https://llvm.org/bugs/show_bug.cgi?id=27660
Bug ID: 27660
Summary: phi node arguments oscillate with passes
jump-threading and loop-simplify
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 16313
--> https://llvm.org/bugs/attachment.cgi?id=16313&action=edit
jump-threading_loop-simplify.ll
When using the flags -jump-threading and -loop-simplify on the attached IR
(jump-threading_loop-simplify.ll) the phi nodes will keep flipping. This was
produced by using the attached IR and using the output as input back to opt.
For example:
$ ./opt -S -jump-threading -loop-simplify jump-threading_loop-simplify.ll >
out1.ll
$ ./opt -S -jump-threading -loop-simplify out1.ll > out2.ll
$ ./opt -S -jump-threading -loop-simplify out2.ll > out3.ll
diff out2.ll out1.ll
1c1
< ; ModuleID = 'out1.ll'
---
> ; ModuleID = 'jump-threading_loop-simplify.ll'
29,30c29,30
< _ZNK4pugi8xml_text5_dataEv.exit.loopexit: ; preds = %for.inc.i,
%for.body.i
< %.ph = phi %"struct.pugi::xml_node_struct.1.85.421"* [ null, %for.inc.i ],
[ undef, %for.body.i ]
---
> _ZNK4pugi8xml_text5_dataEv.exit.loopexit: ; preds = %for.body.i,
> %for.inc.i
> %.ph = phi %"struct.pugi::xml_node_struct.1.85.421"* [ undef, %for.body.i
> ], [ null, %for.inc.i ]
$ diff out3.ll out2.ll
1c1
< ; ModuleID = 'out2.ll'
---
> ; ModuleID = 'out1.ll'
30c30
< %.ph = phi %"struct.pugi::xml_node_struct.1.85.421"* [ undef, %for.body.i
], [ null, %for.inc.i ]
---
> %.ph = phi %"struct.pugi::xml_node_struct.1.85.421"* [ null, %for.inc.i ],
> [ undef, %for.body.i ]
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