How to use it? about decomp HOT 1 CLOSED

# Install Clang and LLVM
pacman -Sy clang llvm

# Install GraphViz dot
pacman -Sy graphviz

go get github.com/decomp/decomp/cmd/...
go get github.com/decomp/exp/cmd/dot2png
# TODO: uncomment once https://github.com/jackspirou/grind/pull/6 is merged.
#go get github.com/jackspirou/grind
# Below is a workaround until jackspirou/grind#6 is merged.
git clone -b go-importer https://github.com/mewpull/grind /tmp/grind; cd /tmp/grind; go install; cd -

go get github.com/mewkiz/cmd/sar
go get golang.org/x/tools/cmd/goimports

$ make
# * Step 0
#    - Convert original C source code to LLVM IR.
#
#    - input:  foo.c
#    - output: foo.ll
clang -S -emit-llvm -o foo.ll foo.c
opt -S --mem2reg -o foo.ll foo.ll
# * Step 1
#    - Produce control flow graphs for each function of the LLVM IR.
#
#    - input:  foo.ll
#    - output: foo_graphs/main.dot
ll2dot -f foo.ll
ll2dot: parsing file "foo.ll".
ll2dot: parsing function "@main".
ll2dot: creating file "foo_graphs/main.dot".
# * Step 2
#    - Perform control flow analysis on the control flow graphs to recover
#      the high-level control flow primitives of each function.
#
#    - input:  foo_graphs/main.dot
#    - output: foo_graphs/main.json
#    - output (optional): foo_graphs/main_NNNN{a,b}.dot (when the debug flag -steps is used)
cd foo_graphs; restructure -indent -steps -o main.json main.dot
# (optional) Convert DOT control flow graphs to PNG images.
dot2png foo_graphs/*.dot
2019/10/31 12:45:12 Creating: "foo_graphs/main_0001a.png"
2019/10/31 12:45:12 Creating: "foo_graphs/main_0001b.png"
2019/10/31 12:45:12 Creating: "foo_graphs/main_0002a.png"
2019/10/31 12:45:12 Creating: "foo_graphs/main_0002b.png"
2019/10/31 12:45:12 Creating: "foo_graphs/main_0003a.png"
2019/10/31 12:45:12 Creating: "foo_graphs/main_0003b.png"
2019/10/31 12:45:12 Creating: "foo_graphs/main_0004a.png"
2019/10/31 12:45:12 Creating: "foo_graphs/main_0004b.png"
2019/10/31 12:45:12 Creating: "foo_graphs/main.png"
# * Step 3
#    - Decompile the LLVM IR assembly to unpolished Go source code, using
#      control flow recovery information produced by restructure.
#
#    - input:  foo.ll
#    - input:  foo_graphs/main.json
#    - output: foo_pre.go
ll2go foo.ll > foo_pre.go
ll2go: parsing file "foo.ll".
ll2go: decompiling function "@main".
# * Step 4
#    - Post-process the decompiled Go source code.
#
#    - input:  foo.go (actually a copy of foo_pre.go, since rewrite happens inplace)
#    - output: foo.go
cp foo_pre.go foo.go
go-post foo.go
foo.go: fixed unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved unresolved mem2var cmain varnames
# Force run "localid" post-processing rule (disabled by default).
go-post -force localid foo.go
foo.go: fixed localid assignbinop
# Move variable declarations closer to their use.
grind foo.go
0
c_main: cannot inline gotos without type information
main: cannot inline gotos without type information
EDIT: foo.go
@@ -3,16 +3,11 @@ package main
 import "os"
 
 func c_main(_0 int32, _1 **int8) int32 {
-	var v_3 int32
-	var v_4 int32
-	var v_5 **int8
-	var v_6 int32
-	var v_7 int32
-	v_3 = 0
-	v_4 = _0
-	v_5 = _1
-	v_7 = 0
-	v_6 = 0
+	v_3 := int32(0)
+	v_4 := _0
+	v_5 := _1
+	v_7 := int32(0)
+	v_6 := int32(0)
 
 	for v_6 <
 		10 {

1
c_main: cannot inline gotos without type information
main: cannot inline gotos without type information
# The rewrites of Grind enabled further rewrite rules of go-post.
#
# Note: use -diff to see the change of an given go-post rewrite; e.g.
#
#    go-post -diff -r forloop foo.go
go-post -r forloop foo.go
foo.go: fixed forloop
go-post -r unusedvar foo.go
foo.go: fixed unusedvar
# Use sar to remove useless newlines.
sar -i "\n\n" "\n" foo.go
sar -i '([*<])\n' '$1 ' foo.go
# Use goimports to format the output Go source code.
#
#    - input:  foo.go
#    - output: foo.go
goimports -w foo.go
# Add whitespace between top-level function declarations.
sar -i "}\nfunc" "}\n\nfunc" foo.go

# Result produced by original C source code:
$ clang -o foo foo.c
$ ./foo ; echo $?
108

# Result produced by decompiled Go source code:
$ go run foo.go
exit status 108