From 96f3fb7244680fbb04549914384ced7afe433daf Mon Sep 17 00:00:00 2001 From: Matthew Dempsky Date: Mon, 23 Nov 2020 04:28:25 -0800 Subject: [PATCH] [dev.regabi] go/constant: avoid heap allocations in match When type switching from interface{} to T, and then returning the T as interface{} again, it's better to return the original interface{} value. This avoids needing to heap allocate the T for non-pointer-shaped types (i.e., int64Val, complexVal, stringVal). Change-Id: I25c83b3f9ec9bd2ffeec5a65279b68f4fcef8a19 Reviewed-on: https://go-review.googlesource.com/c/go/+/272647 Run-TryBot: Matthew Dempsky TryBot-Result: Go Bot Trust: Matthew Dempsky Reviewed-by: Robert Griesemer --- src/go/constant/value.go | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) diff --git a/src/go/constant/value.go b/src/go/constant/value.go index 59606dc479..4a89ef3b94 100644 --- a/src/go/constant/value.go +++ b/src/go/constant/value.go @@ -1023,52 +1023,55 @@ func match(x, y Value) (_, _ Value) { } // ord(x) <= ord(y) - switch x := x.(type) { + // Prefer to return the original x and y arguments when possible, + // to avoid unnecessary heap allocations. + + switch x1 := x.(type) { case boolVal, *stringVal, complexVal: return x, y case int64Val: - switch y := y.(type) { + switch y.(type) { case int64Val: return x, y case intVal: - return i64toi(x), y + return i64toi(x1), y case ratVal: - return i64tor(x), y + return i64tor(x1), y case floatVal: - return i64tof(x), y + return i64tof(x1), y case complexVal: - return vtoc(x), y + return vtoc(x1), y } case intVal: - switch y := y.(type) { + switch y.(type) { case intVal: return x, y case ratVal: - return itor(x), y + return itor(x1), y case floatVal: - return itof(x), y + return itof(x1), y case complexVal: - return vtoc(x), y + return vtoc(x1), y } case ratVal: - switch y := y.(type) { + switch y.(type) { case ratVal: return x, y case floatVal: - return rtof(x), y + return rtof(x1), y case complexVal: - return vtoc(x), y + return vtoc(x1), y } case floatVal: - switch y := y.(type) { + switch y.(type) { case floatVal: return x, y case complexVal: - return vtoc(x), y + return vtoc(x1), y } } -- 2.48.1