[clang] [RemoveDIs] Update Clang front end to handle DbgRecords (PR #84756)

[Orlando Cazalet-Hyams via cfe-commits]

https://github.com/OCHyams created https://github.com/llvm/llvm-project/pull/84756

This patch fixes problems that pop up when clang emits DbgRecords instead of debug intrinsics.

Note: this doesn't mean clang is emitting DbgRecords yet, because the modules it creates are still always in the old debug mode. That will come in a future patch.



>From 8b37020a48b8145ad9d7deb288b9f8a3ee3a9a9b Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Sat, 9 Mar 2024 13:10:05 +0000
Subject: [PATCH 1/2] clang: insertbefore non-debug for removeDIs stability

fixes debug-info-blocks.m in both modes
---
 clang/lib/CodeGen/CGBlocks.cpp             | 5 ++++-
 clang/test/CodeGenObjC/debug-info-blocks.m | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 0cbace7b7f7bbd..768b786c6426df 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -1540,7 +1540,10 @@ llvm::Function *CodeGenFunction::GenerateBlockFunction(
   llvm::BasicBlock *resume = Builder.GetInsertBlock();
 
   // Go back to the entry.
-  ++entry_ptr;
+  if (entry_ptr->getNextNonDebugInstruction())
+    entry_ptr = entry_ptr->getNextNonDebugInstruction()->getIterator();
+  else 
+    entry_ptr = entry->end();
   Builder.SetInsertPoint(entry, entry_ptr);
 
   // Emit debug information for all the DeclRefExprs.
diff --git a/clang/test/CodeGenObjC/debug-info-blocks.m b/clang/test/CodeGenObjC/debug-info-blocks.m
index 14b29f222fbe8e..59171da016da1e 100644
--- a/clang/test/CodeGenObjC/debug-info-blocks.m
+++ b/clang/test/CodeGenObjC/debug-info-blocks.m
@@ -5,8 +5,8 @@
 
 // CHECK: define {{.*}}_block_invoke
 // CHECK: store ptr %.block_descriptor, ptr %[[ALLOCA:block.addr]], align
-// CHECK-NEXT: call void @llvm.dbg.declare(metadata ptr %[[ALLOCA]], metadata ![[SELF:[0-9]+]], metadata !{{.*}})
 // CHECK-NEXT: call void @llvm.dbg.declare(metadata ptr %d, metadata ![[D:[0-9]+]], metadata !{{.*}})
+// CHECK-NEXT: call void @llvm.dbg.declare(metadata ptr %[[ALLOCA]], metadata ![[SELF:[0-9]+]], metadata !{{.*}})
 
 // Test that we do emit scope info for the helper functions, and that the
 // parameters to these functions are marked as artificial (so the debugger

>From efabe4b06f38aaf3aed8cf02c97f566652ba5f15 Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Sat, 9 Mar 2024 13:40:30 +0000
Subject: [PATCH 2/2] openmp update DbgRecords

Fixed OpenMP/debug_task_shared.c
---
 clang/lib/CodeGen/CGStmtOpenMP.cpp | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index 3fbd2e03eb61df..5c6a3b8e001730 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -4746,10 +4746,10 @@ void CodeGenFunction::EmitOMPTaskBasedDirective(
           if (CGF.CGM.getCodeGenOpts().hasReducedDebugInfo())
             (void)DI->EmitDeclareOfAutoVariable(SharedVar, ContextValue,
                                                 CGF.Builder, false);
-          llvm::Instruction &Last = CGF.Builder.GetInsertBlock()->back();
           // Get the call dbg.declare instruction we just created and update
           // its DIExpression to add offset to base address.
-          if (auto DDI = dyn_cast<llvm::DbgVariableIntrinsic>(&Last)) {
+          auto UpdateExpr = [](llvm::LLVMContext &Ctx, auto *DDI,
+                               unsigned Offset) {
             SmallVector<uint64_t, 8> Ops;
             // Add offset to the base address if non zero.
             if (Offset) {
@@ -4757,9 +4757,21 @@ void CodeGenFunction::EmitOMPTaskBasedDirective(
               Ops.push_back(Offset);
             }
             Ops.push_back(llvm::dwarf::DW_OP_deref);
-            auto &Ctx = DDI->getContext();
-            llvm::DIExpression *DIExpr = llvm::DIExpression::get(Ctx, Ops);
-            Last.setOperand(2, llvm::MetadataAsValue::get(Ctx, DIExpr));
+            DDI->setExpression(llvm::DIExpression::get(Ctx, Ops));
+          };
+          llvm::Instruction &Last = CGF.Builder.GetInsertBlock()->back();
+          if (auto DDI = dyn_cast<llvm::DbgVariableIntrinsic>(&Last))
+            UpdateExpr(DDI->getContext(), DDI, Offset);
+          // If we're emitting using the new debug info format into a block
+          // without a terminator, the record will be "trailing".
+          assert(!Last.isTerminator() && "unexpected terminator");
+          if (auto *Marker =
+                  CGF.Builder.GetInsertBlock()->getTrailingDPValues()) {
+            for (llvm::DPValue &DPV : llvm::reverse(
+                     llvm::DPValue::filter(Marker->getDbgValueRange()))) {
+              UpdateExpr(Last.getContext(), &DPV, Offset);
+              break;
+            }
           }
         }
       }