PR 31534: When emitting both DWARF unwind tables and debug information,

do not use .cfi_sections. This requires checking if any non-declaration
function in the module needs an unwind table.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291172 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/AsmPrinter.h

@@ -140,6 +140,9 @@ class AsmPrinter : public MachineFunctionPass {
   /// If the target supports dwarf debug info, this pointer is non-null.
   DwarfDebug *DD;
 
+  /// If the current module uses dwarf CFI annotations strictly for debugging.
+  bool isCFIMoveForDebugging;
+
 protected:
   explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
 
@@ -262,6 +265,10 @@ class AsmPrinter : public MachineFunctionPass {
   enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
   CFIMoveType needsCFIMoves();
 
+  /// Returns false if needsCFIMoves() == CFI_M_EH for any function
+  /// in the module.
+  bool needsOnlyDebugCFIMoves() const { return isCFIMoveForDebugging; }
+
   bool needsSEHMoves();
 
   /// Print to the current output stream assembly representations of the

lib/CodeGen/AsmPrinter/ARMException.cpp

@@ -53,7 +53,8 @@ void ARMException::beginFunction(const MachineFunction *MF) {
 
   if (MoveType == AsmPrinter::CFI_M_Debug) {
     if (!hasEmittedCFISections) {
-      Asm->OutStreamer->EmitCFISections(false, true);
+      if (Asm->needsOnlyDebugCFIMoves())
+        Asm->OutStreamer->EmitCFISections(false, true);
       hasEmittedCFISections = true;
     }
 

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -108,7 +108,7 @@ static unsigned getGVAlignmentLog2(const GlobalValue *GV, const DataLayout &DL,
 AsmPrinter::AsmPrinter(TargetMachine &tm, std::unique_ptr<MCStreamer> Streamer)
     : MachineFunctionPass(ID), TM(tm), MAI(tm.getMCAsmInfo()),
       OutContext(Streamer->getContext()), OutStreamer(std::move(Streamer)),
-      LastMI(nullptr), LastFn(0), Counter(~0U) {
+      isCFIMoveForDebugging(false), LastMI(nullptr), LastFn(0), Counter(~0U) {
   DD = nullptr;
   MMI = nullptr;
   LI = nullptr;
@@ -264,6 +264,28 @@ bool AsmPrinter::doInitialization(Module &M) {
     }
   }
 
+  switch (MAI->getExceptionHandlingType()) {
+  case ExceptionHandling::SjLj:
+  case ExceptionHandling::DwarfCFI:
+  case ExceptionHandling::ARM:
+    isCFIMoveForDebugging = true;
+    if (MAI->getExceptionHandlingType() != ExceptionHandling::DwarfCFI)
+      break;
+    for (auto &F: M.getFunctionList()) {
+      // If the module contains any function with unwind data,
+      // .eh_frame has to be emitted.
+      // Ignore functions that won't get emitted.
+      if (!F.isDeclarationForLinker() && F.needsUnwindTableEntry()) {
+        isCFIMoveForDebugging = false;
+        break;
+      }
+    }
+    break;
+  default:
+    isCFIMoveForDebugging = false;
+    break;
+  }
+
   EHStreamer *ES = nullptr;
   switch (MAI->getExceptionHandlingType()) {
   case ExceptionHandling::None:

lib/CodeGen/AsmPrinter/DwarfCFIException.cpp

@@ -137,7 +137,7 @@ void DwarfCFIException::beginFragment(const MachineBasicBlock *MBB,
     return;
 
   if (!hasEmittedCFISections) {
-    if (Asm->needsCFIMoves() == AsmPrinter::CFI_M_Debug)
+    if (Asm->needsOnlyDebugCFIMoves())
       Asm->OutStreamer->EmitCFISections(false, true);
     hasEmittedCFISections = true;
   }

test/CodeGen/Generic/cfi-sections.ll

@@ -0,0 +1,39 @@
+; When using Itanium ABI, do not emit .debug_frame.
+; RUNT: llc -mtriple=i386--linux -o - < %s | FileCheck %s -check-prefix=WITHOUT
+; RUNT: llc -mtriple=armv7-netbsd-eabi -o - < %s | FileCheck %s -check-prefix=WITHOUT
+
+; When using EHABI, do emit .debug_frame.
+; RUN: llc -mtriple=arm-linux -mcpu=cortex-a7 -mattr=v7 -o - < %s | FileCheck %s -check-prefix=WITH
+
+; REQUIRES: x86-registered-target
+; REQUIRES: arm-registered-target
+
+; WITH:        .cfi_sections .debug_frame
+; WITHOUT-NOT: .cfi_sections
+
+define i32 @foo() #0 !dbg !7 {
+  %1 = call i32 @bar()
+  %2 = call i32 @bar()
+  %3 = add nsw i32 %1, %2
+  ret i32 %3
+}
+
+declare i32 @bar() #1
+
+attributes #0 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="arm7tdmi" "target-features"="+soft-float,+strict-align,-crypto,-neon" "unsafe-fp-math"="false" "use-soft-float"="true" }
+attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="arm7tdmi" "target-features"="+soft-float,+strict-align,-crypto,-neon" "unsafe-fp-math"="false" "use-soft-float"="true" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5, !6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "cfi-sections.cc", directory: ".")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{i32 1, !"min_enum_size", i32 4}
+!7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 2, type: !8, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10}
+!10 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)