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

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

Author: SubashBoopathi

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;
@@ -999,16 +1001,26 @@ 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,

llvm/test/CodeGen/SPIRV/llvm-intrinsics/debugtrap.ll

@@ -0,0 +1,14 @@
+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv32-unknown-unknown %s -o - | FileCheck %s
+
+; CHECK: OpNop
+; CHECK-NEXT: OpReturn
+
+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
+}

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)