 HEAD~5 HEAD "avx2-i32x8 avx512skx-x16"  # Compare commits with custom targets
+
+The script will:
+1. Check out PEAK_SHA and build benchmarks for each target
+2. Check out BASE_SHA and build benchmarks for each target
+3. Create separate build directories for each target/version combination
+
+Build directories will be named: {target}-peak and {target}-base
+EOF
+}
+
+if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
+    show_usage
+    exit 0
+fi
+
+BASE_SHA="${1:-HEAD^}"
+PEAK_SHA="${2:-HEAD}"
+BUILD_TARGETS="${3:-$DEFAULT_TARGETS}"
+
+echo "Building benchmarks for ISPC with base SHA: $BASE_SHA and peak SHA: $PEAK_SHA"
+echo "Targets: $BUILD_TARGETS"
+
+# Convert space-separated targets to array
+IFS=' ' read -ra TARGET_ARRAY <<< "$BUILD_TARGETS"
+
+# Build peak version for each target
+echo "Checking out peak SHA: $PEAK_SHA"
+git checkout "$PEAK_SHA"
+
+for target in "${TARGET_ARRAY[@]}"; do
+    echo "Building peak version for target: $target"
+    BUILD_DIR="${target}-peak"
+    LOG_FILE="${target}-peak.build.log"
+
+    rm -rf "$BUILD_DIR"
+
+    cmake ../ -G Ninja \
+        -DISPC_SLIM_BINARY=ON \
+        -DISPC_INCLUDE_EXAMPLES=OFF \
+        -DISPC_INCLUDE_RT=OFF \
+        -DISPC_INCLUDE_UTILS=OFF \
+        -DISPC_INCLUDE_TESTS=OFF \
+        -DISPC_INCLUDE_BENCHMARKS=ON \
+        -DARM_ENABLED=OFF \
+        -B "$BUILD_DIR" \
+        -DBENCHMARKS_ISPC_FLAGS="-O3 -woff" \
+        -DBENCHMARKS_ISPC_TARGETS="$target"
+
+    echo ""
+    echo "Build phase:"
+    echo "============"
+
+    cmake --build "$BUILD_DIR"
+done
+
+# Build base version for each target
+echo "Checking out base SHA: $BASE_SHA"
+git checkout "$BASE_SHA"
+
+for target in "${TARGET_ARRAY[@]}"; do
+    echo "Building base version for target: $target"
+    BUILD_DIR="${target}-base"
+
+    rm -rf "$BUILD_DIR"
+
+    cmake ../ -G Ninja \
+        -DISPC_SLIM_BINARY=ON \
+        -DISPC_INCLUDE_EXAMPLES=OFF \
+        -DISPC_INCLUDE_RT=OFF \
+        -DISPC_INCLUDE_UTILS=OFF \
+        -DISPC_INCLUDE_TESTS=OFF \
+        -DISPC_INCLUDE_BENCHMARKS=ON \
+        -DARM_ENABLED=OFF \
+        -B "$BUILD_DIR" \
+        -DBENCHMARKS_ISPC_FLAGS="-O3 -woff" \
+        -DBENCHMARKS_ISPC_TARGETS="$target"
+
+    echo ""
+    echo "Build phase:"
+    echo "============"
+
+    cmake --build "$BUILD_DIR"
+done
+
+echo "Build completed for all targets: $BUILD_TARGETS"