[llvm] [SPIRV] Added lowering for the debugtrap intrinsic (PR #157442)

[Subash B via llvm-commits]

https://github.com/SubashBoopathi updated https://github.com/llvm/llvm-project/pull/157442

>From 09839aa9f6284f13ca69b2fde308cf43bafff45d Mon Sep 17 00:00:00 2001
From: Subash B <subash.boopathi at multicorewareinc.com>
Date: Thu, 21 Aug 2025 12:24:32 +0530
Subject: [PATCH 1/2] Added OpNop support for the debugtrap intrinsic

---
 .../lib/Target/SPIRV/SPIRVInstructionSelector.cpp | 14 +++++++++++++-
 .../CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll    | 15 +++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll

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
+}

>From 2579a4388319085745c90fe43b6e81aff074a2bf Mon Sep 17 00:00:00 2001
From: Subash B <subash.boopathi at multicorewareinc.com>
Date: Tue, 23 Sep 2025 14:00:45 +0530
Subject: [PATCH 2/2] Updated ignore-llvm-intrinsic.ll and updated the check
 directives of debug trap as suggested

---
 llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll         | 5 ++---
 .../CodeGen/SPIRV/llvm-intrinsics/ignore-llvm-intrinsic.ll   | 1 -
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll b/llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll
index 3f5fedf243cde..fd8cb9d7ff6f0 100644
--- a/llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll
+++ b/llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll
@@ -1,8 +1,7 @@
 ; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv32-unknown-unknown %s -o - | FileCheck %s
 
-; CHECK-DAG: OpCapability Addresses
-; CHECK-DAG: OpName %[[#]] "foo"
-; CHECK-DAG: OpNop
+; CHECK: OpNop
+; CHECK-NEXT: OpReturn
 
 declare void @llvm.debugtrap()
 
diff --git a/llvm/test/CodeGen/SPIRV/llvm-intrinsics/ignore-llvm-intrinsic.ll b/llvm/test/CodeGen/SPIRV/llvm-intrinsics/ignore-llvm-intrinsic.ll
index a15a80754cd60..b3ef6d6bbced9 100644
--- a/llvm/test/CodeGen/SPIRV/llvm-intrinsics/ignore-llvm-intrinsic.ll
+++ b/llvm/test/CodeGen/SPIRV/llvm-intrinsics/ignore-llvm-intrinsic.ll
@@ -11,7 +11,6 @@
 define spir_kernel void @foo(ptr %p) {
 entry:
   call void @llvm.trap()
-  call void @llvm.debugtrap()
   call void @llvm.ubsantrap(i8 100)
 
   %r1 = call ptr @llvm.invariant.start.p0(i64 1024, ptr %p)