[SelectionDAG] Add debug info salvaging for bitcast operations

This is needed to retain debug info for 64 bit kernel parameters.

Change-Id: Id3914345ef7a434355f36e45d3ea0bf6c7ae29aa

Author: epilk

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -15821,8 +15821,10 @@ SDValue DAGCombiner::visitBITCAST(SDNode *N) {
   }
 
   // (conv (conv x, t1), t2) -> (conv x, t2)
-  if (N0.getOpcode() == ISD::BITCAST)
+  if (N0.getOpcode() == ISD::BITCAST) {
+    DAG.salvageDebugInfo(*N0.getNode());
     return DAG.getBitcast(VT, N0.getOperand(0));
+  }
 
   // fold (conv (logicop (conv x), (c))) -> (logicop x, (conv c))
   // iff the current bitwise logicop type isn't legal

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -11577,6 +11577,35 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) {
                  dbgs() << " into " << *DbgExpression << '\n');
       break;
     }
+    case ISD::BITCAST: {
+      DIExpression *Expr = DV->getExpression();
+      if (Expr->holdsOldElements())
+        break;
+
+      SDValue N0 = N.getOperand(0);
+      auto NewLocOps = DV->copyLocationOps();
+      bool Changed = false;
+      for (size_t i = 0; i < NewLocOps.size(); ++i) {
+        if (NewLocOps[i].getKind() != SDDbgOperand::SDNODE ||
+            NewLocOps[i].getSDNode() != &N)
+          continue;
+        NewLocOps[i] = SDDbgOperand::fromNode(N0.getNode(), N0.getResNo());
+        Changed = true;
+      }
+      assert(Changed && "Salvage target doesn't use N");
+      (void)Changed;
+
+      SDDbgValue *Clone =
+          getDbgValueList(DV->getVariable(), Expr, NewLocOps,
+                          DV->getAdditionalDependencies(), DV->isIndirect(),
+                          DV->getDebugLoc(), DV->getOrder(), DV->isVariadic());
+      ClonedDVs.push_back(Clone);
+      DV->setIsInvalidated();
+      DV->setIsEmitted();
+      LLVM_DEBUG(dbgs() << "SALVAGE: Rewriting"; N0.getNode()->dumprFull(this);
+                 dbgs() << " into " << *Expr << '\n');
+      break;
+    }
     }
   }
 

