[llvm] [BOLT][AArch64] Speedup `computeInstructionSize` (PR #121106)

[via llvm-commits]

https://github.com/liusy58 updated https://github.com/llvm/llvm-project/pull/121106

>From df25731d1f066265b10045f185de3ef0eb09bad5 Mon Sep 17 00:00:00 2001
From: liusy58 <liusy58 at linux.alibaba.com>
Date: Wed, 25 Dec 2024 19:45:08 +0800
Subject: [PATCH] [BOLT][AArch64]  Speedup `computeInstructionSize`

---
 bolt/include/bolt/Core/BinaryContext.h           | 3 +++
 bolt/include/bolt/Core/MCPlusBuilder.h           | 5 +++++
 bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp | 8 ++++++++
 3 files changed, 16 insertions(+)

diff --git a/bolt/include/bolt/Core/BinaryContext.h b/bolt/include/bolt/Core/BinaryContext.h
index 115e59ca0697e5..18cfb42cbe5bf8 100644
--- a/bolt/include/bolt/Core/BinaryContext.h
+++ b/bolt/include/bolt/Core/BinaryContext.h
@@ -1363,6 +1363,9 @@ class BinaryContext {
     if (std::optional<uint32_t> Size = MIB->getSize(Inst))
       return *Size;
 
+    if (std::optional<uint32_t> Size = MIB->getInstructionSize(Inst))
+      return *Size;
+
     if (!Emitter)
       Emitter = this->MCE.get();
     SmallString<256> Code;
diff --git a/bolt/include/bolt/Core/MCPlusBuilder.h b/bolt/include/bolt/Core/MCPlusBuilder.h
index 3634fed9757ceb..5d77e6faff2fc6 100644
--- a/bolt/include/bolt/Core/MCPlusBuilder.h
+++ b/bolt/include/bolt/Core/MCPlusBuilder.h
@@ -1204,6 +1204,11 @@ class MCPlusBuilder {
   /// Get instruction size specified via annotation.
   std::optional<uint32_t> getSize(const MCInst &Inst) const;
 
+  /// Get target-specific instruction size.
+  virtual std::optional<uint32_t> getInstructionSize(const MCInst &Inst) const {
+    return std::nullopt;
+  }
+
   /// Set instruction size.
   void setSize(MCInst &Inst, uint32_t Size) const;
 
diff --git a/bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp b/bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
index 7e08e5c81d26ff..406dc9b09e3ee1 100644
--- a/bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
+++ b/bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
@@ -1790,6 +1790,14 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
   }
 
   uint16_t getMinFunctionAlignment() const override { return 4; }
+
+  std::optional<uint32_t>
+  getInstructionSize(const MCInst &Inst) override const {
+    if (isPseudo(Inst)) {
+      return 0;
+    }
+    return 4;
+  }
 };
 
 } // end anonymous namespace