[SelectionDAG][DebugInfo][RemoveDIs] Handle entry value variables in DPValues too

[jmorse]

This patch abstracts visitEntryValueDbgValue to deal with the substance of variable locations (Value, Var, Expr, DebugLoc) rather than how they're stored. That allows us to call it from handleDebugValue, which is similarly abstracted. This allows the entry-value behaviour (see the test) to be supported with non-instruction debug-info too!.

[llvmbot]

@llvm/pr-subscribers-backend-aarch64
@llvm/pr-subscribers-llvm-selectiondag

@llvm/pr-subscribers-debuginfo

Author: Jeremy Morse (jmorse)

Changes

This patch abstracts visitEntryValueDbgValue to deal with the substance of variable locations (Value, Var, Expr, DebugLoc) rather than how they're stored. That allows us to call it from handleDebugValue, which is similarly abstracted. This allows the entry-value behaviour (see the test) to be supported with non-instruction debug-info too!.

---

Full diff: https://github.com/llvm/llvm-project/pull/78726.diff

3 Files Affected:

• (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (+12-11)
• (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h (+3-1)
• (modified) llvm/test/CodeGen/AArch64/dbg-value-swift-async.ll (+4)

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 44c78a006656e0..a7dd23f78993fe 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1549,6 +1549,11 @@ bool SelectionDAGBuilder::handleDebugValue(ArrayRef<const Value *> Values,
                                            unsigned Order, bool IsVariadic) {
   if (Values.empty())
     return true;
+
+  // Filter EntryValue locations out early.
+  if (visitEntryValueDbgValue(Values, Var, Expr, DbgLoc))
+    return true;
+
   SmallVector<SDDbgOperand> LocationOps;
   SmallVector<SDNode *> Dependencies;
   for (const Value *V : Values) {
@@ -6023,14 +6028,14 @@ static const CallBase *FindPreallocatedCall(const Value *PreallocatedSetup) {
 /// If DI is a debug value with an EntryValue expression, lower it using the
 /// corresponding physical register of the associated Argument value
 /// (guaranteed to exist by the verifier).
-bool SelectionDAGBuilder::visitEntryValueDbgValue(const DbgValueInst &DI) {
-  DILocalVariable *Variable = DI.getVariable();
-  DIExpression *Expr = DI.getExpression();
-  if (!Expr->isEntryValue() || !hasSingleElement(DI.getValues()))
+bool SelectionDAGBuilder::visitEntryValueDbgValue(
+    ArrayRef<const Value *> Values, DILocalVariable *Variable,
+    DIExpression *Expr, DebugLoc DbgLoc) {
+  if (!Expr->isEntryValue() || !hasSingleElement(Values))
     return false;
 
   // These properties are guaranteed by the verifier.
-  Argument *Arg = cast<Argument>(DI.getValue(0));
+  const Argument *Arg = cast<Argument>(Values[0]);
   assert(Arg->hasAttribute(Attribute::AttrKind::SwiftAsync));
 
   auto ArgIt = FuncInfo.ValueMap.find(Arg);
@@ -6044,9 +6049,8 @@ bool SelectionDAGBuilder::visitEntryValueDbgValue(const DbgValueInst &DI) {
 
   for (auto [PhysReg, VirtReg] : FuncInfo.RegInfo->liveins())
     if (ArgVReg == VirtReg || ArgVReg == PhysReg) {
-      SDDbgValue *SDV =
-          DAG.getVRegDbgValue(Variable, Expr, PhysReg, false /*IsIndidrect*/,
-                              DI.getDebugLoc(), SDNodeOrder);
+      SDDbgValue *SDV = DAG.getVRegDbgValue(
+          Variable, Expr, PhysReg, false /*IsIndidrect*/, DbgLoc, SDNodeOrder);
       DAG.AddDbgValue(SDV, false /*treat as dbg.declare byval parameter*/);
       return true;
     }
@@ -6338,9 +6342,6 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
     DIExpression *Expression = DI.getExpression();
     dropDanglingDebugInfo(Variable, Expression);
 
-    if (visitEntryValueDbgValue(DI))
-      return;
-
     if (DI.isKillLocation()) {
       handleKillDebugValue(Variable, Expression, DI.getDebugLoc(), SDNodeOrder);
       return;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 6dcb8c816ad080..40e2f791f59e37 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -612,7 +612,9 @@ class SelectionDAGBuilder {
   void visitInlineAsm(const CallBase &Call,
                       const BasicBlock *EHPadBB = nullptr);
 
-  bool visitEntryValueDbgValue(const DbgValueInst &I);
+  bool visitEntryValueDbgValue(ArrayRef<const Value *> Values,
+                               DILocalVariable *Variable, DIExpression *Expr,
+                               DebugLoc DbgLoc);
   void visitIntrinsicCall(const CallInst &I, unsigned Intrinsic);
   void visitTargetIntrinsic(const CallInst &I, unsigned Intrinsic);
   void visitConstrainedFPIntrinsic(const ConstrainedFPIntrinsic &FPI);
diff --git a/llvm/test/CodeGen/AArch64/dbg-value-swift-async.ll b/llvm/test/CodeGen/AArch64/dbg-value-swift-async.ll
index e65f48825e8e34..4649fad5b2c2a4 100644
--- a/llvm/test/CodeGen/AArch64/dbg-value-swift-async.ll
+++ b/llvm/test/CodeGen/AArch64/dbg-value-swift-async.ll
@@ -2,6 +2,10 @@
 ; RUN: llc --mtriple="aarch64-" -O0 -fast-isel=false -global-isel=false -stop-after=finalize-isel %s -o - | FileCheck %s --check-prefix=AARCH
 ; RUN: llc --mtriple="aarch64-" -O0 -fast-isel -stop-after=finalize-isel %s -o - | FileCheck %s --check-prefix=AARCH
 
+; RUN: llc --mtriple="aarch64-" -O0 -global-isel -stop-after=irtranslator -verify-machineinstrs %s -o - --try-experimental-debuginfo-iterators | FileCheck %s --check-prefix=AARCH
+; RUN: llc --mtriple="aarch64-" -O0 -fast-isel=false -global-isel=false -stop-after=finalize-isel %s -o - --try-experimental-debuginfo-iterators | FileCheck %s --check-prefix=AARCH
+; RUN: llc --mtriple="aarch64-" -O0 -fast-isel -stop-after=finalize-isel %s -o - --try-experimental-debuginfo-iterators | FileCheck %s --check-prefix=AARCH
+
 ; AARCH-NOT:  DBG_VALUE
 ; AARCH:      DBG_VALUE $x22, $noreg, !{{.*}}, !DIExpression(DW_OP_LLVM_entry_value, 1)
 ; AARCH-NEXT: DBG_VALUE $x22, $noreg, !{{.*}}, !DIExpression(DW_OP_LLVM_entry_value, 1)

[felipepiovezan]

Behavior seems equivalent!