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3 Commits

Author SHA1 Message Date
Dmitri Shuralyov
b2fd76ab8d test: migrate remaining files to go:build syntax
Most of the test cases in the test directory use the new go:build syntax
already. Convert the rest. In general, try to place the build constraint
line below the test directive comment in more places.

For #41184.
For #60268.

Change-Id: I11c41a0642a8a26dc2eda1406da908645bbc005b
Cq-Include-Trybots: luci.golang.try:gotip-linux-386-longtest,gotip-linux-amd64-longtest,gotip-windows-amd64-longtest
Reviewed-on: https://go-review.googlesource.com/c/go/+/536236
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2023-10-19 23:33:25 +00:00
Keith Randall
332a5981d0 cmd/compile: handle partially overlapping assignments
Normally, when moving Go values of type T from one location to another,
we don't need to worry about partial overlaps. The two Ts must either be
in disjoint (nonoverlapping) memory or in exactly the same location.
There are 2 cases where this isn't true:
 1) Using unsafe you can arrange partial overlaps.
 2) Since Go 1.17, you can use a cast from a slice to a ptr-to-array.
    https://go.dev/ref/spec#Conversions_from_slice_to_array_pointer
    This feature can be used to construct partial overlaps of array types.
      var a [3]int
      p := (*[2]int)(a[:])
      q := (*[2]int)(a[1:])
      *p = *q
We don't care about solving 1. Or at least, we haven't historically
and no one has complained.
For 2, we need to ensure that if there might be partial overlap,
then we can't use OpMove; we must use memmove instead.
(memmove handles partial overlap by copying in the correct
direction. OpMove does not.)

Note that we have to be careful here not to introduce a call when
we're marshaling arguments to a call or unmarshaling results from a call.

Fixes #54467

Change-Id: I1ca6aba8041576849c1d85f1fa33ae61b80a373d
Reviewed-on: https://go-review.googlesource.com/c/go/+/425076
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
2022-08-23 19:56:32 +00:00
Clément Chigot
9fe9853ae5 cmd/compile: fix nilcheck for AIX
This commit adapts compile tool to create correct nilchecks for AIX.

AIX allows to load a nil pointer. Therefore, the default nilcheck
which issues a load must be replaced by a CMP instruction followed by a
store at 0x0 if the value is nil. The store will trigger a SIGSEGV as on
others OS.

The nilcheck algorithm must be adapted to do not remove nilcheck if it's
only a read. Stores are detected with v.Type.IsMemory().

Tests related to nilptr must be adapted to the previous changements.
nilptr.go cannot be used as it's because the AIX address space starts at
1<<32.

Change-Id: I9f5aaf0b7e185d736a9b119c0ed2fe4e5bd1e7af
Reviewed-on: https://go-review.googlesource.com/c/144538
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2018-11-26 14:13:53 +00:00