[llvm-branch-commits] [llvm] 29077ae - [IRBuilder] Generalize debug loc handling for arbitrary metadata.

[Florian Hahn via llvm-branch-commits]

Author: Florian Hahn
Date: 2020-12-17T13:27:43Z
New Revision: 29077ae860bcf3c9e9f2ce67ca7dfe691b6fa148

URL: https://github.com/llvm/llvm-project/commit/29077ae860bcf3c9e9f2ce67ca7dfe691b6fa148
DIFF: https://github.com/llvm/llvm-project/commit/29077ae860bcf3c9e9f2ce67ca7dfe691b6fa148.diff

LOG: [IRBuilder] Generalize debug loc handling for arbitrary metadata.

This patch extends IRBuilder to allow adding/preserving arbitrary
metadata on created instructions.

Instead of using references to specific metadata nodes (like DebugLoc),
IRbuilder now keeps a vector of (metadata kind, MDNode *) pairs, which
are added to each created instruction.

The patch itself is a NFC and only moves the existing debug location
handling over to the new system. In a follow-up patch it will be used to
preserve !annotation metadata besides !dbg.

The current approach requires iterating over MetadataToCopy to avoid
adding duplicates, but given that the number of metadata kinds to
copy/preserve is going to be very small initially (0, 1 (for !dbg) or 2
(!dbg and !annotation)) that should not matter.

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D93400

Added: 
    

Modified: 
    llvm/include/llvm/IR/IRBuilder.h
    llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
    llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/IR/IRBuilder.h b/llvm/include/llvm/IR/IRBuilder.h
index 0191a2a6d28b..56005b26a538 100644
--- a/llvm/include/llvm/IR/IRBuilder.h
+++ b/llvm/include/llvm/IR/IRBuilder.h
@@ -17,6 +17,7 @@
 #include "llvm-c/Types.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/None.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/IR/BasicBlock.h"
@@ -24,6 +25,7 @@
 #include "llvm/IR/ConstantFolder.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/DebugLoc.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
@@ -91,7 +93,28 @@ class IRBuilderCallbackInserter : public IRBuilderDefaultInserter {
 
 /// Common base class shared among various IRBuilders.
 class IRBuilderBase {
-  DebugLoc CurDbgLocation;
+  /// Pairs of (metadata kind, MDNode *) that should be added to all newly
+  /// created instructions, like !dbg metadata.
+  SmallVector<std::pair<unsigned, MDNode *>, 2> MetadataToCopy;
+
+  /// Add or update the an entry (Kind, MD) to MetadataToCopy, if \p MD is not
+  /// null. If \p MD is null, remove the entry with \p Kind.
+  void AddOrRemoveMetadataToCopy(unsigned Kind, MDNode *MD) {
+    if (!MD) {
+      erase_if(MetadataToCopy, [Kind](const std::pair<unsigned, MDNode *> &KV) {
+        return KV.first == Kind;
+      });
+      return;
+    }
+
+    for (auto &KV : MetadataToCopy)
+      if (KV.first == Kind) {
+        KV.second = MD;
+        return;
+      }
+
+    MetadataToCopy.emplace_back(Kind, MD);
+  }
 
 protected:
   BasicBlock *BB;
@@ -125,7 +148,7 @@ class IRBuilderBase {
   template<typename InstTy>
   InstTy *Insert(InstTy *I, const Twine &Name = "") const {
     Inserter.InsertHelper(I, Name, BB, InsertPt);
-    SetInstDebugLocation(I);
+    AddMetadataToInst(I);
     return I;
   }
 
@@ -182,16 +205,42 @@ class IRBuilderBase {
   }
 
   /// Set location information used by debugging information.
-  void SetCurrentDebugLocation(DebugLoc L) { CurDbgLocation = std::move(L); }
+  void SetCurrentDebugLocation(DebugLoc L) {
+    AddOrRemoveMetadataToCopy(LLVMContext::MD_dbg, L.getAsMDNode());
+  }
+
+  /// Collect metadata with IDs \p MetadataKinds from \p Src which should be
+  /// added to all created instructions. Entries present in MedataDataToCopy but
+  /// not on \p Src will be dropped from MetadataToCopy.
+  void CollectMetadataToCopy(Instruction *Src,
+                             ArrayRef<unsigned> MetadataKinds) {
+    for (unsigned K : MetadataKinds)
+      AddOrRemoveMetadataToCopy(K, Src->getMetadata(K));
+  }
 
   /// Get location information used by debugging information.
-  const DebugLoc &getCurrentDebugLocation() const { return CurDbgLocation; }
+  DebugLoc getCurrentDebugLocation() const {
+    for (auto &KV : MetadataToCopy)
+      if (KV.first == LLVMContext::MD_dbg)
+        return {cast<DILocation>(KV.second)};
+
+    return {};
+  }
 
   /// If this builder has a current debug location, set it on the
   /// specified instruction.
   void SetInstDebugLocation(Instruction *I) const {
-    if (CurDbgLocation)
-      I->setDebugLoc(CurDbgLocation);
+    for (const auto &KV : MetadataToCopy)
+      if (KV.first == LLVMContext::MD_dbg) {
+        I->setDebugLoc(DebugLoc(KV.second));
+        return;
+      }
+  }
+
+  /// Add all entries in MetadataToCopy to \p I.
+  void AddMetadataToInst(Instruction *I) const {
+    for (auto &KV : MetadataToCopy)
+      I->setMetadata(KV.first, KV.second);
   }
 
   /// Get the return type of the current function that we're emitting

diff  --git a/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h b/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
index c672691838cf..67a406d2492b 100644
--- a/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
+++ b/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
@@ -352,7 +352,7 @@ class SCEVExpander : public SCEVVisitor<SCEVExpander, Value *> {
   }
 
   /// Get location information used by debugging information.
-  const DebugLoc &getCurrentDebugLocation() const {
+  DebugLoc getCurrentDebugLocation() const {
     return Builder.getCurrentDebugLocation();
   }
 

diff  --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 770d58b31664..872ef5772c2a 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3678,7 +3678,7 @@ bool InstCombinerImpl::run() {
 
     // Now that we have an instruction, try combining it to simplify it.
     Builder.SetInsertPoint(I);
-    Builder.SetCurrentDebugLocation(I->getDebugLoc());
+    Builder.CollectMetadataToCopy(I, {LLVMContext::MD_dbg});
 
 #ifndef NDEBUG
     std::string OrigI;