[llvm] [BOLT][AArch64] Expand cmpbr when reversing would overflow (PR #202998)

[Paschalis Mpeis via llvm-commits]

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@@ -2171,38 +2191,88 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
     }
   }
 
-  bool isReversibleBranch(const MCInst &Inst) const override {
+  BranchLivenessInfo
+  createBranchLivenessInfo(BinaryFunction &BF,
+                           DataflowInfoManager &DIM) const override {
+    BranchLivenessInfo Info;
+    LivenessAnalysis &LA = DIM.getLivenessAnalysis();
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paschalis-mpeis wrote:

Can't we defer `getLivenessAnalysis` until we encounter the first cmpbr in a function?

https://github.com/llvm/llvm-project/pull/202998