cmd/compile: ICE building issue5162.go on linux-amd64-noopt

[heschi]

2022-08-23T20:24:43-723a279/linux-amd64-noopt

# go run run.go -- fixedbugs/issue5162.go
exit status 2
# command-line-arguments
../../tmp/797079598/tmp__.go:16136:27: internal compiler error: bvset: index 0 is out of bounds with length 0

cc @golang/runtime

[randall77]

I'm not sure how this could happen. This appears to happen when compiling the main routine, which is just

func main() {
   call1()
   call2()
   ...
   callN()
}

Then out of nowhere the liveness analysis tries to add a local variable of type string to the pointer bitmap. Not sure where that variable comes from - there shouldn't be any local variables in this situation. The error is because there's no room in the bitmap for such a thing - the bitmap is 0 length.
Strange.

I can't reproduce. Not sure if there's anything to be done other than to see if it happens again.

[heschi]

Another strange failure on noopt:

https://build.golang.org/log/ea4753ef9daf73937e1434aff8161e8cf7d600a9

# internal/profile [internal/profile.test]
panic: runtime error: index out of range [805] with length 0

goroutine 93 [running]:
panic({0x115cb00, 0xc00002dce0})
	/workdir/go/src/runtime/panic.go:987 +0x3cc fp=0xc001196940 sp=0xc001196880 pc=0x43c9ec
runtime.goPanicIndex(0x325, 0x0)
	/workdir/go/src/runtime/panic.go:113 +0x7f fp=0xc001196980 sp=0xc001196940 pc=0x43aa7f
cmd/compile/internal/ssa.AutoVar(0xc000f96030)
	/workdir/go/src/cmd/compile/internal/ssa/value.go:553 +0x34a fp=0xc001196ab8 sp=0xc001196980 pc=0xdeacea
cmd/compile/internal/liveness.affectedVar(0xc000f96030)
	/workdir/go/src/cmd/compile/internal/liveness/plive.go:323 +0x85 fp=0xc001196c08 sp=0xc001196ab8 pc=0xdfb585
cmd/compile/internal/liveness.(*liveness).valueEffects(0xc0005e6f00, 0xc000f96030)
	/workdir/go/src/cmd/compile/internal/liveness/plive.go:254 +0x65 fp=0xc001196cb8 sp=0xc001196c08 pc=0xdfb1c5
cmd/compile/internal/liveness.(*liveness).prologue(0xc0005e6f00)
	/workdir/go/src/cmd/compile/internal/liveness/plive.go:642 +0x126 fp=0xc001196dc8 sp=0xc001196cb8 pc=0xdfdd06
cmd/compile/internal/liveness.Compute(0xc00052f7c0, 0xc000093d40, 0x0, 0xc000691c00)
	/workdir/go/src/cmd/compile/internal/liveness/plive.go:1338 +0x176 fp=0xc001196ff0 sp=0xc001196dc8 pc=0xe041d6
cmd/compile/internal/ssagen.genssa(0xc000093d40, 0xc000691c00)
	/workdir/go/src/cmd/compile/internal/ssagen/ssa.go:6894 +0x158 fp=0xc001197dd0 sp=0xc001196ff0 pc=0xe4d7b8
cmd/compile/internal/ssagen.Compile(0xc00052f7c0, 0x0)
	/workdir/go/src/cmd/compile/internal/ssagen/pgen.go:197 +0x331 fp=0xc001197f48 sp=0xc001197dd0 pc=0xe10f11
cmd/compile/internal/gc.compileFunctions.func4.1(0x0)
	/workdir/go/src/cmd/compile/internal/gc/compile.go:153 +0x47 fp=0xc001197fa0 sp=0xc001197f48 pc=0x1092d87
cmd/compile/internal/gc.compileFunctions.func3.1()
	/workdir/go/src/cmd/compile/internal/gc/compile.go:140 +0x52 fp=0xc001197fe0 sp=0xc001197fa0 pc=0x1092f32
runtime.goexit()
	/workdir/go/src/runtime/asm_amd64.s:1594 +0x1 fp=0xc001197fe8 sp=0xc001197fe0 pc=0x472261
created by cmd/compile/internal/gc.compileFunctions.func3
	/workdir/go/src/cmd/compile/internal/gc/compile.go:138 +0xa5

