[PATCH] D58035: [clang/DIVar] Emit flag for params that have unchanged values

[Djordje Todorovic via Phabricator via cfe-commits]

djtodoro updated this revision to Diff 200950.
djtodoro added a comment.

-Add `SPDefCache` to speed up the process
-Add additional assertions that will improve quality of the code


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D58035/new/

https://reviews.llvm.org/D58035

Files:
  lib/CodeGen/CGDebugInfo.cpp
  lib/CodeGen/CGDebugInfo.h


Index: lib/CodeGen/CGDebugInfo.h
===================================================================
--- lib/CodeGen/CGDebugInfo.h
+++ lib/CodeGen/CGDebugInfo.h
@@ -133,6 +133,10 @@
 
   llvm::DenseMap<const char *, llvm::TrackingMDRef> DIFileCache;
   llvm::DenseMap<const FunctionDecl *, llvm::TrackingMDRef> SPCache;
+  /// Cache function definitions relevant to use for parameters mutation
+  /// analysis.
+  llvm::DenseMap<const FunctionDecl *, llvm::TrackingMDRef> SPDefCache;
+  llvm::DenseMap<const ParmVarDecl *, llvm::TrackingMDRef> ParamCache;
   /// Cache declarations relevant to DW_TAG_imported_declarations (C++
   /// using declarations) that aren't covered by other more specific caches.
   llvm::DenseMap<const Decl *, llvm::TrackingMDRef> DeclCache;
Index: lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- lib/CodeGen/CGDebugInfo.cpp
+++ lib/CodeGen/CGDebugInfo.cpp
@@ -18,6 +18,7 @@
 #include "CodeGenFunction.h"
 #include "CodeGenModule.h"
 #include "ConstantEmitter.h"
+#include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclFriend.h"
 #include "clang/AST/DeclObjC.h"
@@ -3515,6 +3516,12 @@
   if (HasDecl && isa<FunctionDecl>(D))
     DeclCache[D->getCanonicalDecl()].reset(SP);
 
+  // We use the SPDefCache only in the case when the debug entry values option
+  // is set, in order to speed up parameters modification analysis.
+  if (CGM.getCodeGenOpts().EnableDebugEntryValues && HasDecl &&
+      isa<FunctionDecl>(D))
+    SPDefCache[cast<FunctionDecl>(D)].reset(SP);
+
   if (CGM.getCodeGenOpts().DwarfVersion >= 5) {
     // Starting with DWARF V5 method declarations are emitted as children of
     // the interface type.
@@ -3880,6 +3887,11 @@
                          llvm::DebugLoc::get(Line, Column, Scope, CurInlinedAt),
                          Builder.GetInsertBlock());
 
+  if (CGM.getCodeGenOpts().EnableDebugEntryValues && ArgNo) {
+    if (auto *PD = dyn_cast<ParmVarDecl>(VD))
+      ParamCache[PD].reset(D);
+  }
+
   return D;
 }
 
@@ -4454,6 +4466,29 @@
   TheCU->setDWOId(Signature);
 }
 
+/// Analyzes each function parameter to determine whether it is constant
+/// throughout the function body.
+static void analyzeParametersModification(
+    ASTContext &Ctx,
+    llvm::DenseMap<const FunctionDecl *, llvm::TrackingMDRef> &SPDefCache,
+    llvm::DenseMap<const ParmVarDecl *, llvm::TrackingMDRef> &ParamCache) {
+  for (auto &SP : SPDefCache) {
+    auto *FD = SP.first;
+    assert(FD->hasBody() && "Functions must have body here");
+    const Stmt *FuncBody = (*FD).getBody();
+    for (auto Parm : FD->parameters()) {
+      ExprMutationAnalyzer FuncAnalyzer(*FuncBody, Ctx);
+      if (FuncAnalyzer.isMutated(Parm))
+        continue;
+
+      auto I = ParamCache.find(Parm);
+      assert(I != ParamCache.end() && "Parameters should be already cached");
+      auto *DIParm = cast<llvm::DILocalVariable>(I->second);
+      DIParm->setIsNotModified();
+    }
+  }
+}
+
 void CGDebugInfo::finalize() {
   // Creating types might create further types - invalidating the current
   // element and the size(), so don't cache/reference them.
@@ -4526,6 +4561,10 @@
     if (auto MD = TypeCache[RT])
       DBuilder.retainType(cast<llvm::DIType>(MD));
 
+  if (CGM.getCodeGenOpts().EnableDebugEntryValues)
+    // This will be used to emit debug entry values.
+    analyzeParametersModification(CGM.getContext(), SPDefCache, ParamCache);
+
   DBuilder.finalize();
 }
 


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