[Dwarf][Transforms] Add dwarf support when func signature changed

llvm/include/llvm/BinaryFormat/Dwarf.def

@@ -268,6 +268,7 @@ HANDLE_DW_TAG(0x5111, ALTIUM_rom, 0, ALTIUM, DW_KIND_NONE)
 
 // LLVM
 HANDLE_DW_TAG(0x6000, LLVM_annotation, 0, LLVM, DW_KIND_NONE)
+HANDLE_DW_TAG(0x6001, LLVM_func_args_changed, 0, LLVM, DW_KIND_NONE)
 
 // Green Hills.
 HANDLE_DW_TAG(0x8004, GHS_namespace, 0, GHS, DW_KIND_NONE)
@@ -624,6 +625,7 @@ HANDLE_DW_AT(0x3e09, LLVM_ptrauth_authenticates_null_values, 0, LLVM)
 HANDLE_DW_AT(0x3e0a, LLVM_ptrauth_authentication_mode, 0, LLVM)
 HANDLE_DW_AT(0x3e0b, LLVM_num_extra_inhabitants, 0, LLVM)
 HANDLE_DW_AT(0x3e0c, LLVM_stmt_sequence, 0, LLVM)
+HANDLE_DW_AT(0x3e0d, LLVM_func_retval_removed, 0, LLVM)
 
 // Apple extensions.
 

llvm/include/llvm/IR/DebugInfoFlags.def

@@ -91,11 +91,13 @@ HANDLE_DISP_FLAG((1u << 8), MainSubprogram)
 // for defaulted functions
 HANDLE_DISP_FLAG((1u << 9), Deleted)
 HANDLE_DISP_FLAG((1u << 11), ObjCDirect)
+HANDLE_DISP_FLAG((1u << 12), ArgChanged)
+HANDLE_DISP_FLAG((1u << 13), RetvalRemoved)
 
 #ifdef DISP_FLAG_LARGEST_NEEDED
 // Intended to be used with ADT/BitmaskEnum.h.
 // NOTE: Always must be equal to largest flag, check this when adding new flags.
-HANDLE_DISP_FLAG((1 << 11), Largest)
+HANDLE_DISP_FLAG((1 << 13), Largest)
 #undef DISP_FLAG_LARGEST_NEEDED
 #endif
 

llvm/include/llvm/IR/DebugInfoMetadata.h

@@ -1907,6 +1907,11 @@ class DISubprogram : public DILocalScope {
 
   DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
 
+  void setArgChanged() { SPFlags |= SPFlagArgChanged; }
+  bool getArgChanged() const { return SPFlags & SPFlagArgChanged; }
+  void setRetvalRemoved() { SPFlags |= SPFlagRetvalRemoved; }
+  bool getRetvalRemoved() const { return SPFlags & SPFlagRetvalRemoved; }
+
   StringRef getName() const { return getStringOperand(2); }
   StringRef getLinkageName() const { return getStringOperand(3); }
   /// Only used by clients of CloneFunction, and only right after the cloning.

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -1123,6 +1123,8 @@ DIE &DwarfCompileUnit::constructSubprogramScopeDIE(const DISubprogram *Sub,
                                                    MCSymbol *LineTableSym) {
   DIE &ScopeDIE = updateSubprogramScopeDIE(Sub, LineTableSym);
 
+  DwarfUnit::addLLVMChangedArgs(ScopeDIE, Sub);
+
   if (Scope) {
     assert(!Scope->getInlinedAt());
     assert(!Scope->isAbstractScope());

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -654,6 +654,15 @@ DIE *DwarfUnit::getOrCreateTypeDIE(const MDNode *TyNode) {
       ->createTypeDIE(Context, *ContextDIE, Ty);
 }
 
+void DwarfUnit::addLLVMChangedArgs(DIE &ScopeDIE, const DISubprogram *SP) {
+  if (!SP->getArgChanged())
+    return;
+
+  auto *LocalDie =
+      DIE::get(DIEValueAllocator, dwarf::DW_TAG_LLVM_func_args_changed);
+  ScopeDIE.addChild(LocalDie);
+}
+
 void DwarfUnit::updateAcceleratorTables(const DIScope *Context,
                                         const DIType *Ty, const DIE &TyDIE) {
   if (Ty->getName().empty())
@@ -1328,6 +1337,9 @@ void DwarfUnit::applySubprogramAttributes(const DISubprogram *SP, DIE &SPDie,
   if (!SkipSPSourceLocation)
     addSourceLine(SPDie, SP);
 
