#!/bin/sh

set -e 

msg() { 
    printf '%s\n' "$*"; 
}

if [ $# -ne 2 ]; then
    msg "Usage: compare_v_to_c_performance COMMIT_BEFORE COMMIT_AFTER"
    exit 1
fi

depend_on() { 
    type "$1" >/dev/null 2>&1 || {
        printf 'ERR: missing tool "%s"\n' "$1" >&2; exit 1;
    } 
}

depend_on sh
depend_on cp
depend_on rm
depend_on wc
depend_on head
depend_on cc
depend_on strip
depend_on git
depend_on upx
depend_on make
depend_on hyperfine

######################################################################
## NB: cc should be a working, recent, sane C99 compiler 
##     cc is used by the Makefile to bootstrap v (both gcc/clang work)
##
## If you are a C/V developer in a unix environment, you most probably 
## already have the above installed, with the possible exception of:
## https://github.com/sharkdp/hyperfine
##
## Installing them is out of scope of this tool.
######################################################################

COMMIT_B="$1"
COMMIT_A="$2"

CWD="$(pwd)"
WORKDIR="/tmp"

B="$WORKDIR/v_at_$COMMIT_B"
A="$WORKDIR/v_at_$COMMIT_A"

prepare_v() {
    msg 
    msg "Cloning current v source to $1 ..."
    git clone --quiet "$CWD" "$1"
    
    cd "$1"
    git checkout --quiet "$2"
    
    msg "Making v and vprod compilers in $1"
    make > /dev/null
    ./v -o v compiler 
    ./v -prod -o vprod compiler
    cp v     v_stripped 
    cp vprod vprod_stripped 
    strip *_stripped
    cp v_stripped      v_stripped_upxed
    cp vprod_stripped  vprod_stripped_upxed
    upx -qqq --lzma v_stripped_upxed 
    upx -qqq --lzma vprod_stripped_upxed
    wc -c "$1/v" "$1/v_stripped" "$1/v_stripped_upxed" "$1/vprod" "$1/vprod_stripped" "$1/vprod_stripped_upxed" | head -n -1
    VVERSION="$($1/v --version)"
    GVERSION="$(git rev-parse --short  --verify HEAD)"
    msg "V version is: $VVERSION , local source commit: $GVERSION"
}

compare_v_performance() {
    CMD="$1"
    msg "---------------------------------------------------------------------------------"
    msg "Compare '$CMD'"
    hyperfine --warmup=3 "cd '$B/' && $CMD "  "cd '$A/' && $CMD "
    msg
}

##############################################################################
# Cleanup artifacts from previous runs of this tool:
cd "$WORKDIR"
rm -rf "$A/" "$B/"
##############################################################################

msg "Comparing v compiler performance of commit $COMMIT_B (before) vs commit $COMMIT_A (after) ..."
prepare_v "$B" "$COMMIT_B"
prepare_v "$A" "$COMMIT_A"

cd "$WORKDIR"
compare_v_performance "./v     -o x.c compiler"
compare_v_performance "./vprod -o x.c compiler"
compare_v_performance "./vprod -o x   compiler"