[Utils] Salvage the debug info of DCE'ed ‘and’ instructions

[djtodoro]

Summary

Preserve debug info from a dead ‘and’ instruction with a constant.

[vsk]

LGTM.

As a follow-up, I think we should move the dce-and/dce-or tests to test/Transforms/InstCombine/debuginfo-variables.ll. I can send in patch later today to do that.

[vsk]

Actually, would you mind rebasing and moving the test into 'test/Transforms/InstCombine/debuginfo-variables.ll' before landing this? It'd be a bit easier to understand that way and we'll avoid an extra move commit.

[djtodoro]

@vsk Thanks for your comments and review! D43207 LGTM. I'll do that way.

[vsk]

Perfect, thanks!

lib/CodeGen/AsmPrinter/DwarfExpression.cpp

case dwarf::DW_OP_plus_uconst:
       emitUnsigned(Op->getArg(0));
       break;
     case dwarf::DW_OP_plus:
     case dwarf::DW_OP_minus:
     case dwarf::DW_OP_mul:
     case dwarf::DW_OP_div:
     case dwarf::DW_OP_mod:
     case dwarf::DW_OP_or:
+    case dwarf::DW_OP_and:
     case dwarf::DW_OP_xor:
     case dwarf::DW_OP_shl:
     case dwarf::DW_OP_shr:
     case dwarf::DW_OP_shra:
       emitOp(Op->getOp());
       break;
     case dwarf::DW_OP_deref:
       assert(LocationKind != Register);

lib/IR/DebugInfoMetadata.cpp

for (auto I = expr_op_begin(), E = expr_op_end(); I != E; ++I) {
     case dwarf::DW_OP_constu:
     case dwarf::DW_OP_plus_uconst:
     case dwarf::DW_OP_plus:
     case dwarf::DW_OP_minus:
     case dwarf::DW_OP_mul:
     case dwarf::DW_OP_div:
     case dwarf::DW_OP_mod:
     case dwarf::DW_OP_or:
+    case dwarf::DW_OP_and:
     case dwarf::DW_OP_xor:
     case dwarf::DW_OP_shl:
     case dwarf::DW_OP_shr:
     case dwarf::DW_OP_shra:
     case dwarf::DW_OP_deref:
     case dwarf::DW_OP_xderef:
       break;
     }

lib/Transforms/Utils/Local.cpp

for (auto *DII : DbgUsers) {
         applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_div});
         break;
       case Instruction::SRem:
         applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_mod});
         break;
       case Instruction::Or:
         applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_or});
         break;
+      case Instruction::And:
+        applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_and});
+        break;
       case Instruction::Xor:
         applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_xor});
         break;
       case Instruction::Shl:
         applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_shl});
         break;
       case Instruction::LShr:
         applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_shr});

test/Transforms/InstCombine/debuginfo-variables.ll

 
 define void @test_ptrtoint(i64* %P) {
 ; CHECK-LABEL: @test_ptrtoint
 ; CHECK-NEXT:  call void @llvm.dbg.value(metadata i64* %P, metadata !67, metadata !DIExpression()), !dbg !68
   %1 = ptrtoint i64* %P to i64
   ret void
 }
 
+define void @test_and(i64 %A) {
+; CHECK-LABEL: @test_and(
+; CHECK-NEXT:  call void @llvm.dbg.value(metadata i64 %A, metadata !72, metadata !DIExpression(DW_OP_constu, 256, DW_OP_and, DW_OP_stack_value)), !dbg !73
+  %1 = and i64 %A, 256
+  ret void
+}
+
 ; CHECK: !8 = !DILocalVariable(name: "1", scope: !5, file: !1, line: 1, type: !9)
 ; CHECK: !10 = !DILocalVariable(name: "2", scope: !5, file: !1, line: 2, type: !11)
 ; CHECK: !12 = !DILocation(line: 2, column: 1, scope: !5)
 ; CHECK: !13 = !DILocation(line: 1, column: 1, scope: !5)
 
 ; CHECK: !17 = !DILocalVariable(name: "3", scope: !15, file: !1, line: 4, type: !11)
 ; CHECK: !18 = !DILocation(line: 4, column: 1, scope: !15)
 

 ; CHECK: !57 = !DILocalVariable(name: "11", scope: !55, file: !1, line: 20, type: !11)
 ; CHECK: !58 = !DILocation(line: 20, column: 1, scope: !55)
 
 ; CHECK: !62 = !DILocalVariable(name: "12", scope: !60, file: !1, line: 22, type: !11)
 ; CHECK: !63 = !DILocation(line: 22, column: 1, scope: !60)
 
 ; CHECK: !67 = !DILocalVariable(name: "13", scope: !65, file: !1, line: 24, type: !11)
 ; CHECK: !68 = !DILocation(line: 24, column: 1, scope: !65)
+
+; CHECK: !72 = !DILocalVariable(name: "14", scope: !70, file: !1, line: 26, type: !11)
+; CHECK: !73 = !DILocation(line: 26, column: 1, scope: !70)