[llvm] e5ad7f4 - [RISCV] Move RISCVIndirectBranchTracking before Branch Relaxation (#139993)

[via llvm-commits]

Author: Jesse Huang
Date: 2025-06-17T17:21:24+08:00
New Revision: e5ad7f4556ba4f31380153f70a8c6186926764e2

URL: https://github.com/llvm/llvm-project/commit/e5ad7f4556ba4f31380153f70a8c6186926764e2
DIFF: https://github.com/llvm/llvm-project/commit/e5ad7f4556ba4f31380153f70a8c6186926764e2.diff

LOG: [RISCV] Move RISCVIndirectBranchTracking before Branch Relaxation (#139993)

The `RISCVIndirectBranchTracking` pass inserts `lpad` instruction and
could change the basic block alignment, so this should not happen after
the branch relaxation as the adjusted offset is possible to exceed the
branch range.

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
    llvm/test/CodeGen/RISCV/O0-pipeline.ll
    llvm/test/CodeGen/RISCV/O3-pipeline.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index 8a47453cedcd3..0bea3bc432b66 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -570,6 +570,10 @@ 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());
 }
@@ -581,7 +585,6 @@ 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