AArch64: emit @llvm.debugtrap as `brk 0xf000` on all platforms

[t.p.northover]

Summary

It's useful for debuggers to be able to distinguish between a @llvm.trap (noreturn, so resuming would be a bad idea) and a @llvm.debugtrap (a call for attention, resumable).

This is implemented for Windows at the moment, where trap compiles to brk #1 but debugtrap to brk #0xf000. As far as I can tell there's no precedent on other platforms (GCC doesn't have __builtin_debugtrap) so I saw no reason to add unneeded platform divergence here and just removed the restriction.

[Gerolf]

Synced with the LLDB team. LGTM.

[t.p.northover]

Thanks Gerolf. Committed as 88464a55b4e

llvm/lib/Target/AArch64/AArch64FastISel.cpp

BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Opc), ResultReg)
       .addReg(SrcReg, getKillRegState(SrcRegIsKill));
     updateValueMap(II, ResultReg);
     return true;
   }
   case Intrinsic::trap:
     BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(AArch64::BRK))
         .addImm(1);
     return true;
-  case Intrinsic::debugtrap: {
-    if (Subtarget->isTargetWindows()) {
-      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(AArch64::BRK))
-          .addImm(0xF000);
-      return true;
-    }
-    break;
-  }
+  case Intrinsic::debugtrap:
 
   case Intrinsic::sqrt: {
     Type *RetTy = II->getCalledFunction()->getReturnType();
 
     MVT VT;
     if (!isTypeLegal(RetTy, VT))
       return false;
 

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

for (unsigned im = (unsigned)ISD::PRE_INC;
     setIndexedStoreAction(im, MVT::f64, Legal);
     setIndexedStoreAction(im, MVT::f32, Legal);
     setIndexedStoreAction(im, MVT::f16, Legal);
     setIndexedStoreAction(im, MVT::bf16, Legal);
   }
 
   // Trap.
   setOperationAction(ISD::TRAP, MVT::Other, Legal);
-  if (Subtarget->isTargetWindows())
-    setOperationAction(ISD::DEBUGTRAP, MVT::Other, Legal);
 
   // We combine OR nodes for bitfield operations.
   setTargetDAGCombine(ISD::OR);
   // Try to create BICs for vector ANDs.
   setTargetDAGCombine(ISD::AND);
 
   // Vector add and sub nodes may conceal a high-half opportunity.
   // Also, try to fold ADD into CSINC/CSINV..

llvm/lib/Target/AArch64/AArch64InstrInfo.td

 } // AddedComplexity = 20
 
 // To truncate, we can simply extract from a subregister.
 def : Pat<(i32 (trunc GPR64sp:$src)),
           (i32 (EXTRACT_SUBREG GPR64sp:$src, sub_32))>;
 
 // __builtin_trap() uses the BRK instruction on AArch64.
 def : Pat<(trap), (BRK 1)>;
-def : Pat<(debugtrap), (BRK 0xF000)>, Requires<[IsWindows]>;
+def : Pat<(debugtrap), (BRK 0xF000)>;
 
 // Multiply high patterns which multiply the lower subvector using smull/umull
 // and the upper subvector with smull2/umull2. Then shuffle the high the high
 // part of both results together.
 def : Pat<(v16i8 (mulhs V128:$Rn, V128:$Rm)),
           (UZP2v16i8
            (SMULLv8i8_v8i16 (EXTRACT_SUBREG V128:$Rn, dsub),
                             (EXTRACT_SUBREG V128:$Rm, dsub)),

llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp

bool AArch64InstructionSelector::selectIntrinsicWithSideEffects(
   // Select the instruction.
   switch (IntrinID) {
   default:
     return false;
   case Intrinsic::trap:
     MIRBuilder.buildInstr(AArch64::BRK, {}, {}).addImm(1);
     break;
   case Intrinsic::debugtrap:
-    if (!STI.isTargetWindows())
-      return false;
     MIRBuilder.buildInstr(AArch64::BRK, {}, {}).addImm(0xF000);
     break;
   }
 
   I.eraseFromParent();
   return true;
 }
 

llvm/test/CodeGen/AArch64/debugtrap.ll

 ; RUN: llc -mtriple=aarch64-windows %s -o -| FileCheck %s
 ; RUN: llc -mtriple=aarch64-windows -fast-isel %s -o - | FileCheck %s
 ; RUN: llc -mtriple=aarch64-windows -global-isel %s -o - | FileCheck %s
+; RUN: llc -mtriple=aarch64-linux-gnu %s -o -| FileCheck %s
+; RUN: llc -mtriple=arm64-apple-ios -global-isel %s -o - | FileCheck %s
+; RUN: llc -mtriple=arm64-apple-macosx -fast-isel %s -o - | FileCheck %s
 
 ; CHECK-LABEL: test1:
 ; CHECK: brk #0xf000
 define void @test1() noreturn nounwind  {
 entry:
   tail call void @llvm.debugtrap( )
   ret void
 }
 
 declare void @llvm.debugtrap() nounwind