llvm/test/DebugInfo/AMDGPU/heterogeneous-dwarf-diop-diexpression-args.ll

@@ -0,0 +1,99 @@
+; RUN: llc -O1 -mcpu=gfx1030 -mtriple=amdgcn-amd-amdhsa -filetype=obj -o - < %s | llvm-dwarfdump --debug-info - | FileCheck %s
+
+;; Verify that we produce valid debug locations for parameters of various types.
+
+@glob_ptr = global ptr addrspace(1) null
+
+; CHECK-LABEL: DW_AT_name ("int32_k")
+define amdgpu_kernel void @int32_k(i32 %a) !dbg !9 {
+  ; CHECK: DW_AT_location
+  ; CHECK-NEXT: [0x{{[0-9a-z]+}}, 0x{{[0-9a-z]+}}): DW_OP_regx SGPR{{[0-9]+}})
+  tail call void @llvm.dbg.value(metadata i32 %a, metadata !12, metadata !DIExpression(DIOpArg(0, i32))), !dbg !14
+  store i32 %a, ptr @glob_ptr, align 4, !dbg !14
+  ret void, !dbg !15
+}
+
+; CHECK-LABEL: DW_AT_name ("int64_k")
+define amdgpu_kernel void @int64_k(i64 %a) !dbg !31 {
+  ; CHECK: DW_AT_location
+  ; CHECK-NEXT: DW_OP_regx SGPR{{[0-9a-z]+}}, DW_OP_piece 0x4, DW_OP_regx SGPR{{[0-9a-z]+}}, DW_OP_piece 0x4, DW_OP_LLVM_user DW_OP_LLVM_piece_end
+  tail call void @llvm.dbg.value(metadata i64 %a, metadata !32, metadata !DIExpression(DIOpArg(0, i64))), !dbg !33
+  store i64 %a, ptr @glob_ptr, align 8, !dbg !33
+  ret void, !dbg !33
+}
+
+; CHECK-LABEL: DW_AT_name ("as1_ptr")
+define void @as1_ptr(ptr addrspace(1) %ptr) !dbg !16 {
+  ; CHECK: DW_AT_location
+  ; CHECK-NEXT: [0x{{[0-9a-z]+}}, 0x{{[0-9a-z]+}}): DW_OP_regx 0x{{[0-9a-z]+}}, DW_OP_piece 0x4, DW_OP_regx 0x{{[0-9a-z]+}}, DW_OP_piece 0x4)
+  tail call void @llvm.dbg.value(metadata ptr addrspace(1) %ptr, metadata !17, metadata !DIExpression(DIOpArg(0, ptr addrspace(1)))), !dbg !20
+  store ptr addrspace(1) %ptr, ptr @glob_ptr, align 8, !dbg !20
+  ret void, !dbg !20
+}
+
+; CHECK-LABEL: DW_AT_name ("int64")
+define void @int64(i64 %a) !dbg !21 {
+  ; CHECK: DW_AT_location
+  ; CHECK-NEXT: [0x{{[0-9a-z]+}}, 0x{{[0-9a-z]+}}): DW_OP_regx 0x{{[0-9a-z]+}}, DW_OP_piece 0x4, DW_OP_regx 0x{{[0-9a-z]+}}, DW_OP_piece 0x4)
+  tail call void @llvm.dbg.value(metadata i64 %a, metadata !22, metadata !DIExpression(DIOpArg(0, i64))), !dbg !23
+  store i64 %a, ptr @glob_ptr, align 8, !dbg !23
+  ret void, !dbg !24
+}
+
+; CHECK-LABEL: DW_AT_name ("int32")
+define void @int32(i32 %a) !dbg !25 {
+  ; CHECK: DW_AT_location (DW_OP_regx 0x{{[0-9a-z]+}})
+  tail call void @llvm.dbg.value(metadata i32 %a, metadata !26, metadata !DIExpression(DIOpArg(0, i32))), !dbg !27
+  store i32 %a, ptr @glob_ptr, align 4, !dbg !27
+  ret void, !dbg !27
+}
+
+; CHECK-LABEL: DW_AT_name ("gen_ptr")
+define void @gen_ptr(ptr %ptr) !dbg !28 {
+  ; CHECK: DW_AT_location
+  ; CHECK-NEXT: [0x{{[0-9a-z]+}}, 0x{{[0-9a-z]+}}): DW_OP_regx 0x{{[0-9a-z]+}}, DW_OP_piece 0x4, DW_OP_regx 0x{{[0-9a-z]+}}, DW_OP_piece 0x4)
+  tail call void @llvm.dbg.value(metadata ptr %ptr, metadata !29, metadata !DIExpression(DIOpArg(0, ptr))), !dbg !30
+  store ptr %ptr, ptr @glob_ptr, align 8, !dbg !30
+  ret void, !dbg !30
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7}
+!llvm.ident = !{!8}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 19.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "t.cpp", directory: "/")
+!2 = !{i32 1, !"amdhsa_code_object_version", i32 500}
+!3 = !{i32 7, !"Dwarf Version", i32 5}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{i32 8, !"PIC Level", i32 2}
+!7 = !{i32 7, !"frame-pointer", i32 2}
+!8 = !{!"clang version 19.0.0"}
+!9 = distinct !DISubprogram(name: "int32_k", linkageName: "int32_k", scope: !1, file: !1, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
+!10 = !DISubroutineType(types: !11)
+!11 = !{}
+!12 = !DILocalVariable(name: "i32", arg: 1, scope: !9, file: !1, type: !13)
+!13 = !DIBasicType(name: "i32", size: 32, encoding: DW_ATE_signed)
+!14 = !DILocation(line: 1, column: 1, scope: !9)
+!15 = !DILocation(line: 2, column: 1, scope: !9)
+!16 = distinct !DISubprogram(name: "as1_ptr", linkageName: "as1_ptr", scope: !1, file: !1, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
+!17 = !DILocalVariable(name: "ptr", arg: 1, scope: !16, file: !1, line: 1, type: !18)
+!18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !19, size: 64)
+!19 = !DIBasicType(name: "i64", size: 64, encoding: DW_ATE_signed)
+!20 = !DILocation(line: 1, column: 1, scope: !16)
+!21 = distinct !DISubprogram(name: "int64", linkageName: "int64", scope: !1, file: !1, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
+!22 = !DILocalVariable(name: "i64", arg: 1, scope: !21, file: !1, type: !19)
+!23 = !DILocation(line: 1, column: 1, scope: !21)
+!24 = !DILocation(line: 2, column: 1, scope: !21)
+!25 = distinct !DISubprogram(name: "int32", linkageName: "int32", scope: !1, file: !1, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
+!26 = !DILocalVariable(name: "i32", arg: 1, scope: !25, file: !1, type: !13)
+!27 = !DILocation(line: 1, column: 1, scope: !25)
+!28 = distinct !DISubprogram(name: "gen_ptr", linkageName: "gen_ptr", scope: !1, file: !1, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
+!29 = !DILocalVariable(name: "ptr", arg: 1, scope: !28, file: !1, type: !18)
+!30 = !DILocation(line: 1, column: 1, scope: !28)
+!31 = distinct !DISubprogram(name: "int64_k", linkageName: "int64_k", scope: !1, file: !1, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
+!32 = !DILocalVariable(name: "i32", arg: 1, scope: !31, file: !1, type: !19)
+!33 = !DILocation(line: 1, column: 1, scope: !31)