cmd/compile: make isfat handle 1-element array, 1-field struct
This will improve liveness analysis slightly, the same logic as
isdirectiface curently does. In:
type T struct {
m map[int]int
}
v := T{}
v.m = make(map[int]int)
T is considered "fat", now it is not. So assigning to v.m is considered
to clobber the entire v.
This is follow up of CL 179057.
Change-Id: Id6b4807b8e8521ef5d8bcb14fedb6dceb9dbf18c
Reviewed-on: https://go-review.googlesource.com/c/go/+/179578
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
diff --git a/src/cmd/compile/internal/gc/plive.go b/src/cmd/compile/internal/gc/plive.go
index 7d3377f..591e2d1 100644
--- a/src/cmd/compile/internal/gc/plive.go
+++ b/src/cmd/compile/internal/gc/plive.go
@@ -1453,9 +1453,21 @@
func isfat(t *types.Type) bool {
if t != nil {
switch t.Etype {
- case TSTRUCT, TARRAY, TSLICE, TSTRING,
+ case TSLICE, TSTRING,
TINTER: // maybe remove later
return true
+ case TARRAY:
+ // Array of 1 element, check if element is fat
+ if t.NumElem() == 1 {
+ return isfat(t.Elem())
+ }
+ return true
+ case TSTRUCT:
+ // Struct with 1 field, check if field is fat
+ if t.NumFields() == 1 {
+ return isfat(t.Field(0).Type)
+ }
+ return true
}
}
diff --git a/test/live.go b/test/live.go
index ec51193..2c8972e 100644
--- a/test/live.go
+++ b/test/live.go
@@ -659,7 +659,7 @@
func good40() {
ret := T40{} // ERROR "stack object ret T40$"
- ret.m = make(map[int]int) // ERROR "live at call to fastrand: .autotmp_[0-9]+ ret$" "stack object .autotmp_[0-9]+ map.hdr\[int\]int$"
+ ret.m = make(map[int]int) // ERROR "live at call to fastrand: .autotmp_[0-9]+$" "stack object .autotmp_[0-9]+ map.hdr\[int\]int$"
t := &ret
printnl() // ERROR "live at call to printnl: ret$"
// Note: ret is live at the printnl because the compiler moves &ret
diff --git a/test/live2.go b/test/live2.go
index cea312f..83a6cb7 100644
--- a/test/live2.go
+++ b/test/live2.go
@@ -27,14 +27,14 @@
}
func bad40() {
- t := newT40() // ERROR "live at call to makemap: ret$" "stack object ret T40$" "stack object .autotmp_[0-9]+ map.hdr\[int\]int$"
+ t := newT40() // ERROR "stack object ret T40$" "stack object .autotmp_[0-9]+ map.hdr\[int\]int$"
printnl() // ERROR "live at call to printnl: ret$"
useT40(t)
}
func good40() {
ret := T40{} // ERROR "stack object ret T40$"
- ret.m = make(map[int]int, 42) // ERROR "live at call to makemap: ret$" "stack object .autotmp_[0-9]+ map.hdr\[int\]int$"
+ ret.m = make(map[int]int, 42) // ERROR "stack object .autotmp_[0-9]+ map.hdr\[int\]int$"
t := &ret
printnl() // ERROR "live at call to printnl: ret$"
useT40(t)
