[RISCV] Insert simple landing pad before indirect jumps for Zicfilp.

This patch is based on llvm#91855. This patch inserts simple landing pad
([pr])before indirct jumps. And also make option riscv-landing-pad-label
influence this feature.
[pr]: riscv-non-isa/riscv-elf-psabi-doc#417

Author: Yeting Kuo

llvm/lib/Target/RISCV/CMakeLists.txt

@@ -44,6 +44,7 @@ add_llvm_target(RISCVCodeGen
   RISCVInstrInfo.cpp
   RISCVISelDAGToDAG.cpp
   RISCVISelLowering.cpp
+  RISCVLandingPadSetup.cpp
   RISCVMachineFunctionInfo.cpp
   RISCVMergeBaseOffset.cpp
   RISCVOptWInstrs.cpp

llvm/lib/Target/RISCV/RISCV.h

@@ -37,6 +37,9 @@ void initializeRISCVIndirectBranchTrackingPass(PassRegistry &);
 FunctionPass *createRISCVISelDag(RISCVTargetMachine &TM,
                                  CodeGenOptLevel OptLevel);
 
+FunctionPass *createRISCVLandingPadSetupPass();
+void initializeRISCVLandingPadSetupPass(PassRegistry &);
+
 FunctionPass *createRISCVMakeCompressibleOptPass();
 void initializeRISCVMakeCompressibleOptPass(PassRegistry &);
 

llvm/lib/Target/RISCV/RISCVIndirectBranchTracking.cpp

@@ -23,7 +23,7 @@
 
 using namespace llvm;
 
-static cl::opt<uint32_t> PreferredLandingPadLabel(
+cl::opt<uint32_t> PreferredLandingPadLabel(
     "riscv-landing-pad-label", cl::ReallyHidden,
     cl::desc("Use preferred fixed label for all labels"));
 

llvm/lib/Target/RISCV/RISCVLandingPadSetup.cpp

@@ -0,0 +1,85 @@
+//===------------ RISCVLandingPadSetup.cpp ---------------------------------==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This is a RISC-V pass to setup landing pad labels for indirect jumps.
+// Currently it is only supported fixed labels.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RISCV.h"
+#include "RISCVInstrInfo.h"
+#include "RISCVSubtarget.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/InitializePasses.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "riscv-lpad-setup"
+#define PASS_NAME "RISC-V Landing Pad Setup"
+
+extern cl::opt<uint32_t> PreferredLandingPadLabel;
+
+namespace {
+
+class RISCVLandingPadSetup : public MachineFunctionPass {
+public:
+  static char ID;
+
+  RISCVLandingPadSetup() : MachineFunctionPass(ID) {}
+
+  bool runOnMachineFunction(MachineFunction &F) override;
+
+  StringRef getPassName() const override { return PASS_NAME; }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+};
+
+} // end anonymous namespace
+
+bool RISCVLandingPadSetup::runOnMachineFunction(MachineFunction &MF) {
+  const auto &STI = MF.getSubtarget<RISCVSubtarget>();
+  const RISCVInstrInfo &TII = *STI.getInstrInfo();
+
+  if (!STI.hasStdExtZicfilp())
+    return false;
+
+  bool Changed = false;
+  for (MachineBasicBlock &MBB : MF)
+    for (MachineInstr &MI : llvm::make_early_inc_range(MBB)) {
+      if (!MI.isIndirectBranch() &&
+          MI.getOpcode() != RISCV::PseudoCALLIndirectNonX7 &&
+          MI.getOpcode() != RISCV::PseudoTAILIndirectNonX7)
+        continue;
+      uint32_t Label = 0;
+      if (PreferredLandingPadLabel.getNumOccurrences() > 0) {
+        if (!isUInt<20>(PreferredLandingPadLabel))
+          report_fatal_error(
+              "riscv-landing-pad-label=<val>, <val> needs to fit in "
+              "unsigned 20-bits");
+        Label = PreferredLandingPadLabel;
+      }
+      BuildMI(MBB, MI, MI.getDebugLoc(), TII.get(RISCV::LUI), RISCV::X7)
+          .addImm(Label);
+      MachineInstrBuilder(MF, &MI).addUse(RISCV::X7, RegState::ImplicitKill);
+      Changed = true;
+    }
+
+  return Changed;
+}
+
+INITIALIZE_PASS(RISCVLandingPadSetup, DEBUG_TYPE, PASS_NAME, false, false)
+
+char RISCVLandingPadSetup::ID = 0;
+
+FunctionPass *llvm::createRISCVLandingPadSetupPass() {
+  return new RISCVLandingPadSetup();
+}

llvm/lib/Target/RISCV/RISCVTargetMachine.cpp

@@ -545,6 +545,7 @@ void RISCVPassConfig::addPreRegAlloc() {
   addPass(createRISCVInsertReadWriteCSRPass());
   addPass(createRISCVInsertWriteVXRMPass());
   addPass(createRISCVInsertVSETVLIPass());
+  addPass(createRISCVLandingPadSetupPass());
 }
 
 void RISCVPassConfig::addFastRegAlloc() {

llvm/test/CodeGen/RISCV/O0-pipeline.ll

@@ -43,6 +43,7 @@
 ; CHECK-NEXT:       RISC-V Insert Read/Write CSR Pass
 ; CHECK-NEXT:       RISC-V Insert Write VXRM Pass
 ; CHECK-NEXT:       RISC-V Insert VSETVLI pass
+; CHECK-NEXT:       RISC-V Landing Pad Setup
 ; CHECK-NEXT:       Init Undef Pass
 ; CHECK-NEXT:       Eliminate PHI nodes for register allocation
 ; CHECK-NEXT:       Two-Address instruction pass

