From 98cae0e8835a1eb8fcb0e43870c04ed934cc51ac Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Thu, 13 Aug 2026 19:38:37 +0800
Subject: [CodeGen] Match LLVM branch relaxation semantics

---
 backend/utils/TableGen/Common/CodeGenInstruction.cpp | 5 +++++
 backend/utils/TableGen/Common/CodeGenTarget.h        | 1 +
 backend/utils/TableGen/InstrInfoEmitter.cpp          | 5 +++--
 3 files changed, 9 insertions(+), 2 deletions(-)

(limited to 'backend/utils')

diff --git a/backend/utils/TableGen/Common/CodeGenInstruction.cpp b/backend/utils/TableGen/Common/CodeGenInstruction.cpp
index fc6b400..d06fbfc 100644
--- a/backend/utils/TableGen/Common/CodeGenInstruction.cpp
+++ b/backend/utils/TableGen/Common/CodeGenInstruction.cpp
@@ -428,6 +428,7 @@ CodeGenTarget::normalizeImplicitRegisters(const std::vector<SourceImplicitRegist
         .Flags = {},
         .SchedulingClass = HasSchedulingClass ? SchedulingClass->second : 0,
         .EncodingCategory = HasEncodingCategory ? EncodingCategory->second : 0,
+        .SizeInBytes = Instruction.SizeInBytes,
         .AssemblyFormat = HasAssemblyFormat ? AssemblyFormat->second : 0,
         .RequiresMemoryOperands = Instruction.RequiresMemoryOperands,
         .Owner = std::string(*Owner),
@@ -547,6 +548,10 @@ CodeGenTarget::normalizeImplicitRegisters(const std::vector<SourceImplicitRegist
       fail(Instruction.Range, "instruction pseudo flags, owner, and deadline are inconsistent");
       return false;
     }
+    if (Normalized.SizeInBytes != 0 && !HasFlag("ProducesCode")) {
+      fail(Instruction.Range, "only code-producing instructions can declare a byte size");
+      return false;
+    }
     if (Normalized.RequiresMemoryOperands && !HasFlag("MayLoad") && !HasFlag("MayStore")) {
       fail(Instruction.Range, "memory operand requirements need a load or store instruction flag");
       return false;
diff --git a/backend/utils/TableGen/Common/CodeGenTarget.h b/backend/utils/TableGen/Common/CodeGenTarget.h
index cc2697c..139cfc8 100644
--- a/backend/utils/TableGen/Common/CodeGenTarget.h
+++ b/backend/utils/TableGen/Common/CodeGenTarget.h
@@ -155,6 +155,7 @@ struct NormalizedInstruction final {
   std::vector<std::string> Flags;
   std::uint32_t SchedulingClass = 0;
   std::uint32_t EncodingCategory = 0;
+  std::uint32_t SizeInBytes = 0;
   std::uint32_t AssemblyFormat = 0;
   bool RequiresMemoryOperands = false;
   std::string Owner;
diff --git a/backend/utils/TableGen/InstrInfoEmitter.cpp b/backend/utils/TableGen/InstrInfoEmitter.cpp
index 795a718..b06134f 100644
--- a/backend/utils/TableGen/InstrInfoEmitter.cpp
+++ b/backend/utils/TableGen/InstrInfoEmitter.cpp
@@ -179,8 +179,9 @@ std::string emitInstructionInfo(const NormalizedTargetModel &Model) {
       Output << "InstructionFlag::" << Flag << ", ";
     Output << "}, .SchedulingClass = SchedulingClassID::fromValue(" << Instruction.SchedulingClass
            << "), .EncodingCategory = EncodingCategoryID::fromValue("
-           << Instruction.EncodingCategory << "), .AssemblyFormat = AssemblyFormatID::fromValue("
-           << Instruction.AssemblyFormat << "), .RequiresMemoryOperands = "
+           << Instruction.EncodingCategory << "), .SizeInBytes = " << Instruction.SizeInBytes
+           << ", .AssemblyFormat = AssemblyFormatID::fromValue(" << Instruction.AssemblyFormat
+           << "), .RequiresMemoryOperands = "
            << (Instruction.RequiresMemoryOperands ? "true" : "false")
            << ", .Owner = PseudoOwner::" << Instruction.Owner
            << ", .Deadline = PipelineStage::" << Instruction.Deadline
-- 
cgit v1.2.3