Go's SSA instructions only operate on registers. For example, an add
instruction would read two registers, do the addition and then write
to a register. WebAssembly's instructions, on the other hand, operate
on the stack. The add instruction first pops two values from the stack,
does the addition, then pushes the result to the stack. To fulfill
Go's semantics, one needs to map Go's single add instruction to
4 WebAssembly instructions:
- Push the value of local variable A to the stack
- Push the value of local variable B to the stack
- Do addition
- Write value from stack to local variable C
Now consider that B was set to the constant 42 before the addition:
- Push constant 42 to the stack
- Write value from stack to local variable B
This works, but is inefficient. Instead, the stack is used directly
by inlining instructions if possible. With inlining it becomes:
- Push the value of local variable A to the stack (add)
- Push constant 42 to the stack (constant)
- Do addition (add)
- Write value from stack to local variable C (add)
Note that the two SSA instructions can not be generated sequentially
anymore, because their WebAssembly instructions are interleaved.
Design doc: https://docs.google.com/document/d/131vjr4DH6JFnb-blm_uRdaC0_Nv3OUwjEY5qVCxCup4
Updates #18892
Change-Id: Ie35e1c0bebf4985fddda0d6330eb2066f9ad6dec
Reviewed-on: https://go-review.googlesource.com/103535
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When the compiler decomposes a user variable, track its origin so that
it can be recomposed during DWARF generation.
Change-Id: Ia71c7f8e7f4d65f0652f1c97b0dda5d9cad41936
Reviewed-on: https://go-review.googlesource.com/50878
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
I learned from CL 41770 that valState’s size
matters to compiler performance.
Encode that knowledge in a test.
Change-Id: I7c0fde6a4cf460017619dbcce1c1ddaa7af10239
Reviewed-on: https://go-review.googlesource.com/44737
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
When package ssa was created, Type was in package gc.
To avoid circular dependencies, we used an interface (ssa.Type)
to represent type information in SSA.
In the Go 1.9 cycle, gri extricated the Type type from package gc.
As a result, we can now use it in package ssa.
Now, instead of package types depending on package ssa,
it is the other way.
This is a more sensible dependency tree,
and helps compiler performance a bit.
Though this is a big CL, most of the changes are
mechanical and uninteresting.
Interesting bits:
* Add new singleton globals to package types for the special
SSA types Memory, Void, Invalid, Flags, and Int128.
* Add two new Types, TSSA for the special types,
and TTUPLE, for SSA tuple types.
ssa.MakeTuple is now types.NewTuple.
* Move type comparison result constants CMPlt, CMPeq, and CMPgt
to package types.
* We had picked the name "types" in our rules for the handy
list of types provided by ssa.Config. That conflicted with
the types package name, so change it to "typ".
* Update the type comparison routine to handle tuples and special
types inline.
* Teach gc/fmt.go how to print special types.
* We can now eliminate ElemTypes in favor of just Elem,
and probably also some other duplicated Type methods
designed to return ssa.Type instead of *types.Type.
* The ssa tests were using their own dummy types,
and they were not particularly careful about types in general.
Of necessity, this CL switches them to use *types.Type;
it does not make them more type-accurate.
Unfortunately, using types.Type means initializing a bit
of the types universe.
This is prime for refactoring and improvement.
This shrinks ssa.Value; it now fits in a smaller size class
on 64 bit systems. This doesn't have a giant impact,
though, since most Values are preallocated in a chunk.