llvm/test/CodeGen/RISCV/O3-pipeline.ll

@@ -118,6 +118,7 @@
 ; CHECK-NEXT:       RISC-V Insert Read/Write CSR Pass
 ; CHECK-NEXT:       RISC-V Insert Write VXRM Pass
 ; CHECK-NEXT:       RISC-V Insert VSETVLI pass
+; CHECK-NEXT:       RISC-V Landing Pad Setup
 ; CHECK-NEXT:       Detect Dead Lanes
 ; CHECK-NEXT:       Init Undef Pass
 ; CHECK-NEXT:       Process Implicit Definitions

llvm/test/CodeGen/RISCV/lpad.ll

@@ -13,15 +13,16 @@ define void @indirctbr(i32 %i, ptr %p) {
 ; RV32-NEXT:    addi a2, a2, %lo(.L__const.indirctbr.addr)
 ; RV32-NEXT:    add a0, a2, a0
 ; RV32-NEXT:    lw a0, 0(a0)
+; RV32-NEXT:    lui t2, 0
 ; RV32-NEXT:    jr a0
 ; RV32-NEXT:    .p2align 2
-; RV32-NEXT:  .Ltmp0: # Block address taken
+; RV32-NEXT:  .Ltmp3: # Block address taken
 ; RV32-NEXT:  .LBB0_1: # %labelA
 ; RV32-NEXT:    lpad 0
 ; RV32-NEXT:    li a0, 1
 ; RV32-NEXT:    sw a0, 0(a1)
 ; RV32-NEXT:    .p2align 2
-; RV32-NEXT:  .Ltmp1: # Block address taken
+; RV32-NEXT:  .Ltmp4: # Block address taken
 ; RV32-NEXT:  .LBB0_2: # %labelB
 ; RV32-NEXT:    lpad 0
 ; RV32-NEXT:    li a0, 2
@@ -37,15 +38,16 @@ define void @indirctbr(i32 %i, ptr %p) {
 ; RV64-NEXT:    slli a0, a0, 3
 ; RV64-NEXT:    add a0, a2, a0
 ; RV64-NEXT:    ld a0, 0(a0)
+; RV64-NEXT:    lui t2, 0
 ; RV64-NEXT:    jr a0
 ; RV64-NEXT:    .p2align 2
-; RV64-NEXT:  .Ltmp0: # Block address taken
+; RV64-NEXT:  .Ltmp3: # Block address taken
 ; RV64-NEXT:  .LBB0_1: # %labelA
 ; RV64-NEXT:    lpad 0
 ; RV64-NEXT:    li a0, 1
 ; RV64-NEXT:    sw a0, 0(a1)
 ; RV64-NEXT:    .p2align 2
-; RV64-NEXT:  .Ltmp1: # Block address taken
+; RV64-NEXT:  .Ltmp4: # Block address taken
 ; RV64-NEXT:  .LBB0_2: # %labelB
 ; RV64-NEXT:    lpad 0
 ; RV64-NEXT:    li a0, 2
@@ -65,12 +67,65 @@ labelB:                                           ; preds = %labelA, %entry
   ret void
 }
 
-; Check external linkage function.
-define void @external() {
-; CHECK-LABEL: external:
+; Check call.
+define void @call(ptr %0) {
+; CHECK-LABEL: call:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    lpad 0
-; CHECK-NEXT:    ret
+; CHECK-NEXT:    lui t2, 0
+; CHECK-NEXT:    jr a0
+  tail call void %0()
+  ret void
+}
+
+; Check invoke.
+declare dso_local i32 @__gxx_personality_v0(...)
+define void @invoke(ptr %f) personality ptr @__gxx_personality_v0 {
+; RV32-LABEL: invoke:
+; RV32:       # %bb.0: # %entry
+; RV32-NEXT:    lpad 0
+; RV32-NEXT:    addi sp, sp, -16
+; RV32-NEXT:    .cfi_def_cfa_offset 16
+; RV32-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32-NEXT:    .cfi_offset ra, -4
+; RV32-NEXT:  .Ltmp0:
+; RV32-NEXT:    lui t2, 0
+; RV32-NEXT:    jalr a0
+; RV32-NEXT:  .Ltmp1:
+; RV32-NEXT:  .LBB2_1: # %try.cont
+; RV32-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32-NEXT:    addi sp, sp, 16
+; RV32-NEXT:    ret
+; RV32-NEXT:  .LBB2_2: # %lpad
+; RV32-NEXT:  .Ltmp2:
+; RV32-NEXT:    j .LBB2_1
+;
+; RV64-LABEL: invoke:
+; RV64:       # %bb.0: # %entry
+; RV64-NEXT:    lpad 0
+; RV64-NEXT:    addi sp, sp, -16
+; RV64-NEXT:    .cfi_def_cfa_offset 16
+; RV64-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64-NEXT:    .cfi_offset ra, -8
+; RV64-NEXT:  .Ltmp0:
+; RV64-NEXT:    lui t2, 0
+; RV64-NEXT:    jalr a0
+; RV64-NEXT:  .Ltmp1:
+; RV64-NEXT:  .LBB2_1: # %try.cont
+; RV64-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64-NEXT:    addi sp, sp, 16
+; RV64-NEXT:    ret
+; RV64-NEXT:  .LBB2_2: # %lpad
+; RV64-NEXT:  .Ltmp2:
+; RV64-NEXT:    j .LBB2_1
+entry:
+  invoke void %f() to label %try.cont unwind label %lpad
+
+lpad:
+  %0 = landingpad { ptr, i32 } cleanup
+  br label %try.cont
+
+try.cont:
   ret void
 }