[BOLT] Refactor MCInst target symbol lookup. NFCI

[maksfb]

In analyzeInstructionForFuncReference(), use MCPlusBuilder interface while scanning symbolic operands of MCInst. Should be NFC on x86, but will make the function work on other architectures. Note that it's currently unused on non-x86 as its functionality is exclusive to safe ICF that runs on x86 only.

[llvmbot]

@llvm/pr-subscribers-bolt

Author: Maksim Panchenko (maksfb)

Changes

In analyzeInstructionForFuncReference(), use MCPlusBuilder interface while scanning symbolic operands of MCInst. Should be NFC on x86, but will make the function work on other architectures. Note that it's currently unused on non-x86 as its functionality is exclusive to safe ICF that runs on x86 only.

---

Full diff: https://github.com/llvm/llvm-project/pull/129131.diff

1 Files Affected:

• (modified) bolt/lib/Core/BinaryFunction.cpp (+4-8)

diff --git a/bolt/lib/Core/BinaryFunction.cpp b/bolt/lib/Core/BinaryFunction.cpp
index ff5eb5cf6e1eb..5a1ff58b72f75 100644
--- a/bolt/lib/Core/BinaryFunction.cpp
+++ b/bolt/lib/Core/BinaryFunction.cpp
@@ -1544,15 +1544,11 @@ MCSymbol *BinaryFunction::registerBranch(uint64_t Src, uint64_t Dst) {
 }
 
 void BinaryFunction::analyzeInstructionForFuncReference(const MCInst &Inst) {
-  for (const MCOperand &Op : MCPlus::primeOperands(Inst)) {
-    if (!Op.isExpr())
+  for (unsigned OpNum = 0; OpNum < MCPlus::getNumPrimeOperands(Inst); ++OpNum) {
+    const MCSymbol *Symbol = BC.MIB->getTargetSymbol(Inst, OpNum);
+    if (!Symbol)
       continue;
-    const MCExpr &Expr = *Op.getExpr();
-    if (Expr.getKind() != MCExpr::SymbolRef)
-      continue;
-    const MCSymbol &Symbol = cast<MCSymbolRefExpr>(Expr).getSymbol();
-    // Set HasAddressTaken for a function regardless of the ICF level.
-    if (BinaryFunction *BF = BC.getFunctionForSymbol(&Symbol))
+    if (BinaryFunction *BF = BC.getFunctionForSymbol(Symbol))
       BF->setHasAddressTaken(true);
   }
 }