Consider adding extra newline after blocks

[jdreaver]

Hello! I'm really excited you all have built this project. It is much nicer to debug LLVM IR issues in my compiler when I can see it printed, versus when I make a mistake and just see a segfault from the C++ LLVM library 😄

I noticed that when I print my LLVM IR using moduleLLVMAssembly, I get wonderful newlines after each block:

; ModuleID = 'amy-module'
source_filename = "<string>"

define i64 @main() {
entry:
  %0 = call i64 @fib(i64 10)
  ret i64 %0
}

define private i64 @fib(i64 %x) {
entry:
  switch i64 %x, label %case.default.0 [
    i64 0, label %case.0.0
    i64 1, label %case.1.0
  ]

case.default.0:                                   ; preds = %entry
  %0 = sub i64 %x, 1
  %1 = call i64 @fib(i64 %0)
  %2 = sub i64 %x, 2
  %3 = call i64 @fib(i64 %2)
  %4 = add i64 %1, %3
  br label %case.end.0

case.0.0:                                         ; preds = %entry
  br label %case.end.0

case.1.0:                                         ; preds = %entry
  br label %case.end.0

case.end.0:                                       ; preds = %case.1.0, %case.0.0, %case.default.0
  %end.0 = phi i64 [ %4, %case.default.0 ], [ 0, %case.0.0 ], [ 1, %case.1.0 ]
  ret i64 %end.0
}

When I use llvm-hs-pretty, those newlines are gone:

; ModuleID = 'amy-module'


define external ccc i64 @main(){
entry:
  %0 = call ccc i64 @fib(i64 10)
  ret i64 %0
}

define private ccc i64 @fib(i64 %x){
entry:
  switch i64 %x, label %case.default.0 [i64 0, label %case.0.0 i64 1, label %case.1.0]
case.default.0:
  %1 = sub i64 %x, 1
  %2 = call ccc i64 @fib(i64 %1)
  %3 = sub i64 %x, 2
  %4 = call ccc i64 @fib(i64 %3)
  %5 = add i64 %2, %4
  br label %case.end.0
case.0.0:
  br label %case.end.0
case.1.0:
  br label %case.end.0
case.end.0:
  %end.0 = phi i64 [%5, %case.default.0], [0, %case.0.0], [1, %case.1.0]
  ret i64 %end.0
}

Do you think those newlines are nice enough to add to llvm-hs-pretty? If not, feel free to close this issue. I'm mostly just popping in with a suggestion.

[sdiehl]

Not opposed I guess. Not sure if there is a canonical formatting for LLVM whitespace.