[llvm] [bolt] A better DIEBuilder for the llvm API change in #98905 (PR #99324)

[Pavel Labath via llvm-commits]

https://github.com/labath created https://github.com/llvm/llvm-project/pull/99324

The caller (cloneAttribute) already switches on the reference type. By aligning the cases with the retrieval functions, we can avoid branching twice.

>From 8f4287e1cc7ffc399c5aff464907edd299ea002f Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel at labath.sk>
Date: Wed, 17 Jul 2024 15:05:15 +0200
Subject: [PATCH] [bolt] A better DIEBuilder for the llvm API change in #98905

The caller (cloneAttribute) already switches on the reference type. By
aligning the cases with the retrieval functions, we can avoid branching
twice.
---
 bolt/include/bolt/Core/DIEBuilder.h | 12 ++------
 bolt/lib/Core/DIEBuilder.cpp        | 43 +++++++----------------------
 2 files changed, 12 insertions(+), 43 deletions(-)

diff --git a/bolt/include/bolt/Core/DIEBuilder.h b/bolt/include/bolt/Core/DIEBuilder.h
index c562373c718ba..0b840c142ed81 100644
--- a/bolt/include/bolt/Core/DIEBuilder.h
+++ b/bolt/include/bolt/Core/DIEBuilder.h
@@ -135,13 +135,6 @@ class DIEBuilder {
 
   /// Returns current state of the DIEBuilder
   State &getState() { return *BuilderState.get(); }
-  /// Resolve the reference in DIE, if target is not loaded into IR,
-  /// pre-allocate it. \p RefCU will be updated to the Unit specific by \p
-  /// RefValue.
-  DWARFDie resolveDIEReference(
-      const DWARFFormValue &RefValue,
-      const DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
-      DWARFUnit *&RefCU, DWARFDebugInfoEntry &DwarfDebugInfoEntry);
 
   /// Resolve the reference in DIE, if target is not loaded into IR,
   /// pre-allocate it. \p RefCU will be updated to the Unit specific by \p
@@ -165,10 +158,9 @@ class DIEBuilder {
       const DWARFFormValue &Val);
 
   /// Clone an attribute in reference format.
-  void cloneDieReferenceAttribute(
+  void cloneDieOffsetReferenceAttribute(
       DIE &Die, const DWARFUnit &U, const DWARFDie &InputDIE,
-      const DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
-      const DWARFFormValue &Val);
+      const DWARFAbbreviationDeclaration::AttributeSpec AttrSpec, uint64_t Ref);
 
   /// Clone an attribute in block format.
   void cloneBlockAttribute(
diff --git a/bolt/lib/Core/DIEBuilder.cpp b/bolt/lib/Core/DIEBuilder.cpp
index 7815a305c0518..b0f550fd77318 100644
--- a/bolt/lib/Core/DIEBuilder.cpp
+++ b/bolt/lib/Core/DIEBuilder.cpp
@@ -551,25 +551,6 @@ void DIEBuilder::finish() {
   updateReferences();
 }
 
-DWARFDie DIEBuilder::resolveDIEReference(
-    const DWARFFormValue &RefValue,
-    const DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
-    DWARFUnit *&RefCU, DWARFDebugInfoEntry &DwarfDebugInfoEntry) {
-  assert(RefValue.isFormClass(DWARFFormValue::FC_Reference));
-  uint64_t RefOffset;
-  if (std::optional<uint64_t> Off = RefValue.getAsRelativeReference()) {
-    RefOffset = RefValue.getUnit()->getOffset() + *Off;
-  } else if (Off = RefValue.getAsDebugInfoReference(); Off) {
-    RefOffset = *Off;
-  } else {
-    BC.errs()
-        << "BOLT-WARNING: [internal-dwarf-error]: unsupported reference type: "
-        << FormEncodingString(RefValue.getForm()) << ".\n";
-    return DWARFDie();
-  }
-  return resolveDIEReference(AttrSpec, RefOffset, RefCU, DwarfDebugInfoEntry);
-}
-
 DWARFDie DIEBuilder::resolveDIEReference(
     const DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
     const uint64_t RefOffset, DWARFUnit *&RefCU,
@@ -613,23 +594,14 @@ DWARFDie DIEBuilder::resolveDIEReference(
   return DWARFDie();
 }
 
-void DIEBuilder::cloneDieReferenceAttribute(
+void DIEBuilder::cloneDieOffsetReferenceAttribute(
     DIE &Die, const DWARFUnit &U, const DWARFDie &InputDIE,
-    const DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
-    const DWARFFormValue &Val) {
-  uint64_t Ref;
-  if (std::optional<uint64_t> Off = Val.getAsRelativeReference())
-    Ref = Val.getUnit()->getOffset() + *Off;
-  else if (Off = Val.getAsDebugInfoReference(); Off)
-    Ref = *Off;
-  else
-    return;
-
+    const DWARFAbbreviationDeclaration::AttributeSpec AttrSpec, uint64_t Ref) {
   DIE *NewRefDie = nullptr;
   DWARFUnit *RefUnit = nullptr;
 
   DWARFDebugInfoEntry DDIEntry;
-  const DWARFDie RefDie = resolveDIEReference(Val, AttrSpec, RefUnit, DDIEntry);
+  const DWARFDie RefDie = resolveDIEReference(AttrSpec, Ref, RefUnit, DDIEntry);
 
   if (!RefDie)
     return;
@@ -834,7 +806,7 @@ void DIEBuilder::cloneAddressAttribute(
 void DIEBuilder::cloneRefsigAttribute(
     DIE &Die, DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
     const DWARFFormValue &Val) {
-  const std::optional<uint64_t> SigVal = Val.getRawUValue();
+  const std::optional<uint64_t> SigVal = Val.getAsSignatureReference();
   Die.addValue(getState().DIEAlloc, AttrSpec.Attr, dwarf::DW_FORM_ref_sig8,
                DIEInteger(*SigVal));
 }
@@ -902,11 +874,16 @@ void DIEBuilder::cloneAttribute(
     cloneStringAttribute(Die, U, AttrSpec, Val);
     break;
   case dwarf::DW_FORM_ref_addr:
+    cloneDieOffsetReferenceAttribute(Die, U, InputDIE, AttrSpec,
+                                     *Val.getAsDebugInfoReference());
+    break;
   case dwarf::DW_FORM_ref1:
   case dwarf::DW_FORM_ref2:
   case dwarf::DW_FORM_ref4:
   case dwarf::DW_FORM_ref8:
-    cloneDieReferenceAttribute(Die, U, InputDIE, AttrSpec, Val);
+    cloneDieOffsetReferenceAttribute(Die, U, InputDIE, AttrSpec,
+                                     Val.getUnit()->getOffset() +
+                                         *Val.getAsRelativeReference());
     break;
   case dwarf::DW_FORM_block:
   case dwarf::DW_FORM_block1: