CL 476717 adopted the memory management mechanism on Plan 9 to
manage Wasm's linear memory. But the Plan 9 code uses global
variable bloc and blocMax to keep track of the runtime's and the
OS's sense of break, whereas the Wasm sbrk function doesn't use
those global variables, and directly goes to grow the linear
memory instead. This causes that if there is any unused portion at
the end of the linear memory, the runtime doesn't use it. This CL
fixes it, adopts the same mechanism as the Plan 9 code.
In particular, the runtime is not aware of any unused initial
memory at startup. Therefore, (most of) the extra initial memory
set by the linker are not actually used. This CL fixes this as
well.
For #69018.
Change-Id: I2ea6a138310627eda5f19a1c76b1e1327362e5f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/621635 Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>