[llvm] 70fdbf3 - Adding DiBuilder interface for assumed length strings

YASHASVI KHATAVKAR via llvm-commits llvm-commits at lists.llvm.org
Fri Feb 11 11:40:28 PST 2022


Author: YASHASVI KHATAVKAR
Date: 2022-02-11T14:40:02-05:00
New Revision: 70fdbf35de1c37a22a5321ed7d7d2c190d788549

URL: https://github.com/llvm/llvm-project/commit/70fdbf35de1c37a22a5321ed7d7d2c190d788549
DIFF: https://github.com/llvm/llvm-project/commit/70fdbf35de1c37a22a5321ed7d7d2c190d788549.diff

LOG: Adding DiBuilder interface for assumed length strings

Added: 
    

Modified: 
    llvm/docs/SourceLevelDebugging.rst
    llvm/include/llvm/IR/DIBuilder.h
    llvm/lib/IR/DIBuilder.cpp
    llvm/unittests/IR/DebugInfoTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/docs/SourceLevelDebugging.rst b/llvm/docs/SourceLevelDebugging.rst
index e4a529d0e2424..3cef7dda2c115 100644
--- a/llvm/docs/SourceLevelDebugging.rst
+++ b/llvm/docs/SourceLevelDebugging.rst
@@ -1086,7 +1086,10 @@ a Fortran front-end would generate the following descriptors:
 
   !DILocalVariable(name: "string", arg: 1, scope: !10, file: !3, line: 4, type: !15)
   !DIStringType(name: "character(*)!2", stringLength: !16, stringLengthExpression: !DIExpression(), size: 32)
+  
+A fortran deferred-length character can also contain the information of raw storage of the characters in addition to the length of the string. This information is encoded in the  stringLocationExpression field. Based on this information, DW_AT_data_location attribute is emitted in a DW_TAG_string_type debug info. 
 
+  !DIStringType(name: "character(*)!2", stringLengthExpression: !DIExpression(), stringLocationExpression: !DIExpression(DW_OP_push_object_address, DW_OP_deref), size: 32)
 and this will materialize in DWARF tags as:
 
 .. code-block:: text
@@ -1097,6 +1100,7 @@ and this will materialize in DWARF tags as:
    0x00000064:    DW_TAG_variable
                   DW_AT_location      (DW_OP_fbreg +16)
                   DW_AT_type  (0x00000083 "integer*8")
+                  DW_AT_data_location (DW_OP_push_object_address, DW_OP_deref)
                   ...
                   DW_AT_artificial    (true)
 

diff  --git a/llvm/include/llvm/IR/DIBuilder.h b/llvm/include/llvm/IR/DIBuilder.h
index d3aad3719900e..c635659fd625b 100644
--- a/llvm/include/llvm/IR/DIBuilder.h
+++ b/llvm/include/llvm/IR/DIBuilder.h
@@ -221,6 +221,23 @@ namespace llvm {
     /// \param SizeInBits  Size of the type.
     DIStringType *createStringType(StringRef Name, uint64_t SizeInBits);
 
+    /// Create debugging information entry for Fortran
+    /// assumed length string type.
+    /// \param Name            Type name.
+    /// \param StringLength    String length expressed as DIVariable *.
+    /// \param StrLocationExp  Optional memory location of the string.
+    DIStringType *createStringType(StringRef Name, DIVariable *StringLength,
+                                   DIExpression *StrLocationExp = nullptr);
+
+    /// Create debugging information entry for Fortran
+    /// assumed length string type.
+    /// \param Name             Type name.
+    /// \param StringLengthExp  String length expressed in DIExpression form.
+    /// \param StrLocationExp   Optional memory location of the string.
+    DIStringType *createStringType(StringRef Name,
+                                   DIExpression *StringLengthExp,
+                                   DIExpression *StrLocationExp = nullptr);
+
     /// Create debugging information entry for a qualified
     /// type, e.g. 'const int'.
     /// \param Tag         Tag identifing type, e.g. dwarf::TAG_volatile_type

diff  --git a/llvm/lib/IR/DIBuilder.cpp b/llvm/lib/IR/DIBuilder.cpp
index dc5768dd4f26a..16f7072d9d044 100644
--- a/llvm/lib/IR/DIBuilder.cpp
+++ b/llvm/lib/IR/DIBuilder.cpp
@@ -293,6 +293,22 @@ DIStringType *DIBuilder::createStringType(StringRef Name, uint64_t SizeInBits) {
                            SizeInBits, 0);
 }
 
