Implement the segue optimization for LLVM AOT/JIT (#2230)

Segue is an optimization technology which uses x86 segment register to store
the WebAssembly linear memory base address, so as to remove most of the cost
of SFI (Software-based Fault Isolation) base addition and free up a general
purpose register, by this way it may:
- Improve the performance of JIT/AOT
- Reduce the footprint of JIT/AOT, the JIT/AOT code generated is smaller
- Reduce the compilation time of JIT/AOT

This PR uses the x86-64 GS segment register to apply the optimization, currently
it supports linux and linux-sgx platforms on x86-64 target. By default it is disabled,
developer can use the option below to enable it for wamrc and iwasm(with LLVM
JIT enabled):
```bash
wamrc --enable-segue=[<flags>] -o output_file wasm_file
iwasm --enable-segue=[<flags>] wasm_file [args...]
```
`flags` can be:
    i32.load, i64.load, f32.load, f64.load, v128.load,
    i32.store, i64.store, f32.store, f64.store, v128.store
Use comma to separate them, e.g. `--enable-segue=i32.load,i64.store`,
and `--enable-segue` means all flags are added.

Acknowledgement:
Many thanks to Intel Labs, UC San Diego and UT Austin teams for introducing this
technology and the great support and guidance!

Signed-off-by: Wenyong Huang <wenyong.huang@intel.com>
Co-authored-by: Vahldiek-oberwagner, Anjo Lucas <anjo.lucas.vahldiek-oberwagner@intel.com>

tests/benchmarks/libsodium/run_aot.sh

@@ -0,0 +1,92 @@
+#!/bin/bash
+
+# Copyright (C) 2019 Intel Corporation.  All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+libsodium_CASES="aead_aes256gcm2 aead_aes256gcm aead_chacha20poly13052 aead_chacha20poly1305 \
+                 aead_xchacha20poly1305 auth2 auth3 auth5 auth6 auth7 auth box2 box7 box8 \
+                 box_easy2 box_easy box_seal box_seed box chacha20 codecs core1 core2 core3 \
+                 core4 core5 core6 core_ed25519 core_ristretto255 ed25519_convert generichash2 \
+                 generichash3 generichash hash3 hash kdf keygen kx metamorphic misuse \
+                 onetimeauth2 onetimeauth7 onetimeauth pwhash_argon2id pwhash_argon2i \
+                 pwhash_scrypt_ll pwhash_scrypt randombytes scalarmult2 scalarmult5 \
+                 scalarmult6 scalarmult7 scalarmult8 scalarmult_ed25519 scalarmult_ristretto255 \
+                 scalarmult secretbox2 secretbox7 secretbox8 secretbox_easy2 secretbox_easy \
+                 secretbox secretstream shorthash sign siphashx24 sodium_core sodium_utils2 \
+                 sodium_utils stream2 stream3 stream4 stream verify1 xchacha20"
+
+PLATFORM=$(uname -s | tr A-Z a-z)
+
+readonly OUT_DIR=$PWD/libsodium/zig-out/bin
+readonly REPORT=$PWD/report.txt
+readonly IWASM_CMD=$PWD/../../../product-mini/platforms/${PLATFORM}/build/iwasm
+readonly TIME=/usr/bin/time
+
+BENCH_NAME_MAX_LEN=20
+
+rm -f $REPORT
+touch $REPORT
+
+function print_bench_name()
+{
+    name=$1
+    echo -en "$name" >> $REPORT
+    name_len=${#name}
+    if [ $name_len -lt $BENCH_NAME_MAX_LEN ]
+    then
+        spaces=$(( $BENCH_NAME_MAX_LEN - $name_len ))
+        for i in $(eval echo "{1..$spaces}"); do echo -n " " >> $REPORT; done
+    fi
+}
+
+# run benchmarks
+cd $OUT_DIR
+
+if [[ ${PLATFORM} == "linux" ]]; then
+    echo -en "\t\t\t\t\t\tnative\tiwasm-aot\tiwasm-aot-segue\n" >> $REPORT
+else
+    echo -en "\t\t\t\t\t\tnative\tiwasm-aot\n" >> $REPORT
+fi
+
+for t in $libsodium_CASES
+do
+    print_bench_name $t
+
+    echo "run $t with native..."
+    echo -en "\t" >> $REPORT
+    if [[ $t != "sodium_utils2" ]]; then
+        ./${t} | awk '{printf "%-10.2f", $0/1000000.0}' >> $REPORT
+    else
+        # sodium_utils2 doesn't print the result,
+        # use time command to get result instead
+        $TIME -f "real-%e-time" ./${t} 2>&1 | grep "real-.*-time" |
+            awk -F '-' '{printf "%-10.2f", $2}' >> $REPORT
+    fi
+
+    echo "run $t with iwasm aot..."
+    echo -en "\t  \t" >> $REPORT
+    if [[ $t != "sodium_utils2" ]]; then
+        $IWASM_CMD ${t}.aot | awk '{printf "%-10.2f", $0/1000000.0}' >> $REPORT
+    else
+        # sodium_utils2 doesn't print the result,
+        # use time command to get result instead
+        $TIME -f "real-%e-time" $IWASM_CMD ${t}.aot 2>&1 | grep "real-.*-time" |
+            awk -F '-' '{printf "%-10.2f", $2}' >> $REPORT
+    fi
+
+    if [[ ${PLATFORM} == "linux" ]]; then
+        echo "run $t with iwasm aot segue..."
+        echo -en "\t  \t" >> $REPORT
+        if [[ $t != "sodium_utils2" ]]; then
+            $IWASM_CMD ${t}_segue.aot | awk '{printf "%.2f", $0/1000000.0}' >> $REPORT
+        else
+            # sodium_utils2 doesn't print the result,
+            # use time command to get result instead
+            $TIME -f "real-%e-time" $IWASM_CMD ${t}_segue.aot 2>&1 | grep "real-.*-time" |
+                awk -F '-' '{printf "%.2f", $2}' >> $REPORT
+        fi
+    fi
+
+    echo -en "\n" >> $REPORT
+done
+