+  if (SP->getRetvalRemoved())
+    addFlag(SPDie, dwarf::DW_AT_LLVM_func_retval_removed);
+
   // Skip the rest of the attributes under -gmlt to save space.
   if (SkipSPAttributes)
     return;

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h

@@ -324,6 +324,9 @@ class DwarfUnit : public DIEUnit {
   void updateAcceleratorTables(const DIScope *Context, const DIType *Ty,
                                const DIE &TyDIE);
 
+  /// Add DW_TAG_LLVM_func_args_changed.
+  void addLLVMChangedArgs(DIE &ScopeDIE, const DISubprogram *SP);
+
 protected:
   ~DwarfUnit();
 

llvm/lib/Transforms/IPO/ArgumentPromotion.cpp

@@ -51,6 +51,7 @@
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
@@ -132,6 +133,7 @@ doPromotion(Function *F, FunctionAnalysisManager &FAM,
 
   // First, determine the new argument list
   unsigned ArgNo = 0, NewArgNo = 0;
+  bool CurrFuncArgChanged = false;
   for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
        ++I, ++ArgNo) {
     if (!ArgsToPromote.count(&*I)) {
@@ -142,6 +144,7 @@ doPromotion(Function *F, FunctionAnalysisManager &FAM,
     } else if (I->use_empty()) {
       // Dead argument (which are always marked as promotable)
       ++NumArgumentsDead;
+      CurrFuncArgChanged = true;
       ORE.emit([&]() {
         return OptimizationRemark(DEBUG_TYPE, "ArgumentRemoved", F)
                << "eliminating argument " << ore::NV("ArgName", I->getName())
@@ -156,6 +159,7 @@ doPromotion(Function *F, FunctionAnalysisManager &FAM,
         ArgAttrVec.push_back(AttributeSet());
       }
       ++NumArgumentsPromoted;
+      CurrFuncArgChanged = true;
       ORE.emit([&]() {
         return OptimizationRemark(DEBUG_TYPE, "ArgumentPromoted", F)
                << "promoting argument " << ore::NV("ArgName", I->getName())
@@ -433,6 +437,10 @@ doPromotion(Function *F, FunctionAnalysisManager &FAM,
     PromoteMemToReg(Allocas, DT, &AC);
   }
 
+  DISubprogram *SP = NF->getSubprogram();
+  if (SP && CurrFuncArgChanged)
+    SP->setArgChanged();
+
   return NF;
 }
 

llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp

@@ -757,6 +757,8 @@ bool DeadArgumentEliminationPass::removeDeadStuffFromFunction(Function *F) {
   // a new set of parameter attributes to correspond. Skip the first parameter
   // attribute, since that belongs to the return value.
   unsigned ArgI = 0;
+  bool CurrFuncArgEliminated = false;
+  bool CurrFuncRetEliminated = false;
   for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
        ++I, ++ArgI) {
     RetOrArg Arg = createArg(F, ArgI);
@@ -767,6 +769,7 @@ bool DeadArgumentEliminationPass::removeDeadStuffFromFunction(Function *F) {
       HasLiveReturnedArg |= PAL.hasParamAttr(ArgI, Attribute::Returned);
     } else {
       ++NumArgumentsEliminated;
+      CurrFuncArgEliminated = true;
 
       ORE.emit([&]() {
         return OptimizationRemark(DEBUG_TYPE, "ArgumentRemoved", F)
@@ -818,6 +821,7 @@ bool DeadArgumentEliminationPass::removeDeadStuffFromFunction(Function *F) {
         NewRetIdxs[Ri] = RetTypes.size() - 1;
       } else {
         ++NumRetValsEliminated;
+        CurrFuncRetEliminated = true;
 
         ORE.emit([&]() {
           return OptimizationRemark(DEBUG_TYPE, "ReturnValueRemoved", F)
@@ -1099,6 +1103,12 @@ bool DeadArgumentEliminationPass::removeDeadStuffFromFunction(Function *F) {
   // to call this function or try to interpret the return value.
   if (NFTy != FTy && NF->getSubprogram()) {
     DISubprogram *SP = NF->getSubprogram();
+
+    if (CurrFuncArgEliminated)
+      SP->setArgChanged();
+    if (CurrFuncRetEliminated)
+      SP->setRetvalRemoved();
+
     auto Temp = SP->getType()->cloneWithCC(llvm::dwarf::DW_CC_nocall);
     SP->replaceType(MDNode::replaceWithPermanent(std::move(Temp)));
   }

