Avoid closure creation in hot assert

nicolasstucki · nicolasstucki · commit e07da939950c · 2017-10-05T17:19:22.000+02:00
diff --git a/compiler/src/dotty/tools/dotc/core/Flags.scala b/compiler/src/dotty/tools/dotc/core/Flags.scala
@@ -22,7 +22,8 @@ object Flags {
       else if (that.bits == 0) this
       else {
         val tbits = bits & that.bits & KINDFLAGS
-        assert(tbits != 0, s"illegal flagset combination: $this and $that")
+        if (tbits == 0) // Optimised to not create the closure
+          assert(false, s"illegal flagset combination: $this and $that")
         FlagSet(tbits | ((this.bits | that.bits) & ~KINDFLAGS))
       }
 

Original file line number	Diff line number	Diff line change
`@@ -22,7 +22,8 @@ object Flags {`
`22`	`22`	`else if (that.bits == 0) this`
`23`	`23`	`else {`
`24`	`24`	`val tbits = bits & that.bits & KINDFLAGS`
`25`		`- assert(tbits != 0, s"illegal flagset combination: $this and $that")`
	`25`	`+ if (tbits == 0) // Optimised to not create the closure`
	`26`	`+ assert(false, s"illegal flagset combination: $this and $that")`
`26`	`27`	`FlagSet(tbits \| ((this.bits \| that.bits) & ~KINDFLAGS))`
`27`	`28`	`}`
`28`	`29`