This was just storage for a linked list.
Change-Id: I850e8db1e1f5e72410f5c904be9409179b56a94a
Reviewed-on: https://go-review.googlesource.com/23484
Reviewed-by: David Chase <drchase@google.com>
As in the elimination of PHEAP|PPARAM in CL 23393,
this is something the front end can trivially take care of
and then not bother the back ends with.
It also eliminates some suspect (and only lightly exercised)
code paths in the back ends.
I don't have a smoking gun for this one but it seems
more clearly correct.
Change-Id: I3b3f5e669b3b81d091ff1e2fb13226a6f14c69d5
Reviewed-on: https://go-review.googlesource.com/23431
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
The liveness computation of parameters generally was never
correct, but forcing all parameters to be live throughout the
function covered up that problem. The new SSA back end is
too clever: even though it currently keeps the parameter values live
throughout the function, it may find optimizations that mean
the current values are not written back to the original parameter
stack slots immediately or ever (for example if a parameter is set
to nil, SSA constant propagation may replace all later uses of the
parameter with a constant nil, eliminating the need to write the nil
value back to the stack slot), so the liveness code must now
track the actual operations on the stack slots, exposing these
problems.
One small problem in the handling of arguments is that nodarg
can return ONAME PPARAM nodes with adjusted offsets, so that
there are actually multiple *Node pointers for the same parameter
in the instruction stream. This might be possible to correct, but
not in this CL. For now, we fix this by using n.Orig instead of n
when considering PPARAM and PPARAMOUT nodes.
The major problem in the handling of arguments is general
confusion in the liveness code about the meaning of PPARAM|PHEAP
and PPARAMOUT|PHEAP nodes, especially as contrasted with PAUTO|PHEAP.
The difference between these two is that when a local variable "moves"
to the heap, it's really just allocated there to start with; in contrast,
when an argument moves to the heap, the actual data has to be copied
there from the stack at the beginning of the function, and when a
result "moves" to the heap the value in the heap has to be copied
back to the stack when the function returns
This general confusion is also present in the SSA back end.
The PHEAP bit worked decently when I first introduced it 7 years ago (!)
in 391425ae. The back end did nothing sophisticated, and in particular
there was no analysis at all: no escape analysis, no liveness analysis,
and certainly no SSA back end. But the complications caused in the
various downstream consumers suggest that this should be a detail
kept mainly in the front end.
This CL therefore eliminates both the PHEAP bit and even the idea of
"heap variables" from the back ends.
First, it replaces the PPARAM|PHEAP, PPARAMOUT|PHEAP, and PAUTO|PHEAP
variable classes with the single PAUTOHEAP, a pseudo-class indicating
a variable maintained on the heap and available by indirecting a
local variable kept on the stack (a plain PAUTO).
Second, walkexpr replaces all references to PAUTOHEAP variables
with indirections of the corresponding PAUTO variable.
The back ends and the liveness code now just see plain indirected
variables. This may actually produce better code, but the real goal
here is to eliminate these little-used and somewhat suspect code
paths in the back end analyses.
The OPARAM node type goes away too.
A followup CL will do the same to PPARAMREF. I'm not sure that
the back ends (SSA in particular) are handling those right either,
and with the framework established in this CL that change is trivial
and the result clearly more correct.
Fixes#15747.
Change-Id: I2770b1ce3cbc93981bfc7166be66a9da12013d74
Reviewed-on: https://go-review.googlesource.com/23393
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Introduce a KeepAlive op which makes sure that its argument is kept
live until the KeepAlive. Use KeepAlive to mark pointer input
arguments as live after each function call and at each return.
We do this change only for pointer arguments. Those are the
critical ones to handle because they might have finalizers.
Doing compound arguments (slices, structs, ...) is more complicated
because we would need to track field liveness individually (we do
that for auto variables now, but inputs requires extra trickery).
Turn off the automatic marking of args as live. That way, when args
are explicitly nulled, plive will know that the original argument is
dead.
The KeepAlive op will be the eventual implementation of
runtime.KeepAlive.
Fixes#15277
Change-Id: I5f223e65d99c9f8342c03fbb1512c4d363e903e5
Reviewed-on: https://go-review.googlesource.com/22365
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
They are guaranteed to be non-nil, no point in inserting
nil checks for them.
Fixes#15390
Change-Id: I3b9a0f2319affc2139dcc446d0a56c6785ae5a86
Reviewed-on: https://go-review.googlesource.com/22291
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
We already keep the entire pragma bitset in n.Func.Pragma, so there's
no need to track Nointerface separately.
