[SPIRV] Added lowering for the debugtrap intrinsic

[SubashBoopathi]

Mapped llvm.debugtrap intrinsic to OpNop in the SPIR-V backend, since SPIR-V has no direct equivalent with tests.

[github-actions]

Thank you for submitting a Pull Request (PR) to the LLVM Project!

This PR will be automatically labeled and the relevant teams will be notified.

If you wish to, you can add reviewers by using the "Reviewers" section on this page.

If this is not working for you, it is probably because you do not have write permissions for the repository. In which case you can instead tag reviewers by name in a comment by using @ followed by their GitHub username.

If you have received no comments on your PR for a week, you can request a review by "ping"ing the PR by adding a comment “Ping”. The common courtesy "ping" rate is once a week. Please remember that you are asking for valuable time from other developers.

If you have further questions, they may be answered by the LLVM GitHub User Guide.

You can also ask questions in a comment on this PR, on the LLVM Discord or on the forums.

[llvmbot]

@llvm/pr-subscribers-backend-spir-v

Author: Subash B (SubashBoopathi)

Changes

Mapped llvm.debugtrap intrinsic to OpNop in the SPIR-V backend, since SPIR-V has no direct equivalent with tests.

---

Full diff: https://github.com/llvm/llvm-project/pull/157442.diff

2 Files Affected:

• (modified) llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp (+13-1)
• (added) llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll (+15)

diff --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index 6608b3f2cbefd..ec28d1e1c15cb 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -197,6 +197,8 @@ class SPIRVInstructionSelector : public InstructionSelector {
 
   bool selectOverflowArith(Register ResVReg, const SPIRVType *ResType,
                            MachineInstr &I, unsigned Opcode) const;
+  bool selectDebugTrap(Register ResVReg, const SPIRVType *ResType,
+                       MachineInstr &I) const;
 
   bool selectIntegerDot(Register ResVReg, const SPIRVType *ResType,
                         MachineInstr &I, bool Signed) const;
@@ -951,16 +953,26 @@ bool SPIRVInstructionSelector::spvSelect(Register ResVReg,
   // represent code after lowering or intrinsics which are not implemented but
   // should not crash when found in a customer's LLVM IR input.
   case TargetOpcode::G_TRAP:
-  case TargetOpcode::G_DEBUGTRAP:
   case TargetOpcode::G_UBSANTRAP:
   case TargetOpcode::DBG_LABEL:
     return true;
+  case TargetOpcode::G_DEBUGTRAP:
+    return selectDebugTrap(ResVReg, ResType, I);
 
   default:
     return false;
   }
 }
 
+bool SPIRVInstructionSelector::selectDebugTrap(Register ResVReg,
+                                               const SPIRVType *ResType,
+                                               MachineInstr &I) const {
+  unsigned Opcode = SPIRV::OpNop;
+  MachineBasicBlock &BB = *I.getParent();
+  return BuildMI(BB, I, I.getDebugLoc(), TII.get(Opcode))
+      .constrainAllUses(TII, TRI, RBI);
+}
+
 bool SPIRVInstructionSelector::selectExtInst(Register ResVReg,
                                              const SPIRVType *ResType,
                                              MachineInstr &I,
diff --git a/llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll b/llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll
new file mode 100644
index 0000000000000..3f5fedf243cde
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll
@@ -0,0 +1,15 @@
+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv32-unknown-unknown %s -o - | FileCheck %s
+
+; CHECK-DAG: OpCapability Addresses
+; CHECK-DAG: OpName %[[#]] "foo"
+; CHECK-DAG: OpNop
+
+declare void @llvm.debugtrap()
+
+define spir_kernel void @foo(ptr addrspace(1) %a){
+entry:
+  %a.addr = alloca ptr addrspace(1), align 4
+  store ptr addrspace(1) %a, ptr %a.addr, align 4
+  call void @llvm.debugtrap()
+  ret void
+}

[MrSidims]

Seems like the PR collides with previous debug trap handling, as the failing test suggests, see

commit c538d5c8b2f1236f3bbba40c1abd15cf270550a5
Author: Vyacheslav Levytskyy <vyacheslav.levytskyy@intel.com>
Date:   Tue Oct 1 10:48:10 2024 +0200

    [SPIR-V] Discard some llvm intrinsics which we do not expect to actually represent code after lowering (#110233)

I don't have a strong opinion, which approach is better, but if we are aiming to merge this PR - ignore-llvm-intrinsic.ll test must be updated.

[github-actions]

@SubashBoopathi Congratulations on having your first Pull Request (PR) merged into the LLVM Project!

Your changes will be combined with recent changes from other authors, then tested by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR.

Please check whether problems have been caused by your change specifically, as the builds can include changes from many authors. It is not uncommon for your change to be included in a build that fails due to someone else's changes, or infrastructure issues.

How to do this, and the rest of the post-merge process, is covered in detail here.

If your change does cause a problem, it may be reverted, or you can revert it yourself. This is a normal part of LLVM development. You can fix your changes and open a new PR to merge them again.

If you don't get any reports, no action is required from you. Your changes are working as expected, well done!