name old alloc/op new alloc/op delta
Template 37.9MB ± 0% 37.7MB ± 0% -0.57% (p=0.000 n=10+8)
Unicode 28.9MB ± 0% 28.7MB ± 0% -0.52% (p=0.000 n=10+10)
GoTypes 110MB ± 0% 109MB ± 0% -0.88% (p=0.000 n=10+10)
Flate 24.7MB ± 0% 24.6MB ± 0% -0.66% (p=0.000 n=10+10)
GoParser 31.1MB ± 0% 30.9MB ± 0% -0.61% (p=0.000 n=10+9)
Reflect 73.9MB ± 0% 73.4MB ± 0% -0.62% (p=0.000 n=10+8)
Tar 25.8MB ± 0% 25.6MB ± 0% -0.77% (p=0.000 n=9+10)
XML 41.2MB ± 0% 40.9MB ± 0% -0.80% (p=0.000 n=10+10)
[Geo mean] 40.5MB 40.3MB -0.68%
name old allocs/op new allocs/op delta
Template 385k ± 0% 386k ± 0% ~ (p=0.356 n=10+9)
Unicode 343k ± 1% 344k ± 0% ~ (p=0.481 n=10+10)
GoTypes 1.16M ± 0% 1.16M ± 0% -0.16% (p=0.004 n=10+10)
Flate 238k ± 1% 238k ± 1% ~ (p=0.853 n=10+10)
GoParser 320k ± 0% 320k ± 0% ~ (p=0.720 n=10+9)
Reflect 957k ± 0% 957k ± 0% ~ (p=0.460 n=10+8)
Tar 252k ± 0% 252k ± 0% ~ (p=0.133 n=9+10)
XML 400k ± 0% 400k ± 0% ~ (p=0.796 n=10+10)
[Geo mean] 428k 428k -0.01%
Removing all the interface calls helps non-trivially with CPU, though.
name old time/op new time/op delta
Template 178ms ± 4% 173ms ± 3% -2.90% (p=0.000 n=94+96)
Unicode 85.0ms ± 4% 83.9ms ± 4% -1.23% (p=0.000 n=96+96)
GoTypes 543ms ± 3% 528ms ± 3% -2.73% (p=0.000 n=98+96)
Flate 116ms ± 3% 113ms ± 4% -2.34% (p=0.000 n=96+99)
GoParser 144ms ± 3% 140ms ± 4% -2.80% (p=0.000 n=99+97)
Reflect 344ms ± 3% 334ms ± 4% -3.02% (p=0.000 n=100+99)
Tar 106ms ± 5% 103ms ± 4% -3.30% (p=0.000 n=98+94)
XML 198ms ± 5% 192ms ± 4% -2.88% (p=0.000 n=92+95)
[Geo mean] 178ms 173ms -2.65%
name old user-time/op new user-time/op delta
Template 229ms ± 5% 224ms ± 5% -2.36% (p=0.000 n=95+99)
Unicode 107ms ± 6% 106ms ± 5% -1.13% (p=0.001 n=93+95)
GoTypes 696ms ± 4% 679ms ± 4% -2.45% (p=0.000 n=97+99)
Flate 137ms ± 4% 134ms ± 5% -2.66% (p=0.000 n=99+96)
GoParser 176ms ± 5% 172ms ± 8% -2.27% (p=0.000 n=98+100)
Reflect 430ms ± 6% 411ms ± 5% -4.46% (p=0.000 n=100+92)
Tar 128ms ±13% 123ms ±13% -4.21% (p=0.000 n=100+100)
XML 239ms ± 6% 233ms ± 6% -2.50% (p=0.000 n=95+97)
[Geo mean] 220ms 213ms -2.76%
Change-Id: I15c7d6268347f8358e75066dfdbd77db24e8d0c1
Reviewed-on: https://go-review.googlesource.com/42145
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
XPos is a compact (8 instead of 16 bytes on a 64bit machine) source
position representation. There is a 1:1 correspondence between each
XPos and each regular Pos, translated via a global table.
In some sense this brings back the LineHist, though positions can
track line and column information; there is a O(1) translation
between the representations (no binary search), and the translation
is factored out.