llvm/test/DebugInfo/X86/arg-prom.ll

@@ -0,0 +1,95 @@
+; RUN: opt -S -passes=argpromotion < %s | FileCheck %s
+;
+; Source code:
+;   __attribute__((noinline)) static int is_absolute_path(const char *path)
+;   {
+;     return path[0] == '/';
+;   }
+;
+;   void quit(char *buf);
+;   const char *make_nonrelative_path(char *buf, const char *path)
+;   {
+;     if (is_absolute_path(path))
+;       quit(buf);
+;     return buf;
+;   }
+
+define dso_local ptr @make_nonrelative_path(ptr noundef %buf, ptr noundef %path) local_unnamed_addr #0 !dbg !10 {
+    #dbg_value(ptr %buf, !18, !DIExpression(), !20)
+    #dbg_value(ptr %path, !19, !DIExpression(), !20)
+  %x = call fastcc i32 @is_absolute_path(ptr noundef %path), !dbg !21
+  %y = icmp eq i32 %x, 0, !dbg !21
+  br i1 %y, label %to_ret, label %to_quit, !dbg !21
+
+to_quit:
+  call void @quit(ptr noundef %buf), !dbg !23
+  br label %to_ret, !dbg !23
+
+to_ret:
+  ret ptr %buf, !dbg !24
+}
+
+; Function Attrs: noinline nounwind uwtable
+define internal fastcc range(i32 0, 2) i32 @is_absolute_path(ptr noundef %path) unnamed_addr #1 !dbg !25 {
+    #dbg_value(ptr %path, !30, !DIExpression(), !31)
+  %x = load i8, ptr %path, align 1, !dbg !32, !tbaa !33
+  %y = icmp eq i8 %x, 47, !dbg !36
+  %z = zext i1 %y to i32, !dbg !36
+  ret i32 %z, !dbg !37
+}
+
+; CHECK: define internal fastcc range(i32 0, 2) i32 @is_absolute_path(i8 {{.*}})
+
+declare !dbg !38 void @quit(ptr noundef) local_unnamed_addr
+
+attributes #0 = { nounwind }
+attributes #1 = { noinline nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 21.0.0git ([email protected]:yonghong-song/llvm-project.git 25cfee009e78194d1f7ca70779d63ef1936cc7b9)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/tests/sig-change/prom", checksumkind: CSK_MD5, checksum: "bcc8cf18726713f5d2ab6d82e8ff459d")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+!9 = !{!"clang version 21.0.0git ([email protected]:yonghong-song/llvm-project.git 25cfee009e78194d1f7ca70779d63ef1936cc7b9)"}
+!10 = distinct !DISubprogram(name: "make_nonrelative_path", scope: !1, file: !1, line: 7, type: !11, scopeLine: 8, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !17)
+!11 = !DISubroutineType(types: !12)
+!12 = !{!13, !16, !13}
+!13 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !14, size: 64)
+!14 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !15)
+!15 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!16 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !15, size: 64)
+!17 = !{!18, !19}
+!18 = !DILocalVariable(name: "buf", arg: 1, scope: !10, file: !1, line: 7, type: !16)
+!19 = !DILocalVariable(name: "path", arg: 2, scope: !10, file: !1, line: 7, type: !13)
+!20 = !DILocation(line: 0, scope: !10)
+!21 = !DILocation(line: 9, column: 7, scope: !22)
+!22 = distinct !DILexicalBlock(scope: !10, file: !1, line: 9, column: 7)
+!23 = !DILocation(line: 10, column: 5, scope: !22)
+!24 = !DILocation(line: 11, column: 3, scope: !10)
+!25 = distinct !DISubprogram(name: "is_absolute_path", scope: !1, file: !1, line: 1, type: !26, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !29)
+
+; CHECK: distinct !DISubprogram(name: "is_absolute_path", scope: ![[#]], file: ![[#]], line: [[#]], type: ![[#]], scopeLine: [[#]], flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized | DISPFlagArgChanged, unit: ![[#]], retainedNodes: ![[#]])
+
+!26 = !DISubroutineType(types: !27)
+!27 = !{!28, !13}
+!28 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!29 = !{!30}
+!30 = !DILocalVariable(name: "path", arg: 1, scope: !25, file: !1, line: 1, type: !13)
+!31 = !DILocation(line: 0, scope: !25)
+!32 = !DILocation(line: 3, column: 10, scope: !25)
+!33 = !{!34, !34, i64 0}
+!34 = !{!"omnipotent char", !35, i64 0}
+!35 = !{!"Simple C/C++ TBAA"}
+!36 = !DILocation(line: 3, column: 18, scope: !25)
+!37 = !DILocation(line: 3, column: 3, scope: !25)
+!38 = !DISubprogram(name: "quit", scope: !1, file: !1, line: 6, type: !39, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
+!39 = !DISubroutineType(types: !40)
+!40 = !{null, !16}

