996422 - Split MIRType_Magic into one distinct type per magic constant

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, defect)

Description

[Shu-yu Guo [:shu]]

While discussing some bugs that part 1 of bug 716647, Jan suggested that the
MIRTypes for magic arguments vs the magic optimized out value have separate
types. This worked well, and got rid of a lot of nasty corner cases around
phi-merging magic constants. While rewriting that patch, I found it necessary
to refactor some TI and Ion stuff, so putting these refactor patches here.

Comment 1

[Shu-yu Guo [:shu]]

Attachment: Make TypeSets work with MIRTypes directly

Ion is the sole consumer of TI, so I see no reason to go from TI -> JSValueType
-> MIRType, especially since this means we can lose precision about the magic
arguments type: if the JSVAL_TYPE_ARGUMENTS came from TI, then it must mean
MIRType_MagicOptimizedArguments, since TI doesn't observe other magic types in
general. But if Ion tries to get the MIRType of some arbitrary magic value, it
shouldn't be MIRType_MagicOptimizedArguments.

This patches changes TI's JIT-oriented methods to work with MIRTypes directly
instead of via JSValueType.

Comment 2

[Shu-yu Guo [:shu]]

Attachment: Split MIRType_Magic into one type for each magic constant

Actually does the split inside Ion.

Comment 3

[Jan de Mooij [:jandem]]

Comment on attachment 8406620 [details] [diff] [review]
Make TypeSets work with MIRTypes directly

Review of attachment 8406620 [details] [diff] [review]:
-----------------------------------------------------------------

I wasn't sure about this at first, but after looking at the patch it's nice to get rid of these JSValueType <-> MIRType conversions everywhere.

Comment 4

[Jan de Mooij [:jandem]]

Comment on attachment 8406621 [details] [diff] [review]
Split MIRType_Magic into one type for each magic constant

Review of attachment 8406621 [details] [diff] [review]:
-----------------------------------------------------------------

Nice.

Comment 5

[Shu-yu Guo [:shu]]

Try: https://tbpl.mozilla.org/?tree=Try&rev=be33b96ad263 (bottom 2 commits)

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/7756408df0dd
https://hg.mozilla.org/mozilla-central/rev/ff7d23524ff6