runtime: eliminate most uses of mheap_.arena_*

This replaces all uses of the mheap_.arena_* fields outside of
mallocinit and sysAlloc. These fields fundamentally assume a
contiguous heap between two bounds, so eliminating these is necessary
for a sparse heap.

Many of these are replaced with checks for non-nil spans at the test
address (which in turn checks for a non-nil entry in the heap arena
array). Some of them are just for debugging and somewhat meaningless
with a sparse heap, so those we just delete.

Updates #10460.

Change-Id: I8345b95ffc610aed694f08f74633b3c63506a41f
Reviewed-on: https://go-review.googlesource.com/85886
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>

1 files changed, 0 insertions, 12 deletions

diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
index 5e109f5906..0027bc9c05 100644
--- a/src/runtime/mbitmap.go
+++ b/src/runtime/mbitmap.go
@@ -308,9 +308,6 @@ func (m markBits) clearMarked() {
 
 // markBitsForSpan returns the markBits for the span base address base.
 func markBitsForSpan(base uintptr) (mbits markBits) {
-	if base < mheap_.arena_start || base >= mheap_.arena_used {
-		throw("markBitsForSpan: base out of range")
-	}
 	mbits = markBitsForAddr(base)
 	if mbits.mask != 1 {
 		throw("markBitsForSpan: unaligned start")
@@ -352,15 +349,6 @@ func heapBitsForAddr(addr uintptr) heapBits {
 	return heapBits{bitp, uint32(off & 3), uint32(arena), last}
 }
 
-// heapBitsForSpan returns the heapBits for the span base address base.
-func heapBitsForSpan(base uintptr) (hbits heapBits) {
-	if base < mheap_.arena_start || base >= mheap_.arena_used {
-		print("runtime: base ", hex(base), " not in range [", hex(mheap_.arena_start), ",", hex(mheap_.arena_used), ")\n")
-		throw("heapBitsForSpan: base out of range")
-	}
-	return heapBitsForAddr(base)
-}
-
 // findObject returns the base address for the heap object containing
 // the address p, the object's span, and the index of the object in s.
 // If p does not point into a heap object, it returns base == 0.