533280 - Outgoing function parameters can be clobbered

Status: VERIFIED FIXED

(Tamarin Graveyard :: Baseline JIT (CodegenLIR), defect, P1)

Description

[Edwin Smith]

Attachment: Extend lifetime of outgoing args to the function call even when an interior pointer is used.

In rare cases, it is possible for outgoing args to a function to be clobbered when a register spills, because the code lifetime of the allocated space for the args does not extend to the function call.

This only occurs on 32 bit machines and outgoing calls that contain at least one Number typed parameter, and is a result of optimizing the alignment of the double parameter, and passing an aligned interior pointer to the call.

Comment 1

[Edwin Smith]

Attachment: (v2) Extend lifetime of outgoing args to the function call even when an interior pointer is used.

Rebased patch, fixed the same problem in OP_newobject, found by inspection.

Comment 2

[Rick Reitmaier]

Comment on attachment 416426 [details] [diff] [review]
(v2) Extend lifetime of outgoing args to the function call even when an interior pointer is used.

r+ing, but we should follow up with another bug, since other LIR_callx's could encounter something similar.

Comment 3

[Edwin Smith]

I'm not going to submit the patch, working on a more complete fix now.

Comment 4

[Edwin Smith]

Attachment: (v3) Extend lifetime of outgoing args to the function call even when an interior pointer is used.

This adds a LIR_live that fixes the lifetime for every LIR_alloc, regardless of whether the pointer itself or an interior pointer is passed out to a function.

Comment 5

[Rick Reitmaier]

Comment on attachment 416570 [details] [diff] [review]
(v3)  Extend lifetime of outgoing args to the function call even when an interior pointer is used.

Although I doubt it will move the needle much curious how this affects performance.

Comment 6

[Edwin Smith]

Negligible effects, from my testing.  If anything i'd expect it to affect compile time slightly (slightly more LIR instructions to process) and run-time not at all.

Comment 7

[Edwin Smith]

Comment on attachment 416570 [details] [diff] [review]
(v3)  Extend lifetime of outgoing args to the function call even when an interior pointer is used.

pushed

Comment 9

[Chris Peyer]

Engineering work item.  Marking as verified.