[Polly] Make CodeGeneration handle PHI nodes in exit block

[Meinersbur]

Summary

PHI nodes are moved into the region. This node has the identity of the previous exit node so the references in Scop/ScopStmt do not need to be updated.

Such PHI nodes cannot yet occur without changes upstream (ScopInfo, TempScopInfo, ScopDetection) which will follow.

[jdoerfert]

I do not understand the commit message, could you explain it to me or make it more verbose? Additionally I somehow missed the intention.

lib/CodeGen/CodeGeneration.cpp

105 ↗

(On Diff #31586)

There is a new range style loop for this pattern.

122 ↗

(On Diff #31586)

I'm not a fan of blocks only to enforce indention.

123 ↗

(On Diff #31586)

space missing and ExitBB instead of BB?

129 ↗

(On Diff #31586)

if there are multiple regions should we call setregionfor multiple times? Isn't only the first or the last call the right/important one?

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(On Diff #31586)

I do not understand this part.

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(On Diff #31586)

I thought there is a predessors function or something that hides the make range?

[Meinersbur]

This comment was removed by Meinersbur.

[Meinersbur]

Uploaded wrong diff previously

[Meinersbur]

Actually found the predecessors function

[jdoerfert]

Some more comments but I still do not understand the part starting at line 131 in lib/CodeGen/CodeGeneration.cpp.

lib/CodeGen/CodeGeneration.cpp

97 ↗

(On Diff #31603)

typo and format of the comment.

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(On Diff #31603)

What does "keeps its identity" mean?

[Meinersbur]

Add splitBlockNonPredecessors that was once in D11867.
Style changes and incorporated comments.

[Meinersbur]

Merged into D11870

lib/CodeGen/CodeGeneration.cpp

99 ↗

(On Diff #31603)

memory address

135 ↗

(On Diff #31601)

There are not or at least I haven't seen them.

lib/Analysis/ScopInfo.cpp

   if (!Schedule)
     Schedule = isl_schedule_empty(getParamSpace());
 
+  // Build the statement for PHIs in the exit block (never nested in a
+  // scopped-loop)
+  isl_schedule *StmtSchedule =
+      buildBBScopStmt(getRegion().getExit(), TempScop, getRegion(), NestLoops);
+  Schedule = ScheduleCombineSequence(Schedule, StmtSchedule);
+
   realignParams();
   addParameterBounds();
   simplifyAssumedContext();