[bcmills]

https://build.golang.org/log/a47c465045059703073a129d4ca97d6da963bd1e:

# net [syscall.test]
<autogenerated>:1: internal compiler error: bvset: index 0 is out of bounds with length 0


goroutine 522 [running]:
runtime/debug.Stack()
	/workdir/go/src/runtime/debug/stack.go:24 +0x7a
cmd/compile/internal/base.FatalfAt({0x1, 0x1000}, {0x11bd50f, 0x30}, {0xc0030268f0, 0x2, 0x2})
	/workdir/go/src/cmd/compile/internal/base/print.go:227 +0x22a
cmd/compile/internal/base.Fatalf({0x11bd50f, 0x30}, {0xc0030268f0, 0x2, 0x2})
	/workdir/go/src/cmd/compile/internal/base/print.go:196 +0x56
cmd/compile/internal/bitvec.BitVec.Set({0x0, {0x17782c0, 0x0, 0x0}}, 0x0)
	/workdir/go/src/cmd/compile/internal/bitvec/bv.go:81 +0x14d
cmd/compile/internal/typebits.Set(0xc000370770, 0x0, {0x0, {0x17782c0, 0x0, 0x0}})
	/workdir/go/src/cmd/compile/internal/typebits/typebits.go:38 +0x607
cmd/compile/internal/liveness.(*liveness).pointerMap(0xc00320a000, {0xc, {0xc000b6c138, 0x1, 0x1}}, {0xc003206000, 0xc, 0x10}, {0x3, {0xc000b6c174, ...}}, ...)
	/workdir/go/src/cmd/compile/internal/liveness/plive.go:433 +0x18f
cmd/compile/internal/liveness.(*liveness).emit(0xc00320a000)
	/workdir/go/src/cmd/compile/internal/liveness/plive.go:1316 +0x625
cmd/compile/internal/liveness.Compute(0xc0005e7b80, 0xc002e4c9c0, 0x0, 0xc003202000)
	/workdir/go/src/cmd/compile/internal/liveness/plive.go:1372 +0x3c5
cmd/compile/internal/ssagen.genssa(0xc002e4c9c0, 0xc003202000)
	/workdir/go/src/cmd/compile/internal/ssagen/ssa.go:6906 +0x158
cmd/compile/internal/ssagen.Compile(0xc0005e7b80, 0x1)
	/workdir/go/src/cmd/compile/internal/ssagen/pgen.go:197 +0x325
cmd/compile/internal/gc.compileFunctions.func4.1(0x1)
	/workdir/go/src/cmd/compile/internal/gc/compile.go:153 +0x47
cmd/compile/internal/gc.compileFunctions.func3.1()
	/workdir/go/src/cmd/compile/internal/gc/compile.go:140 +0x52
created by cmd/compile/internal/gc.compileFunctions.func3
	/workdir/go/src/cmd/compile/internal/gc/compile.go:138 +0xa5

FAIL	syscall [build failed]

[bcmills]

Looks like just the two bvset errors so far... but two points makes a line, and so far that line looks to me like a Go 1.20 regression. 😞

greplogs -l -e 'internal compiler error: bvset: index 0'
2022-09-06T16:59:58-e1e88d6/linux-amd64-noopt
2022-08-23T20:24:43-723a279/linux-amd64-noopt

[cuonglm]

Another one: https://storage.googleapis.com/go-build-log/146812cd/linux-amd64-noopt_2b85daaa.log

[mknyszek]

We're currently thinking this is a runtime issue causing a compilation failure via memory corruption. It's almost certainly related to #54906 and #54907.

[mknyszek]

@mdempsky also pointed out that the compiler we're running is also noopt.

[cherrymui]

@mknyszek asked whether this is related to #54596 . I tried the experiments there to see if they help here. The answer is no, neither CL there helps, nor disabling async preemption. So it is something else. Still looking.

[prattmic]

I looked through the noopt builder on the dashboard, and https://build.golang.org/log/f29160132769be9817908c039fdb7984f61846cb (at https://go.dev/cl/424904) is the earliest "random" failure I see. So the culprit CL is hopefully a nearby parent, though given the low failure rate there are lots of candidates.

[gopherbot]

Change https://go.dev/cl/431919 mentions this issue: runtime: make mSpanStateBox accessors nosplit