[DebugInfo][RemoveDIs] Don't convert debug-intrinsics to Unreachable

llvm/lib/Transforms/IPO/SCCP.cpp

@@ -236,11 +236,11 @@ static bool runIPSCCP(
     // nodes in executable blocks we found values for. The function's entry
     // block is not part of BlocksToErase, so we have to handle it separately.
     for (BasicBlock *BB : BlocksToErase) {
-      NumInstRemoved += changeToUnreachable(BB->getFirstNonPHI(),
+      NumInstRemoved += changeToUnreachable(BB->getFirstNonPHIOrDbg(),
                                             /*PreserveLCSSA=*/false, &DTU);
     }
     if (!Solver.isBlockExecutable(&F.front()))
-      NumInstRemoved += changeToUnreachable(F.front().getFirstNonPHI(),
+      NumInstRemoved += changeToUnreachable(F.front().getFirstNonPHIOrDbg(),
                                             /*PreserveLCSSA=*/false, &DTU);
 
     BasicBlock *NewUnreachableBB = nullptr;

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -2866,10 +2866,16 @@ void InstCombinerImpl::handleUnreachableFrom(
     }
     if (Inst.isEHPad() || Inst.getType()->isTokenTy())
       continue;
+    // RemoveDIs: erase debug-info on this instruction manually.
+    Inst.dropDbgValues();
     eraseInstFromFunction(Inst);
     MadeIRChange = true;
   }
 
+  // RemoveDIs: to match behaviour in dbg.value mode, drop debug-info on
+  // terminator too.
+  BB->getTerminator()->dropDbgValues();
+
   // Handle potentially dead successors.
   for (BasicBlock *Succ : successors(BB))
     addDeadEdge(BB, Succ, Worklist);

llvm/lib/Transforms/Utils/Local.cpp

@@ -2432,6 +2432,7 @@ unsigned llvm::changeToUnreachable(Instruction *I, bool PreserveLCSSA,
       Updates.push_back({DominatorTree::Delete, BB, UniqueSuccessor});
     DTU->applyUpdates(Updates);
   }
+  BB->flushTerminatorDbgValues();
   return NumInstrsRemoved;
 }
 
@@ -2585,9 +2586,9 @@ static bool markAliveBlocks(Function &F,
           // If we found a call to a no-return function, insert an unreachable
           // instruction after it.  Make sure there isn't *already* one there
           // though.
-          if (!isa<UnreachableInst>(CI->getNextNode())) {
+          if (!isa<UnreachableInst>(CI->getNextNonDebugInstruction())) {
             // Don't insert a call to llvm.trap right before the unreachable.
-            changeToUnreachable(CI->getNextNode(), false, DTU);
+            changeToUnreachable(CI->getNextNonDebugInstruction(), false, DTU);
             Changed = true;
           }
           break;

llvm/test/Transforms/InstCombine/assume.ll

@@ -2,6 +2,9 @@
 ; RUN: opt < %s -passes=instcombine -S | FileCheck --check-prefixes=CHECK,DEFAULT %s
 ; RUN: opt < %s -passes=instcombine --enable-knowledge-retention -S | FileCheck --check-prefixes=CHECK,BUNDLES %s
 
+; RUN: opt < %s -passes=instcombine -S --try-experimental-debuginfo-iterators | FileCheck --check-prefixes=CHECK,DEFAULT %s
+; RUN: opt < %s -passes=instcombine --enable-knowledge-retention -S --try-experimental-debuginfo-iterators | FileCheck --check-prefixes=CHECK,BUNDLES %s
+
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 

llvm/test/Transforms/InstCombine/unreachable-dbg-info-modified.ll

@@ -1,4 +1,5 @@
 ; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+; RUN: opt < %s -passes=instcombine -S --try-experimental-debuginfo-iterators | FileCheck %s
 
 ; When removing the llvm.dbg.value intrinsic in the unreachable block
 ; InstCombine would incorrectly return a false Modified status.