llvm/test/DebugInfo/X86/arg-retval-elim.ll

@@ -0,0 +1,76 @@
+; RUN: opt -S -passes=deadargelim < %s | FileCheck %s
+;
+; Source code:
+;   int tar(int a);
+;   __attribute__((noinline)) static int foo(int a, int b)
+;   {
+;     return tar(a) + tar(a + 1);
+;   }
+;   int bar(int a)
+;   {
+;     foo(a, 1);
+;     return 0;
+;   }
+
+define dso_local noundef i32 @bar(i32 noundef %a) local_unnamed_addr #0 !dbg !10 {
+    #dbg_value(i32 %a, !15, !DIExpression(), !16)
+  %2 = tail call fastcc i32 @foo(i32 noundef %a, i32 noundef 1), !dbg !17
+  ret i32 0, !dbg !18
+}
+
+define internal fastcc i32 @foo(i32 noundef %a, i32 noundef %b) unnamed_addr #1 !dbg !19 {
+    #dbg_value(i32 %a, !23, !DIExpression(), !25)
+    #dbg_value(i32 %b, !24, !DIExpression(), !25)
+  %x = tail call i32 @tar(i32 noundef %a), !dbg !26
+  %t = add nsw i32 %a, 1, !dbg !27
+  %y = tail call i32 @tar(i32 noundef %t), !dbg !28
+  %z = add nsw i32 %y, %x, !dbg !29
+  ret i32 %z, !dbg !30
+}
+
+; CHECK: define internal fastcc void @foo(i32 noundef %a)
+
+declare !dbg !31 i32 @tar(i32 noundef) local_unnamed_addr
+
+attributes #0 = { nounwind }
+attributes #1 = { noinline nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 21.0.0git ([email protected]:yonghong-song/llvm-project.git 25cfee009e78194d1f7ca70779d63ef1936cc7b9)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/tests/sig-change/deadret", checksumkind: CSK_MD5, checksum: "728d225e6425c104712ae21cee1db99b")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+!9 = !{!"clang version 21.0.0git ([email protected]:yonghong-song/llvm-project.git 25cfee009e78194d1f7ca70779d63ef1936cc7b9)"}
+!10 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 6, type: !11, scopeLine: 7, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !14)
+!11 = !DISubroutineType(types: !12)
+!12 = !{!13, !13}
+!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!14 = !{!15}
+!15 = !DILocalVariable(name: "a", arg: 1, scope: !10, file: !1, line: 6, type: !13)
+!16 = !DILocation(line: 0, scope: !10)
+!17 = !DILocation(line: 8, column: 3, scope: !10)
+!18 = !DILocation(line: 9, column: 3, scope: !10)
+!19 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 2, type: !20, scopeLine: 3, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !22)
+
+; CHECK: distinct !DISubprogram(name: "foo", scope: ![[#]], file: ![[#]], line: [[#]], type: ![[#]], scopeLine: [[#]], flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized | DISPFlagArgChanged | DISPFlagRetvalRemoved, unit: !0, retainedNodes: ![[#]])
+
+!20 = !DISubroutineType(types: !21)
+!21 = !{!13, !13, !13}
+!22 = !{!23, !24}
+!23 = !DILocalVariable(name: "a", arg: 1, scope: !19, file: !1, line: 2, type: !13)
+!24 = !DILocalVariable(name: "b", arg: 2, scope: !19, file: !1, line: 2, type: !13)
+!25 = !DILocation(line: 0, scope: !19)
+!26 = !DILocation(line: 4, column: 10, scope: !19)
+!27 = !DILocation(line: 4, column: 25, scope: !19)
+!28 = !DILocation(line: 4, column: 19, scope: !19)
+!29 = !DILocation(line: 4, column: 17, scope: !19)
+!30 = !DILocation(line: 4, column: 3, scope: !19)
+!31 = !DISubprogram(name: "tar", scope: !1, file: !1, line: 1, type: !11, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)