[llvm] [RISCV] Move RISCVIndirectBranchTracking before Branch Relaxation (PR #139993)

[Jesse Huang via llvm-commits]

https://github.com/jaidTw updated https://github.com/llvm/llvm-project/pull/139993

>From 06f4e7d9755ddbbb9b53fdbe613cbf3d5456fd08 Mon Sep 17 00:00:00 2001
From: Jesse Huang <jesse.huang at sifive.com>
Date: Mon, 5 May 2025 03:40:30 -0700
Subject: [PATCH 1/2] [RISCV] Move RISCVIndirectBranchTracking before Branch
 Relaxation

---
 llvm/lib/Target/RISCV/RISCVTargetMachine.cpp | 2 +-
 llvm/test/CodeGen/RISCV/O0-pipeline.ll       | 2 +-
 llvm/test/CodeGen/RISCV/O3-pipeline.ll       | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index 7fb64be3975d5..28283c9fd5b6d 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -570,6 +570,7 @@ void RISCVPassConfig::addPreEmitPass() {
     addPass(createMachineCopyPropagationPass(true));
   if (TM->getOptLevel() >= CodeGenOptLevel::Default)
     addPass(createRISCVLateBranchOptPass());
+  addPass(createRISCVIndirectBranchTrackingPass());
   addPass(&BranchRelaxationPassID);
   addPass(createRISCVMakeCompressibleOptPass());
 }
@@ -581,7 +582,6 @@ void RISCVPassConfig::addPreEmitPass2() {
     // ensuring return instruction is detected correctly.
     addPass(createRISCVPushPopOptimizationPass());
   }
-  addPass(createRISCVIndirectBranchTrackingPass());
   addPass(createRISCVExpandPseudoPass());
 
   // Schedule the expansion of AMOs at the last possible moment, avoiding the
diff --git a/llvm/test/CodeGen/RISCV/O0-pipeline.ll b/llvm/test/CodeGen/RISCV/O0-pipeline.ll
index 694662eab1681..8714b286374a5 100644
--- a/llvm/test/CodeGen/RISCV/O0-pipeline.ll
+++ b/llvm/test/CodeGen/RISCV/O0-pipeline.ll
@@ -62,6 +62,7 @@
 ; CHECK-NEXT:       Insert fentry calls
 ; CHECK-NEXT:       Insert XRay ops
 ; CHECK-NEXT:       Implement the 'patchable-function' attribute
+; CHECK-NEXT:       RISC-V Indirect Branch Tracking
 ; CHECK-NEXT:       Branch relaxation pass
 ; CHECK-NEXT:       RISC-V Make Compressible
 ; CHECK-NEXT:       Contiguously Lay Out Funclets
@@ -73,7 +74,6 @@
 ; CHECK-NEXT:       Lazy Machine Block Frequency Analysis
 ; CHECK-NEXT:       Machine Optimization Remark Emitter
 ; CHECK-NEXT:       Stack Frame Layout Analysis
-; CHECK-NEXT:       RISC-V Indirect Branch Tracking
 ; CHECK-NEXT:       RISC-V pseudo instruction expansion pass
 ; CHECK-NEXT:       RISC-V atomic pseudo instruction expansion pass
 ; CHECK-NEXT:       Unpack machine instruction bundles
diff --git a/llvm/test/CodeGen/RISCV/O3-pipeline.ll b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
index 19de864422bc5..c7f70a9d266c2 100644
--- a/llvm/test/CodeGen/RISCV/O3-pipeline.ll
+++ b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
@@ -195,6 +195,7 @@
 ; CHECK-NEXT:       Implement the 'patchable-function' attribute
 ; CHECK-NEXT:       Machine Copy Propagation Pass
 ; CHECK-NEXT:       RISC-V Late Branch Optimisation Pass
+; CHECK-NEXT:       RISC-V Indirect Branch Tracking
 ; CHECK-NEXT:       Branch relaxation pass
 ; CHECK-NEXT:       RISC-V Make Compressible
 ; CHECK-NEXT:       Contiguously Lay Out Funclets
@@ -210,7 +211,6 @@
 ; CHECK-NEXT:       Stack Frame Layout Analysis
 ; CHECK-NEXT:       RISC-V Zcmp move merging pass
 ; CHECK-NEXT:       RISC-V Zcmp Push/Pop optimization pass
-; CHECK-NEXT:       RISC-V Indirect Branch Tracking
 ; CHECK-NEXT:       RISC-V pseudo instruction expansion pass
 ; CHECK-NEXT:       RISC-V atomic pseudo instruction expansion pass
 ; CHECK-NEXT:       Unpack machine instruction bundles

>From be3cebdafc95bc90574a0d65c067e975baccae84 Mon Sep 17 00:00:00 2001
From: Jesse Huang <jesse.huang at sifive.com>
Date: Thu, 15 May 2025 01:11:37 -0700
Subject: [PATCH 2/2] fixup! Add comment

---
 llvm/lib/Target/RISCV/RISCVTargetMachine.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index 28283c9fd5b6d..c048243db4982 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -570,6 +570,9 @@ void RISCVPassConfig::addPreEmitPass() {
     addPass(createMachineCopyPropagationPass(true));
   if (TM->getOptLevel() >= CodeGenOptLevel::Default)
     addPass(createRISCVLateBranchOptPass());
+  // The IndirectBranchTrackingPass inserts lpad and could have changed the
+  // basic block alignment. It must be done before Branch Relaxation to
+  // prevent the adjusted offset exceeding the branch range.
   addPass(createRISCVIndirectBranchTrackingPass());
   addPass(&BranchRelaxationPassID);
   addPass(createRISCVMakeCompressibleOptPass());