[PATCH] D69390: [RISCV] Lower llvm.trap and llvm.debugtrap

[Sam Elliott via Phabricator via llvm-commits]

lenary created this revision.
lenary added reviewers: asb, luismarques.
Herald added subscribers: llvm-commits, pzheng, s.egerton, Jim, benna, psnobl, jocewei, PkmX, rkruppe, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, MaskRay, jrtc27, shiva0217, kito-cheng, niosHD, sabuasal, apazos, simoncook, johnrusso, rbar, hiraditya.
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Until this commit, these have lowered to a call to abort().

`llvm.trap()` now lowers to `unimp`, which should trap on all systems.

`llvm.debugtrap()` now lowers to `ebreak`, which is exactly what this
instruction is for.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D69390

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/lib/Target/RISCV/RISCVInstrInfo.td
  llvm/test/CodeGen/RISCV/intrinsics/trap.ll


Index: llvm/test/CodeGen/RISCV/intrinsics/trap.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/RISCV/intrinsics/trap.ll
@@ -0,0 +1,38 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV32I %s
+; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV64I %s
+
+; Verify that we lower @llvm.trap() and @llvm.debugtrap() correctly.
+
+declare void @llvm.trap()
+declare void @llvm.debugtrap()
+
+define void @test_trap() nounwind {
+; RV32I-LABEL: test_trap:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    unimp
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: test_trap:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    unimp
+; RV64I-NEXT:    ret
+  tail call void @llvm.trap()
+  ret void
+}
+
+define void @test_debugtrap() nounwind {
+; RV32I-LABEL: test_debugtrap:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    ebreak
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: test_debugtrap:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    ebreak
+; RV64I-NEXT:    ret
+  tail call void @llvm.debugtrap()
+  ret void
+}
Index: llvm/lib/Target/RISCV/RISCVInstrInfo.td
===================================================================
--- llvm/lib/Target/RISCV/RISCVInstrInfo.td
+++ llvm/lib/Target/RISCV/RISCVInstrInfo.td
@@ -1097,6 +1097,16 @@
 mayLoad = 0, mayStore = 0, hasNoSchedulingInfo = 1 in
 def ReadCycleWide : Pseudo<(outs GPR:$lo, GPR:$hi), (ins), [], "", "">;
 
+/// traps
+
+// We lower `trap` to `unimp`, as this causes a hard exception on nearly all
+// systems.
+def : Pat<(trap), (UNIMP)>;
+
+// We lower `debugtrap` to `ebreak`, as this will get the attention of the
+// debugger if possible.
+def : Pat<(debugtrap), (EBREAK)>;
+
 //===----------------------------------------------------------------------===//
 // Standard extensions
 //===----------------------------------------------------------------------===//
Index: llvm/lib/Target/RISCV/RISCVISelLowering.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -188,6 +188,9 @@
   setOperationAction(ISD::READCYCLECOUNTER, MVT::i64,
                      Subtarget.is64Bit() ? Legal : Custom);
 
+  setOperationAction(ISD::TRAP, MVT::Other, Legal);
+  setOperationAction(ISD::DEBUGTRAP, MVT::Other, Legal);
+
   if (Subtarget.hasStdExtA()) {
     setMaxAtomicSizeInBitsSupported(Subtarget.getXLen());
     setMinCmpXchgSizeInBits(32);


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