When stripping debug info, also rewrite @llvm.debugtrap to @llvm.trap.

[jfb]

lgtm, leaving open it see if there are other comments.

[echristo]

Seems odd, why not just remove it since it's supposed to be "for a debugger"

(For the record, I have no dog in this show, just asking about the logic.)

-eric

[DiamondLovesYou]

In D10349#190766, @echristo wrote:

Seems odd, why not just remove it since it's supposed to be "for a debugger"

(For the record, I have no dog in this show, just asking about the logic.)

-eric

Sorry 'bout the delay in getting back to you.

Honestly, I hadn't thought of that. Now that I have, I'd say rewriting to @llvm.trap is better because (I speculate) it would be the least surprising behaviour to developers.

Richard Diamond

lib/IR/DebugInfo.cpp

if (Function *DbgVal = M.getFunction("llvm.dbg.value")) {
     while (!DbgVal->use_empty()) {
       CallInst *CI = cast<CallInst>(DbgVal->user_back());
       CI->eraseFromParent();
     }
     DbgVal->eraseFromParent();
     Changed = true;
   }
 
+  // Rewrite `@llvm.debugtrap` to `@llvm.trap`.
+  if (Function *DbgTrap = M.getFunction("llvm.debugtrap")) {
+    Function* Trap = Intrinsic::getDeclaration(&M, Intrinsic::trap);
+    while (!DbgTrap->use_empty()) {
+      CallInst *CI = cast<CallInst>(DbgTrap->user_back());
+      CallInst::Create(Trap, None, "", CI);
+      CI->eraseFromParent();
+    }
+    DbgTrap->eraseFromParent();
+    Changed = true;
+  }
+
   for (Module::named_metadata_iterator NMI = M.named_metadata_begin(),
          NME = M.named_metadata_end(); NMI != NME;) {
     NamedMDNode *NMD = NMI;
     ++NMI;
     if (NMD->getName().startswith("llvm.dbg.")) {
       NMD->eraseFromParent();
       Changed = true;
     }

test/CodeGen/X86/trap.ll

 ; PS4-LABEL: test1:
 ; PS4: int     $65
 define i32 @test1() noreturn nounwind  {
 entry:
   tail call void @llvm.debugtrap( )
   unreachable
 }
 
-declare void @llvm.trap() nounwind 
-declare void @llvm.debugtrap() nounwind 
+declare void @llvm.trap() nounwind
+declare void @llvm.debugtrap() nounwind
 
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 2, !"Debug Info Version", i32 3}

test/DebugInfo/rewrite-debug-trap.ll

+; RUN: opt -strip-debug < %s -S | FileCheck %s
+
+; CHECK-NOT: llvm.debugtrap
+
+declare void @llvm.debugtrap()
+
+; CHECK-LABEL: @call_debugtrap
+define void @call_debugtrap() {
+entry:
+; CHECK: call void @llvm.trap()
+  call void @llvm.debugtrap()
+  ret void
+}