SCEVExpander: Don't look at uses of constants

[arsenm]

This could be more relaxed, and look for uses of globals in
the same function but no tests apparently depend on that.

[arsenm]

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• IR: Remove uselist for constantdata #134692
• SCEVExpander: Don't look at uses of constants #134691 👈 (View in Graphite)
• LICM: Avoid looking at use list of constant data #134690
• PHITransAddr: Avoid looking at constant use lists #134689
• SimplifyLibCalls: Skip sincospi optimization for ConstantData #134688
• ObjCARCContract: Use stripPointerCastsAndAliases #134275
• ObjCARC: Drop pointer bitcast handling #134274
• main

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[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Matt Arsenault (arsenm)

Changes

This could be more relaxed, and look for uses of globals in
the same function but no tests apparently depend on that.

---

Full diff: https://github.com/llvm/llvm-project/pull/134691.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp (+16-13)

diff --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index 41bf202230e22..e25ec6c3b2a58 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -111,20 +111,23 @@ Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
 
   Value *Ret = nullptr;
 
-  // Check to see if there is already a cast!
-  for (User *U : V->users()) {
-    if (U->getType() != Ty)
-      continue;
-    CastInst *CI = dyn_cast<CastInst>(U);
-    if (!CI || CI->getOpcode() != Op)
-      continue;
+  if (!isa<Constant>(V)) {
+    // Check to see if there is already a cast!
+    for (User *U : V->users()) {
+      if (U->getType() != Ty)
+        continue;
+      CastInst *CI = dyn_cast<CastInst>(U);
+      if (!CI || CI->getOpcode() != Op)
+        continue;
 
-    // Found a suitable cast that is at IP or comes before IP. Use it. Note that
-    // the cast must also properly dominate the Builder's insertion point.
-    if (IP->getParent() == CI->getParent() && &*BIP != CI &&
-        (&*IP == CI || CI->comesBefore(&*IP))) {
-      Ret = CI;
-      break;
+      // Found a suitable cast that is at IP or comes before IP. Use it. Note
+      // that the cast must also properly dominate the Builder's insertion
+      // point.
+      if (IP->getParent() == CI->getParent() && &*BIP != CI &&
+          (&*IP == CI || CI->comesBefore(&*IP))) {
+        Ret = CI;
+        break;
+      }
     }
   }
 

[nikic]

LGTM

[fhahn]

LGTM, thanks

[arsenm]

30ae47e