The size increase with the prior change is brought down again and
the compiler speed is in line with the master repo (measured on
the same "quiet" machine as for prior change):
name old time/op new time/op delta
Template 256ms ± 1% 262ms ± 2% ~ (p=0.063 n=5+4)
Unicode 132ms ± 1% 135ms ± 2% ~ (p=0.063 n=5+4)
GoTypes 891ms ± 1% 871ms ± 1% -2.28% (p=0.016 n=5+4)
Compiler 3.84s ± 2% 3.89s ± 2% ~ (p=0.413 n=5+4)
MakeBash 47.1s ± 1% 46.2s ± 2% ~ (p=0.095 n=5+5)
name old user-ns/op new user-ns/op delta
Template 309M ± 1% 314M ± 2% ~ (p=0.111 n=5+4)
Unicode 165M ± 1% 172M ± 9% ~ (p=0.151 n=5+5)
GoTypes 1.14G ± 2% 1.12G ± 1% ~ (p=0.063 n=5+4)
Compiler 5.00G ± 1% 4.96G ± 1% ~ (p=0.286 n=5+4)
Change-Id: Icc570cc60ab014d8d9af6976f1f961ab8828cc47
Reviewed-on: https://go-review.googlesource.com/34506
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This replaces the src.Pos LineHist-based position tracking with
the syntax.Pos implementation and updates all uses.
The LineHist table is not used anymore - the respective code is still
there but should be removed eventually. CL forthcoming.
Passes toolstash -cmp when comparing to the master repo (with the
exception of a couple of swapped assembly instructions, likely due
to different instruction scheduling because the line-based sorting
has changed; though this is won't affect correctness).
The sizes of various important compiler data structures have increased
significantly (see the various sizes_test.go files); this is probably
the reason for an increase of compilation times (to be addressed). Here
are the results of compilebench -count 5, run on a "quiet" machine (no
apps running besides a terminal):
name old time/op new time/op delta
Template 256ms ± 1% 280ms ±15% +9.54% (p=0.008 n=5+5)
Unicode 132ms ± 1% 132ms ± 1% ~ (p=0.690 n=5+5)
GoTypes 891ms ± 1% 917ms ± 2% +2.88% (p=0.008 n=5+5)
Compiler 3.84s ± 2% 3.99s ± 2% +3.95% (p=0.016 n=5+5)
MakeBash 47.1s ± 1% 47.2s ± 2% ~ (p=0.841 n=5+5)
name old user-ns/op new user-ns/op delta
Template 309M ± 1% 326M ± 2% +5.18% (p=0.008 n=5+5)
Unicode 165M ± 1% 168M ± 4% ~ (p=0.421 n=5+5)
GoTypes 1.14G ± 2% 1.18G ± 1% +3.47% (p=0.008 n=5+5)
Compiler 5.00G ± 1% 5.16G ± 1% +3.12% (p=0.008 n=5+5)
Change-Id: I241c4246cdff627d7ecb95cac23060b38f9775ec
Reviewed-on: https://go-review.googlesource.com/34273
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Keep track of how many uses each Value has. Each appearance in
Value.Args and in Block.Control counts once.
The number of uses of a value is generically useful to
constrain rewrite rules. For instance, we might want to
prevent merging index operations into loads if the same
index expression is used lots of times.
But I have one use in particular for which the use count is required.
We must make sure we don't combine ops with loads if the load has
more than one use. Otherwise, we may split a single load
into multiple loads and that breaks perceived behavior in
the presence of races. In particular, the load of m.state
in sync/mutex.go:Lock can't be done twice. (I have a separate
CL which triggers the mutex failure. This CL has a test which
demonstrates a similar failure.)
Change-Id: Icaafa479239f48632a069d0c3f624e6ebc6b1f0e
Reviewed-on: https://go-review.googlesource.com/20790
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Todd Neal <todd@tneal.org>
Fix some test output while we're here.
Change-Id: I265cedc222e078eff120f268b92451e12b0400b2
Reviewed-on: https://go-review.googlesource.com/20294
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
