avoid asserts over missing before state when generating safe Div/Rem nodes on AArch64 #226
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axel22
reviewed
Jun 16, 2017
| protected SafeSignedRemNode(ValueNode x, ValueNode y) { | ||
| super(TYPE, x, y); | ||
| } | ||
| @Override |
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Eclipseformat is complaining about a missing empty line between the methods.
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Restyled and pushed :-) Good to go? |
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@adinn Should be great - the merge should land soon! Thanks a lot! |
dougxc
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Jun 16, 2017
…safe div/rem on AArch64 (#226).
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The Problem:
This patch fixes the 12 CountedLoop unit tests that currently fail with an assert during code generation.
Diagnosis:
On AArch64 DIv/Rem nodes are replaced by a snippet which includes AArch64-specific SafeDiv/Rem nodes. The latter are cloned from the original DIv/Rem nodes with a null beforeState. Unfortunately, they inherit their generate method from the generic Div/Rem nodes. The inherited methods call gen.state(this) to retrieve the beforeState and construct a FrameState passed in the call to the generators emitDiv/Rem method. This blows up because the beforeState is null.
Fix:
The AArch64 generator's emitDiv/Rem methods ignore the state argument because they will never encounter a div by zero. So, there is no need to compute a frame state. The fix works by overriding the inherited methods and passing null for the frame state.
Testing:
After this patch the 12 failing CountedLoop unit tests all succeed.