Passes toolstash -cmp.
Change-Id: Ic027ece477fcf63b0c1df128a08b89ef0f34fd58
Reviewed-on: https://go-review.googlesource.com/21381
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
When building make.bash, calling Nodes.Set(s) where len(s) == 0 occurs
4738678 times vs 1465415 calls where len(s) > 0; i.e., it is over 3x
more common to set Nodes.slice to nil rather than to s.
Make a copy of slice (header) and take address of that copy instead
to avoid allocating the argument slice on the heap always even when
not needed.
Saves 4738678 slice header allocations and slice header value copies.
Change-Id: I88e8e919ea9868ceb2df46173d187af4109bd947
Reviewed-on: https://go-review.googlesource.com/21241
Reviewed-by: Alan Donovan <adonovan@google.com>
The Node type ODOT and its variants all represent a selector, with a
simple name to the right of the dot. Before this change this was
represented by using an ONAME Node in the Right field. This ONAME node
served no useful purpose. This CL changes these Node types to store the
symbol in the Sym field instead, thus not requiring allocating a Node
for each selector.
When compiling x/tools/go/types this CL eliminates nearly 5000 calls to
newname and reduces the total number of Nodes allocated by about 6.6%.
It seems to cut compilation time by 1 to 2 percent.
Getting this right was somewhat subtle, and I added two dubious changes
to produce the exact same output as before. One is to ishairy in
inl.go: the ONAME node increased the cost of ODOT and friends by 1, and
I retained that, although really ODOT is not more expensive than any
other node. The other is to varexpr in walk.go: because the ONAME in
the Right field of an ODOT has no class, varexpr would always return
false for an ODOT, although in fact for some ODOT's it seemingly ought
to return true; I added an && false for now. I will send separate CLs,
that will break toolstash -cmp, to clean these up.
This CL passes toolstash -cmp.
Change-Id: I4af8a10cc59078c436130ce472f25abc3a9b2f80
Reviewed-on: https://go-review.googlesource.com/20890
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Currently, the only use for this is on the Left side of OKEY nodes
within struct literals. esc and fmt only care so they can recognize
that the ONAME nodes are actually field names, which need special
handling.
sinit additionally needs to know the field's offset within the struct,
which we can provide via Xoffset.
Passes toolstash/buildall.
Change-Id: I362d965e161f4d80fcd9c9bae0dfacc657dc0b29
Reviewed-on: https://go-review.googlesource.com/20676
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In addition to reflect.Value.Call, exported methods can be invoked
by the Func value in the reflect.Method struct. This CL has the
compiler track what functions get access to a legitimate reflect.Method
struct by looking for interface calls to either of:
Method(int) reflect.Method
MethodByName(string) (reflect.Method, bool)
This is a little overly conservative. If a user implements a type
with one of these methods without using the underlying calls on
reflect.Type, the linker will assume the worst and include all
exported methods. But it's cheap.
No change to any of the binary sizes reported in cl/20483.
For #14740
Change-Id: Ie17786395d0453ce0384d8b240ecb043b7726137
Reviewed-on: https://go-review.googlesource.com/20489
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
That was easy.
Fixes#14473.
Change-Id: I9d1d20a5c5a9b1423e6c72c0460ee4a78130864f
Reviewed-on: https://go-review.googlesource.com/20521
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Mix in several other minor cleanups, including adding some new methods
to Nodes: Index, Addr, SetIndex, SetNodes.
Passes toolstash -cmp.
Update #14473.
Change-Id: I8bd4ae3fde7c5e20ba66e7dd1654fbc70c3ddeb8
Reviewed-on: https://go-review.googlesource.com/20491
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This CL was automatically generated using a special-purpose AST
rewriting tool, followed by manual editing to put some comments back in
the right places and fix some bad line breaks.
The result is not perfect but it's a big step toward getting back to
sanity, and because it was automatically generated there is a decent
chance that it is correct.
Passes toolstash -cmp.
Update #14473.
Change-Id: I01c09078a6d78e2b008bc304d744b79469a38d3d
Reviewed-on: https://go-review.googlesource.com/20440
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Compile time is about the same. Getting rid of the nodeSeq interfaces,
particularly nodeSeqIterate, should produce some improvements.
Passes toolstash -cmp.
Update #14473.