+DIStringType *DIBuilder::createStringType(StringRef Name,
+                                          DIVariable *StringLength,
+                                          DIExpression *StrLocationExp) {
+  assert(!Name.empty() && "Unable to create type without name");
+  return DIStringType::get(VMContext, dwarf::DW_TAG_string_type, Name,
+                           StringLength, nullptr, StrLocationExp, 0, 0, 0);
+}
+
+DIStringType *DIBuilder::createStringType(StringRef Name,
+                                          DIExpression *StringLengthExp,
+                                          DIExpression *StrLocationExp) {
+  assert(!Name.empty() && "Unable to create type without name");
+  return DIStringType::get(VMContext, dwarf::DW_TAG_string_type, Name, nullptr,
+                           StringLengthExp, StrLocationExp, 0, 0, 0);
+}
+
 DIDerivedType *DIBuilder::createQualifiedType(unsigned Tag, DIType *FromTy) {
   return DIDerivedType::get(VMContext, Tag, "", nullptr, 0, nullptr, FromTy, 0,
                             0, 0, None, DINode::FlagZero);

diff  --git a/llvm/unittests/IR/DebugInfoTest.cpp b/llvm/unittests/IR/DebugInfoTest.cpp
index 8605fbbcbd401..524752168b091 100644
--- a/llvm/unittests/IR/DebugInfoTest.cpp
+++ b/llvm/unittests/IR/DebugInfoTest.cpp
@@ -247,6 +247,45 @@ TEST(DIBuilder, CreateSetType) {
   EXPECT_TRUE(isa_and_nonnull<DIDerivedType>(SetType));
 }
 
+TEST(DIBuilder, CreateStringType) {
+  LLVMContext Ctx;
+  std::unique_ptr<Module> M(new Module("MyModule", Ctx));
+  DIBuilder DIB(*M);
+  DIScope *Scope = DISubprogram::getDistinct(
+      Ctx, nullptr, "", "", nullptr, 0, nullptr, 0, nullptr, 0, 0,
+      DINode::FlagZero, DISubprogram::SPFlagZero, nullptr);
+  DIFile *F = DIB.createFile("main.c", "/");
+  StringRef StrName = "string";
+  DIVariable *StringLen = DIB.createAutoVariable(Scope, StrName, F, 0, nullptr,
+                                                 false, DINode::FlagZero, 0);
+  auto getDIExpression = [&DIB](int offset) {
+    SmallVector<uint64_t, 4> ops;
+    ops.push_back(llvm::dwarf::DW_OP_push_object_address);
+    DIExpression::appendOffset(ops, offset);
+    ops.push_back(llvm::dwarf::DW_OP_deref);
+
+    return DIB.createExpression(ops);
+  };
+  DIExpression *StringLocationExp = getDIExpression(1);
+  DIStringType *StringType =
+      DIB.createStringType(StrName, StringLen, StringLocationExp);
+
+  EXPECT_TRUE(isa_and_nonnull<DIStringType>(StringType));
+  EXPECT_EQ(StringType->getName(), StrName);
+  EXPECT_EQ(StringType->getStringLength(), StringLen);
+  EXPECT_EQ(StringType->getStringLocationExp(), StringLocationExp);
+
+  StringRef StrNameExp = "stringexp";
+  DIExpression *StringLengthExp = getDIExpression(2);
+  DIStringType *StringTypeExp =
+      DIB.createStringType(StrNameExp, StringLengthExp, StringLocationExp);
+
+  EXPECT_TRUE(isa_and_nonnull<DIStringType>(StringTypeExp));
+  EXPECT_EQ(StringTypeExp->getName(), StrNameExp);
+  EXPECT_EQ(StringTypeExp->getStringLocationExp(), StringLocationExp);
+  EXPECT_EQ(StringTypeExp->getStringLengthExp(), StringLengthExp);
+}
+
 TEST(DIBuilder, DIEnumerator) {
   LLVMContext Ctx;
   std::unique_ptr<Module> M(new Module("MyModule", Ctx));


        


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