runtime: remove checkgc code from hashmap

Currently hashmap is riddled with code that attempts to force a GC on
the next allocation if checkgc is set. This no longer works as
originally intended with the concurrent collector, and is apparently
no longer used anyway.

Remove checkgc.

Change-Id: Ia6c17c405fa8821dc2e6af28d506c1133ab1ca0c
Reviewed-on: https://go-review.googlesource.com/8355
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/runtime/hashmap.go b/src/runtime/hashmap.go
index aaaef483811acf5ae7a6e022d38a9470af63248e..9ca33992bb4dc2d7d4df07a000ee229e66e95685 100644 (file)
--- a/src/runtime/hashmap.go
+++ b/src/runtime/hashmap.go
@@ -96,9 +96,6 @@ const (
 
        // sentinel bucket ID for iterator checks
        noCheck = 1<<(8*ptrSize) - 1
-
-       // trigger a garbage collection at every alloc called from this code
-       checkgc = false
 )
 
 // A header for a Go map.
@@ -246,16 +243,10 @@ func makemap(t *maptype, hint int64, h *hmap, bucket unsafe.Pointer) *hmap {
        // If hint is large zeroing this memory could take a while.
        buckets := bucket
        if B != 0 {
-               if checkgc {
-                       memstats.next_gc = memstats.heap_alloc
-               }
                buckets = newarray(t.bucket, uintptr(1)<<B)
        }
 
        // initialize Hmap
-       if checkgc {
-               memstats.next_gc = memstats.heap_alloc
-       }
        if h == nil {
                h = (*hmap)(newobject(t.hmap))
        }
@@ -430,9 +421,6 @@ func mapassign1(t *maptype, h *hmap, key unsafe.Pointer, val unsafe.Pointer) {
        hash := alg.hash(key, uintptr(h.hash0))
 
        if h.buckets == nil {
-               if checkgc {
-                       memstats.next_gc = memstats.heap_alloc
-               }
                h.buckets = newarray(t.bucket, 1)
        }
 
@@ -493,9 +481,6 @@ again:
 
        if inserti == nil {
                // all current buckets are full, allocate a new one.
-               if checkgc {
-                       memstats.next_gc = memstats.heap_alloc
-               }
                newb := (*bmap)(newobject(t.bucket))
                h.setoverflow(t, b, newb)
                inserti = &newb.tophash[0]
@@ -505,17 +490,11 @@ again:
 
        // store new key/value at insert position
        if t.indirectkey {
-               if checkgc {
-                       memstats.next_gc = memstats.heap_alloc
-               }
                kmem := newobject(t.key)
                *(*unsafe.Pointer)(insertk) = kmem
                insertk = kmem
        }
        if t.indirectvalue {
-               if checkgc {
-                       memstats.next_gc = memstats.heap_alloc
-               }
                vmem := newobject(t.elem)
                *(*unsafe.Pointer)(insertv) = vmem
                insertv = vmem
@@ -776,9 +755,6 @@ func hashGrow(t *maptype, h *hmap) {
                throw("evacuation not done in time")
        }
        oldbuckets := h.buckets
-       if checkgc {
-               memstats.next_gc = memstats.heap_alloc
-       }
        newbuckets := newarray(t.bucket, uintptr(1)<<(h.B+1))
        flags := h.flags &^ (iterator | oldIterator)
        if h.flags&iterator != 0 {
@@ -879,9 +855,6 @@ func evacuate(t *maptype, h *hmap, oldbucket uintptr) {
                                if (hash & newbit) == 0 {
                                        b.tophash[i] = evacuatedX
                                        if xi == bucketCnt {
-                                               if checkgc {
-                                                       memstats.next_gc = memstats.heap_alloc
-                                               }
                                                newx := (*bmap)(newobject(t.bucket))
                                                h.setoverflow(t, x, newx)
                                                x = newx
@@ -906,9 +879,6 @@ func evacuate(t *maptype, h *hmap, oldbucket uintptr) {
                                } else {
                                        b.tophash[i] = evacuatedY
                                        if yi == bucketCnt {
-                                               if checkgc {
-                                                       memstats.next_gc = memstats.heap_alloc
-                                               }
                                                newy := (*bmap)(newobject(t.bucket))
                                                h.setoverflow(t, y, newy)
                                                y = newy