Change-Id: I678abafdd9129c6cccb0ec980511932eaed496a0
Reviewed-on: https://go-review.googlesource.com/20343
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
It is only necessary in a few places, and this inlining will
simplify the transition away from NodeLists.
Passes toolstash -cmp.
Change-Id: I4ee9b4bf56ffa04df23e20a0a83b302d36b33510
Reviewed-on: https://go-review.googlesource.com/20290
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Found by temporarily flipping fields from *NodeList to Nodes and fixing
all the compilation errors. This CL does not actually change any
fields.
Passes toolstash -cmp.
Update #14473.
Change-Id: Ib98fa37e8752f96358224c973a743618a6a0e736
Reviewed-on: https://go-review.googlesource.com/20320
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Also fix some uses of nodeSeqIterator.Len, and fix the implementation in
nodesIterator.
Passes toolstash -cmp.
Update #14473.
Change-Id: I228871470234b7f1314ffd2aae8a4c0624c35f98
Reviewed-on: https://go-review.googlesource.com/20231
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Also rewrite bexport.go to use nodeSeqIterate.
The new setNodeSeq is a transitional generic function to set either a
NodeList or a slice to either a NodeList or a slice. This should permit
us to flip fields from *NodeList to []*Node, or Nodes, without changing
other code.
Passes toolstash -cmp.
Change-Id: I872cbfe45bc5f432595737c1f6da641c502b1ab6
Reviewed-on: https://go-review.googlesource.com/20194
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
I tried to write a program to convert *NodeList to Node, but ran into
too many problem cases. I'm backing off and trying a more iterative
approach using interfaces.
This CL adds an interface for iteration over either a *NodeList or a
Nodes. I changed typechecklist to use it, to show how it works. After
NodeList is eliminated, we can change the typechecklist parameter type
to Nodes.
Passes toolstash -cmp.
Change-Id: I5c7593714b020d20868b99151b1e7cadbbdbc397
Reviewed-on: https://go-review.googlesource.com/20190
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
The listsort function is no longer used, except in a test. Change the
test to use sort.Sort instead.
Change-Id: Ib634705cc1bc3b1d8fc3795bd4ed2894e6abc284
Reviewed-on: https://go-review.googlesource.com/19964
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Function bodies are not yet hooked up because the node structure is not
100% correct. This commit establishes that we can correctly write bodies
out and read them in again.
- export and import all exported inlined function bodies:
(export GO_GCFLAGS="-newexport"; sh all.bash) working
- inlined functions are not yet hooked up (just dropped on the floor)
- improved tracing output and error messages
- make mkbuiltin.go work for both textual and binary export data
so we can run tests with the new format
Change-Id: I70dc4de419df1b604389c3747041d6dba8730b0b
Reviewed-on: https://go-review.googlesource.com/16284
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Introduces a new types Nodes that can be used to replace NodeList.
Update #14473.
Change-Id: Id77c5dcae0cbeb898ba12dd46bd400aad408871c
Reviewed-on: https://go-review.googlesource.com/19969
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Save a few bytes in Func.
Passes toolstash -cmp.
Update #14473.
Change-Id: I824fa7d5cb2d93f6f59938ccd86114abcbea0043
Reviewed-on: https://go-review.googlesource.com/19968
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
By using a Pragma bit set (8 bits) rather than 8 booleans, also
reduce Func type size by 8 bytes (208B -> 200B on 64bit platforms,
116B -> 108B on 32bit platforms).
Change-Id: Ibb7e1f8c418a0b5bc6ff813cbdde7bc6f0013b5a
Reviewed-on: https://go-review.googlesource.com/19966
Reviewed-by: Dave Cheney <dave@cheney.net>
A slice uses less memory than a NodeList, and has better memory locality
when walking the list.
This uncovered a tricky case involving closures: the escape analysis
pass when run on a closure was appending to the Dcl list of the OCLOSURE
rather than the ODCLFUNC. This happened to work because they shared the
same NodeList. Fixed with a change to addrescapes, and a check to
Tempname to catch any recurrences.
This removes the last use of the listsort function outside of tests.
I'll send a separate CL to remove it.
Unfortunately, while this passes all tests, it does not pass toolstash
-cmp. The problem is that cmpstackvarlt does not fully determine the
sort order, and the change from listsort to sort.Sort, while generally
desirable, produces a different ordering. I could stage this by first
making cmpstackvarlt fully determined, but no matter what toolstash -cmp
is going to break at some point.
