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cmd/compile: panic: internal error: can't locate after prolog value (with -N -l) #45948

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ALTree opened this issue May 4, 2021 · 4 comments
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cmd/compile: panic: internal error: can't locate after prolog value (with -N -l) #45948

ALTree opened this issue May 4, 2021 · 4 comments
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FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
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Go1.17

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@ALTree
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ALTree commented May 4, 2021 

$ gotip version
go version devel go1.17-da7496d841 Tue May 4 17:37:39 2021 +0000 linux/amd64

package p

func f(p int) {
L:
	goto L

}

$ gotip tool compile -N -l crash.go

panic: internal error: f=f: can't locate after prolog value

goroutine 7 [running]:
cmd/compile/internal/ssa.BuildFuncDebugNoOptimized(0xc000172400, 0xc00037cea0, 0x0, 0xd1e2b8)
	/home/alberto/go/src/cmd/compile/internal/ssa/debug.go:1366 +0xf54
cmd/compile/internal/ssagen.genssa(0xc00037cea0, 0xc000402a80)
	/home/alberto/go/src/cmd/compile/internal/ssagen/ssa.go:6988 +0xc16
cmd/compile/internal/ssagen.Compile(0xc0001382c0, 0x0)
	/home/alberto/go/src/cmd/compile/internal/ssagen/pgen.go:175 +0x266
cmd/compile/internal/gc.compileFunctions.func2.1()
	/home/alberto/go/src/cmd/compile/internal/gc/compile.go:136 +0x65
created by cmd/compile/internal/gc.compileFunctions.func2
	/home/alberto/go/src/cmd/compile/internal/gc/compile.go:134 +0xcf

Doesn't crash on Go1.16.
Doesn't crash on GOEXPERIMENT=noregabiargs.

Reduced from a gosmith crasher.

cc @cherrymui @aclements @dr2chase
@ALTree ALTree added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label May 4, 2021
@ALTree ALTree added this to the Go1.17 milestone May 4, 2021
@cherrymui
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cc @thanm

Maybe we can change it to be best effort.

@thanm thanm self-assigned this May 4, 2021
@thanm
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thanm commented May 4, 2021

I'll take a look.

@gopherbot
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Change https://golang.org/cl/316752 mentions this issue: cmd/compile: handle degenerate entry blocks in -N debug gen

@gopherbot
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Change https://golang.org/cl/317089 mentions this issue: cmd/compile: debug trace output for -N variable location gen

gopherbot pushed a commit that referenced this issue May 5, 2021
@thanm
cmd/compile: debug trace output for -N variable location gen
caf4c94 
Add some rudimentary debug trace output for -N location list
generation if "-d=ssa/locationlists" is set.

Updates #45948.

Change-Id: If1a95730538a6e7def7ebe1ece1a71da8e5f0975
Reviewed-on: https://go-review.googlesource.com/c/go/+/317089
Trust: Than McIntosh <thanm@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
@golang golang locked and limited conversation to collaborators May 5, 2022
@rsc rsc unassigned thanm Jun 23, 2022
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