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x/tools/go/ssa: slice to array conversion has the wrong type #57790

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aykevl opened this issue Jan 13, 2023 · 3 comments
Closed

x/tools/go/ssa: slice to array conversion has the wrong type #57790

aykevl opened this issue Jan 13, 2023 · 3 comments
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@timothy-king
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FrozenDueToAge Tools This label describes issues relating to any tools in the x/tools repository.
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@aykevl
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aykevl commented Jan 13, 2023 •
edited

What version of Go are you using (go version)?

$ go version
go version go1.20rc2 linux/arm64

And I'm using the latest version of x/tools/go/ssa: 03eac81

Does this issue reproduce with the latest release?

No, slice to array conversions were added in Go 1.20.

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/home/ayke/.cache/go-build"
GOENV="/home/ayke/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/ayke/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/ayke"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_arm64"
GOVCS=""
GOVERSION="go1.20rc2"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/home/ayke/src/tinygo/tools/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build6976675=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I created a simple Go file with the following contents:

package main

func sliceToArray(s []int) [4]int {
        return [4]int(s)
}

Then I dumped the SSA output using ssadump:

$ ssadump -build CFI slice2array.go
# Name: command-line-arguments.init
# Package: command-line-arguments
# Synthetic: package initializer
func init():
0:                                                                entry P:0 S:0
        return

# Name: command-line-arguments.sliceToArray
# Package: command-line-arguments
# Location: /home/ayke/tmp/slice2array.go:3:6
# Locals:
#   0:  t2 [4]int
func sliceToArray(s []int) [4]int:
0:                                                                entry P:0 S:2
        t0 = slice to array pointer *[4]int <- []int (s)                *[4]int
        t1 = t0 == nil:*[4]int                                             bool
        if t1 goto 1 else 2
1:                                                     slicetoarray.nil P:1 S:1
        t2 = local [4]int ()                                            *[4]int
        jump 3
2:                                                  slicetoarray.nonnil P:1 S:1
        jump 3
3:                                                    slicetoarray.done P:2 S:0
        t3 = phi [1: t2, 2: t0] #slicetoarray                            [4]int
        t4 = *t3                                                         [4]int
        return t4

The problem here is that t3 has the wrong type. It should be *[4]int (a pointer) but instead it is [4]int (an array). This triggers an issue on the following line:

        t4 = *t3                                                         [4]int

Here, t3 (which should be of pointer type but is an array here) is dereferenced. This leads to a panic in my code, which expects to dereference a pointer and not an array.
@gopherbot gopherbot added the Tools This label describes issues relating to any tools in the x/tools repository. label Jan 13, 2023
@gopherbot gopherbot added this to the Unreleased milestone Jan 13, 2023
@ianlancetaylor
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CC @timothy-king @adonovan

@gopherbot
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Change https://go.dev/cl/462175 mentions this issue: go/ssa: fix phi node type in slice to array conversion

@gopherbot
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Change https://go.dev/cl/462050 mentions this issue: go/ssa: sanity check the types of phi nodes

gopherbot pushed a commit to golang/tools that referenced this issue Jan 17, 2023
@timothy-king
go/ssa: sanity check the types of phi nodes
d34a055 
Adds a sanity check that the types of phi edges are types.Identical
to the Phi instruction.

This would have caught golang/go#57790.

Change-Id: I9818fc47fda368bfc009bfe4de66e23de759f6ca
Reviewed-on: https://go-review.googlesource.com/c/tools/+/462050
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Tim King <taking@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
aykevl added a commit to tinygo-org/tinygo that referenced this issue Feb 6, 2023
@aykevl
all: update x/tools/go/ssa to include slice-to-array bugfix
082bdd8 
For the bugfix, see: golang/go#57790
@aykevl aykevl mentioned this issue Feb 6, 2023
Merged
deadprogram pushed a commit to tinygo-org/tinygo that referenced this issue Feb 7, 2023
@aykevl @deadprogram
all: update x/tools/go/ssa to include slice-to-array bugfix
0b0ae19 
For the bugfix, see: golang/go#57790
waj334 pushed a commit to waj334/tinygo that referenced this issue Feb 7, 2023
@aykevl @waj334
all: update x/tools/go/ssa to include slice-to-array bugfix
7aaac16 
For the bugfix, see: golang/go#57790
deadprogram pushed a commit to tinygo-org/tinygo that referenced this issue Feb 14, 2023
@aykevl @deadprogram
all: update x/tools/go/ssa to include slice-to-array bugfix
482d094 
For the bugfix, see: golang/go#57790
waj334 pushed a commit to waj334/tinygo that referenced this issue Feb 19, 2023
@aykevl @waj334
all: update x/tools/go/ssa to include slice-to-array bugfix
9e58cbb 
For the bugfix, see: golang/go#57790
waj334 pushed a commit to waj334/tinygo that referenced this issue Feb 24, 2023
@aykevl @waj334
all: update x/tools/go/ssa to include slice-to-array bugfix
4edfb62 
For the bugfix, see: golang/go#57790
LiuJiazheng pushed a commit to LiuJiazheng/tinygo that referenced this issue Aug 20, 2023
@aykevl @LiuJiazheng
all: update x/tools/go/ssa to include slice-to-array bugfix
ba83f09 
For the bugfix, see: golang/go#57790
@golang golang locked and limited conversation to collaborators Jan 17, 2024
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@aykevl @timothy-king @ianlancetaylor @gopherbot