llvm/test/Transforms/SCCP/ipsccp-branch-unresolved-undef.ll

@@ -1,5 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature
 ; RUN: opt < %s -S -passes=ipsccp | FileCheck %s
+; RUN: opt < %s -S -passes=ipsccp --try-experimental-debuginfo-iterators | FileCheck %s
+;; Check that @patatino is optimised to "unreachable" given that it branches on
+;; undef. Check too that debug intrinsics have no effect on this.
 
 define void @main() {
 ; CHECK-LABEL: define {{[^@]+}}@main() {
@@ -17,7 +20,39 @@ define internal i1 @patatino(i1 %a) {
 ;
   br i1 %a, label %ontrue, label %onfalse
 ontrue:
+  call void @llvm.dbg.value(metadata i32 0, metadata !6, metadata !DIExpression()), !dbg !11
+  call void @llvm.dbg.value(metadata i32 1, metadata !9, metadata !DIExpression()), !dbg !11
   ret i1 false
 onfalse:
+  call void @llvm.dbg.value(metadata i32 0, metadata !6, metadata !DIExpression()), !dbg !11
+  call void @llvm.dbg.value(metadata i32 1, metadata !9, metadata !DIExpression()), !dbg !11
   ret i1 false
 }
+
+declare void @llvm.dbg.value(metadata, metadata, metadata) nounwind readnone
+
+!llvm.module.flags = !{!21}
+!llvm.dbg.cu = !{!2}
+
+!0 = distinct !DISubprogram(name: "foo", line: 2, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !2, file: !20, scope: !1, type: !3)
+!1 = !DIFile(filename: "b.c", directory: "/private/tmp")
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, producer: "clang", isOptimized: true, emissionKind: FullDebug, file: !20)
+!3 = !DISubroutineType(types: !4)
+!4 = !{!5}
+!5 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!6 = !DILocalVariable(name: "i", line: 2, arg: 1, scope: !0, file: !1, type: !5)
+!7 = !DILocation(line: 2, column: 13, scope: !0)
+!9 = !DILocalVariable(name: "k", line: 3, scope: !10, file: !1, type: !5)
+!10 = distinct !DILexicalBlock(line: 2, column: 16, file: !20, scope: !0)
+!11 = !DILocation(line: 3, column: 12, scope: !10)
+!12 = !DILocation(line: 4, column: 3, scope: !10)
+!13 = !DILocation(line: 5, column: 5, scope: !14)
+!14 = distinct !DILexicalBlock(line: 4, column: 10, file: !20, scope: !10)
+!15 = !DILocation(line: 6, column: 3, scope: !14)
+!16 = !DILocation(line: 7, column: 5, scope: !17)
+!17 = distinct !DILexicalBlock(line: 6, column: 10, file: !20, scope: !10)
+!18 = !DILocation(line: 8, column: 3, scope: !17)
+!19 = !DILocation(line: 9, column: 3, scope: !10)
+!20 = !DIFile(filename: "b.c", directory: "/private/tmp")
+!21 = !{i32 1, !"Debug Info Version", i32 3}
+

llvm/test/Transforms/SimplifyCFG/PR27615-simplify-cond-br.ll

@@ -1,6 +1,9 @@
 ; RUN: opt -S -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -strip-debug < %s | FileCheck %s
 ; RUN: opt -S -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s
 
+; RUN: opt -S -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -strip-debug < %s --try-experimental-debuginfo-iterators | FileCheck %s
+; RUN: opt -S -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s --try-experimental-debuginfo-iterators | FileCheck %s
+
 ; Test case for BUG-27615
 ; Test that simplify cond branch produce same result for debug and non-debug builds
 ; CHECK: select i1 %or.cond, i32 -1, i32 5

llvm/test/Transforms/SimplifyCFG/branch-fold-dbg.ll

@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s | FileCheck %s
+; RUN: opt -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S < %s --try-experimental-debuginfo-iterators | FileCheck %s
 
 %0 = type { ptr, ptr }
 

llvm/test/Transforms/SimplifyCFG/dbginfo.ll

@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
+; RUN: opt < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S --try-experimental-debuginfo-iterators | FileCheck %s
 
   %llvm.dbg.anchor.type = type { i32, i32 }
   %llvm.dbg.basictype.type = type { i32, ptr, ptr, ptr, i32, i64, i64, i64, i32, i32 }