0コード.ml

let rec fact_ i acc = if i = 0 then acc else fact_ (i-1) (i+acc) in
let rec fact i = fact_ i 0 in
println_int (fact x)

1最適化前.ll

; ModuleID = 'foo.ml'
source_filename = "foo.ml"
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-darwin15.6.0"

@x = external global i64

declare void @println_int(i64) #0

; Function Attrs: inlinehint nounwind ssp uwtable
define i64 @"fact$t4"(i64 %"i$t5") #1 {
entry:
  %0 = call i64 @"fact_$t1"(i64 %"i$t5", i64 0)
  ret i64 %0
}

; Function Attrs: inlinehint nounwind ssp uwtable
define i64 @"fact_$t1"(i64 %"i$t2", i64 %"acc$t3") #1 {
entry:
  %eql = icmp eq i64 %"i$t2", 0
  br i1 %eql, label %if.then, label %if.else

if.then:                                          ; preds = %entry
  br label %if.end

if.else:                                          ; preds = %entry
  %sub = sub i64 %"i$t2", 1
  %add = add i64 %"i$t2", %"acc$t3"
  %0 = call i64 @"fact_$t1"(i64 %sub, i64 %add)
  br label %if.end

if.end:                                           ; preds = %if.else, %if.then
  %if.merge = phi i64 [ %"acc$t3", %if.then ], [ %0, %if.else ]
  ret i64 %if.merge
}

; Function Attrs: ssp uwtable
define i32 @main() #2 {
entry:
  %x = load i64, i64* @x
  %0 = call i64 @"fact$t4"(i64 %x)
  call void @println_int(i64 %0)
  ret i32 0
}

attributes #0 = { "disable-tail-calls"="false" }
attributes #1 = { inlinehint nounwind ssp uwtable "disable-tail-calls"="false" }
attributes #2 = { ssp uwtable "disable-tail-calls"="false" }

2最適化後.ll

; ModuleID = 'foo.ml'
source_filename = "foo.ml"
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-darwin15.6.0"

@x = external local_unnamed_addr global i64

declare void @println_int(i64) local_unnamed_addr #0

; Function Attrs: inlinehint norecurse nounwind readnone ssp uwtable
define i64 @"fact$t4"(i64 %"i$t5") local_unnamed_addr #1 {
entry:
  %eql1.i = icmp eq i64 %"i$t5", 0
  br i1 %eql1.i, label %"fact_$t1.exit", label %if.else.preheader.i

if.else.preheader.i:                              ; preds = %entry
  %0 = add i64 %"i$t5", -1
  %1 = mul i64 %0, %0
  %2 = zext i64 %0 to i65
  %3 = add i64 %"i$t5", -2
  %4 = zext i64 %3 to i65
  %5 = mul i65 %2, %4
  %6 = lshr i65 %5, 1
  %7 = trunc i65 %6 to i64
  %8 = add i64 %1, %"i$t5"
  %9 = sub i64 %8, %7
  br label %"fact_$t1.exit"

"fact_$t1.exit":                                  ; preds = %entry, %if.else.preheader.i
  %"acc$t3.tr.lcssa.i" = phi i64 [ 0, %entry ], [ %9, %if.else.preheader.i ]
  ret i64 %"acc$t3.tr.lcssa.i"
}

; Function Attrs: inlinehint nounwind readnone ssp uwtable
define i64 @"fact_$t1"(i64 %"i$t2", i64 %"acc$t3") local_unnamed_addr #2 {
entry:
  %eql1 = icmp eq i64 %"i$t2", 0
  br i1 %eql1, label %if.end, label %if.else.preheader

if.else.preheader:                                ; preds = %entry
  %0 = add i64 %"i$t2", -1
  %1 = mul i64 %0, %0
  %2 = zext i64 %0 to i65
  %3 = add i64 %"i$t2", -2
  %4 = zext i64 %3 to i65
  %5 = mul i65 %2, %4
  %6 = lshr i65 %5, 1
  %7 = trunc i65 %6 to i64
  %8 = add i64 %"acc$t3", %"i$t2"
  %9 = add i64 %8, %1
  %10 = sub i64 %9, %7
  br label %if.end

if.end:                                           ; preds = %if.else.preheader, %entry
  %"acc$t3.tr.lcssa" = phi i64 [ %"acc$t3", %entry ], [ %10, %if.else.preheader ]
  ret i64 %"acc$t3.tr.lcssa"
}

; Function Attrs: ssp uwtable
define i32 @main() local_unnamed_addr #3 {
entry:
  %x = load i64, i64* @x, align 8
  %eql1.i.i = icmp eq i64 %x, 0
  br i1 %eql1.i.i, label %"fact$t4.exit", label %if.else.preheader.i.i

if.else.preheader.i.i:                            ; preds = %entry
  %0 = add i64 %x, -1
  %1 = mul i64 %0, %0
  %2 = zext i64 %0 to i65
  %3 = add i64 %x, -2
  %4 = zext i64 %3 to i65
  %5 = mul i65 %2, %4
  %6 = lshr i65 %5, 1
  %7 = trunc i65 %6 to i64
  %8 = add i64 %1, %x
  %9 = sub i64 %8, %7
  br label %"fact$t4.exit"

"fact$t4.exit":                                   ; preds = %entry, %if.else.preheader.i.i
  %"acc$t3.tr.lcssa.i.i" = phi i64 [ 0, %entry ], [ %9, %if.else.preheader.i.i ]
  tail call void @println_int(i64 %"acc$t3.tr.lcssa.i.i")
  ret i32 0
}

attributes #0 = { "disable-tail-calls"="false" }
attributes #1 = { inlinehint norecurse nounwind readnone ssp uwtable "disable-tail-calls"="false" }
attributes #2 = { inlinehint nounwind readnone ssp uwtable "disable-tail-calls"="false" }
attributes #3 = { ssp uwtable "disable-tail-calls"="false" }