IROutliner: Do not look at use lists of constant phi inputs

[arsenm]

Theoretically this does a worse job with globals but this is not
covered by existing tests

[arsenm]

• IROutliner: Do not look at use lists of constant phi inputs #135019 👈 (View in Graphite)
• IROutliner: Use ValueMapper to remap constants in a function #134850
• main

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[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Matt Arsenault (arsenm)

Changes

Theoretically this does a worse job with globals but this is not
covered by existing tests

---

Full diff: https://github.com/llvm/llvm-project/pull/135019.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/IPO/IROutliner.cpp (+2-1)

diff --git a/llvm/lib/Transforms/IPO/IROutliner.cpp b/llvm/lib/Transforms/IPO/IROutliner.cpp
index 8c5946fb07c65..eec869d57a6db 100644
--- a/llvm/lib/Transforms/IPO/IROutliner.cpp
+++ b/llvm/lib/Transforms/IPO/IROutliner.cpp
@@ -1126,7 +1126,8 @@ static void analyzeExitPHIsForOutputUses(
     // outside of the single PHINode we should not skip over it.
     for (unsigned Idx : IncomingVals) {
       Value *V = PN.getIncomingValue(Idx);
-      if (outputHasNonPHI(V, Idx, PN, PotentialExitsFromRegion, RegionBlocks)) {
+      if (!isa<Constant>(V) &&
+          outputHasNonPHI(V, Idx, PN, PotentialExitsFromRegion, RegionBlocks)) {
         OutputsWithNonPhiUses.insert(V);
         OutputsReplacedByPHINode.erase(V);
         continue;

[dtcxzyw]

LGTM. Thank you!