[llvm] [SystemZ] Fix compile time regression in adjustInliningThreshold(). (PR #137527)

[Nikita Popov via llvm-commits]

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@@ -92,29 +91,38 @@ unsigned SystemZTTIImpl::adjustInliningThreshold(const CallBase *CB) const {
     }
   }
 
-  // Give bonus for globals used much in both caller and callee.
-  std::set<const GlobalVariable *> CalleeGlobals;
-  std::set<const GlobalVariable *> CallerGlobals;
-  for (const GlobalVariable &Global : M->globals())
-    for (const User *U : Global.users())
-      if (const Instruction *User = dyn_cast<Instruction>(U)) {
-        if (User->getParent()->getParent() == Callee)
-          CalleeGlobals.insert(&Global);
-        if (User->getParent()->getParent() == Caller)
-          CallerGlobals.insert(&Global);
+  // Give bonus for globals used much in both caller and a relatively small
+  // callee.
+  if (Callee->getInstructionCount() < 200) {
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nikic wrote:

getInstructionCount() is going to iterate over the whole function to determine the instruction count. It's usually better to always do the analysis and just bail out if it inspects too many instructions.

https://github.com/llvm/llvm-project/pull/137527