[PATCH] D79893: [SCEV] Constant fold MultExpr before applying depth limit.

[Denis Antrushin via Phabricator via llvm-commits]

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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:3006
+  if (Depth > MaxArithDepth || hasHugeExpression(Ops))
+    return getOrCreateMulExpr(Ops, Flags);
+
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efriedma wrote:
> I think you need to rearrange the code a bit more: with the current version of the patch, we increase the depth before checking the current depth.
> 
> The general idea makes sense: we should perform optimizations that aren't recursive before the depth check.
Eli, could you explain?
Do you mean `Depth + 1` used in calls above on constant folding path?
My reasoning was following:
If we're already at depth limit (`Depth == MaxArithDepth`) then we don't want to recurse into possible expensive folding.
On the other hand, constant folding will be attempted anyway, which is what we want here.

Does it makes sense?





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