In my casual testing the compiler is 2.2% faster.
Update #14473.
Change-Id: I367d66daa4ec73ed95c14c66ccda3a2133ad95d5
Reviewed-on: https://go-review.googlesource.com/19919
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Consider this code:
func f(*int)
func g() {
p := new(int)
f(p)
}
where f is an assembly function.
In general liveness analysis assumes that during the call to f, p is dead
in this frame. If f has retained p, p will be found alive in f's frame and keep
the new(int) from being garbage collected. This is all correct and works.
We use the Go func declaration for f to give the assembly function
liveness information (the arguments are assumed live for the entire call).
Now consider this code:
func h1() {
p := new(int)
syscall.Syscall(1, 2, 3, uintptr(unsafe.Pointer(p)))
}
Here syscall.Syscall is taking the place of f, but because its arguments
are uintptr, the liveness analysis and the garbage collector ignore them.
Since p is no longer live in h once the call starts, if the garbage collector
scans the stack while the system call is blocked, it will find no reference
to the new(int) and reclaim it. If the kernel is going to write to *p once
the call finishes, reclaiming the memory is a mistake.
We can't change the arguments or the liveness information for
syscall.Syscall itself, both for compatibility and because sometimes the
arguments really are integers, and the garbage collector will get quite upset
if it finds an integer where it expects a pointer. The problem is that
these arguments are fundamentally untyped.
The solution we have taken in the syscall package's wrappers in past
releases is to insert a call to a dummy function named "use", to make
it look like the argument is live during the call to syscall.Syscall:
func h2() {
p := new(int)
syscall.Syscall(1, 2, 3, uintptr(unsafe.Pointer(p)))
use(unsafe.Pointer(p))
}
Keeping p alive during the call means that if the garbage collector
scans the stack during the system call now, it will find the reference to p.
Unfortunately, this approach is not available to users outside syscall,
because 'use' is unexported, and people also have to realize they need
to use it and do so. There is much existing code using syscall.Syscall
without a 'use'-like function. That code will fail very occasionally in
mysterious ways (see #13372).
This CL fixes all that existing code by making the compiler do the right
thing automatically, without any code modifications. That is, it takes h1
above, which is incorrect code today, and makes it correct code.
Specifically, if the compiler sees a foreign func definition (one
without a body) that has uintptr arguments, it marks those arguments
as "unsafe uintptrs". If it later sees the function being called
with uintptr(unsafe.Pointer(x)) as an argument, it arranges to mark x
as having escaped, and it makes sure to hold x in a live temporary
variable until the call returns, so that the garbage collector cannot
reclaim whatever heap memory x points to.
For now I am leaving the explicit calls to use in package syscall,
but they can be removed early in a future cycle (likely Go 1.7).
The rule has no effect on escape analysis, only on liveness analysis.
Fixes#13372.
Change-Id: I2addb83f70d08db08c64d394f9d06ff0a063c500
Reviewed-on: https://go-review.googlesource.com/18584
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This introduces a recursive variant of the go:nowritebarrier
annotation that prohibits write barriers not only in the annotated
function, but in all functions it calls, recursively. The error
message gives the shortest call stack from the annotated function to
the function containing the prohibited write barrier, including the
names of the functions and the line numbers of the calls.
To demonstrate the annotation, we apply it to gcmarkwb_m, the write
barrier itself.
This is a new annotation rather than a modification of the existing
go:nowritebarrier annotation because, for better or worse, there are
many go:nowritebarrier functions that do call functions with write
barriers. In most of these cases this is benign because the annotation
was conservative, but it prohibits simply coopting the existing
annotation.
Change-Id: I225ca483c8f699e8436373ed96349e80ca2c2479
Reviewed-on: https://go-review.googlesource.com/16554
Reviewed-by: Keith Randall <khr@golang.org>
Type Op is enfored now.
Type EType will need further CLs.
Added TODOs where Node.EType is used as a union type.
The TODOs have the format `TODO(marvin): Fix Node.EType union type.`.
Furthermore:
-The flag of Econv function in fmt.go is removed, since unused.
-Some cleaning along the way, e.g. declare vars first when getting initialized.
Passes go build -toolexec 'toolstash -cmp' -a std.
Fixes#11846
Change-Id: I908b955d5a78a195604970983fb9194bd9e9260b
Reviewed-on: https://go-review.googlesource.com/14956
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Marvin Stenger <marvin.stenger94@gmail.com>
