[llvm] [AMDGPU] Preserve resource requirements through call-graph cycles (PR #221625)

[Shilei Tian via llvm-commits]

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@@ -247,33 +252,170 @@ bool AMDGPUMCExpr::evaluateInstPrefSize(MCValue &Res,
 
 bool AMDGPUMCExpr::isSymbolUsedInExpression(const MCSymbol *Sym,
                                             const MCExpr *E) {
-  switch (E->getKind()) {
-  case MCExpr::Constant:
-    return false;
-  case MCExpr::Unary:
-    return isSymbolUsedInExpression(
-        Sym, static_cast<const MCUnaryExpr *>(E)->getSubExpr());
-  case MCExpr::Binary: {
-    const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(E);
-    return isSymbolUsedInExpression(Sym, BE->getLHS()) ||
-           isSymbolUsedInExpression(Sym, BE->getRHS());
-  }
-  case MCExpr::SymbolRef: {
-    const MCSymbol &S = static_cast<const MCSymbolRefExpr *>(E)->getSymbol();
-    if (S.isVariable())
-      return isSymbolUsedInExpression(Sym, S.getVariableValue());
-    return &S == Sym;
-  }
-  case MCExpr::Specifier:
-  case MCExpr::Target: {
-    auto *TE = static_cast<const AMDGPUMCExpr *>(E);
-    for (const MCExpr *E : TE->getArgs())
-      if (isSymbolUsedInExpression(Sym, E))
+  SmallVector<const MCExpr *, 16> WorkList{E};
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shiltian wrote:

this is like a function refinement. might just do a NFC.

https://github.com/llvm/llvm-project/pull/221625