Use .cfi_sections to put the unwind info in .debug_frame when possible. With

this clang will use .debug_frame in, for example,
clang -g -c -m32 test.c
This matches gcc's behaviour. It looks like .debug_frame is a bit bigger
than .eh_frame, but has the big advantage of not being allocated.

llvm-svn: 131140

3 files changed, 21 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index d88f05b7ccd..7f39cef3f9e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -592,17 +592,17 @@ static bool EmitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
   return true;
 }
 
-bool AsmPrinter::needsCFIMoves() {
+AsmPrinter::CFIMoveType AsmPrinter::needsCFIMoves() {
   if (UnwindTablesMandatory)
-    return true;
+    return CFI_M_EH;
 
-  if (MMI->hasDebugInfo())
-    return true;
+  if (!MF->getFunction()->doesNotThrow())
+    return CFI_M_EH;
 
-  if (MF->getFunction()->doesNotThrow())
-    return false;
+  if (MMI->hasDebugInfo())
+    return CFI_M_Debug;
 
-  return true;
+  return CFI_M_None;
 }
 
 void AsmPrinter::emitPrologLabel(const MachineInstr &MI) {
@@ -611,7 +611,7 @@ void AsmPrinter::emitPrologLabel(const MachineInstr &MI) {
   if (MAI->getExceptionHandlingType() != ExceptionHandling::DwarfCFI)
     return;
 
-  if (!needsCFIMoves())
+  if (needsCFIMoves() == CFI_M_None)
     return;
 
   MachineModuleInfo &MMI = MF->getMMI();
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
index dbd52c4981b..e7a7593be3b 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -49,6 +49,9 @@ DwarfCFIException::~DwarfCFIException() {}
 /// EndModule - Emit all exception information that should come after the
 /// content.
 void DwarfCFIException::EndModule() {
+  if (moveTypeModule == AsmPrinter::CFI_M_Debug)
+    Asm->OutStreamer.EmitCFISections(false, true);
+
   if (!Asm->MAI->isExceptionHandlingDwarf())
     return;
 
@@ -87,7 +90,13 @@ void DwarfCFIException::BeginFunction(const MachineFunction *MF) {
   bool hasLandingPads = !MMI->getLandingPads().empty();
 
   // See if we need frame move info.
-  shouldEmitMoves = Asm->needsCFIMoves();
+  AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
+  if (MoveType == AsmPrinter::CFI_M_EH ||
+      (MoveType == AsmPrinter::CFI_M_Debug &&
+       moveTypeModule == AsmPrinter::CFI_M_None))
+    moveTypeModule = MoveType;
+
+  shouldEmitMoves = MoveType != AsmPrinter::CFI_M_None;
 
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
   unsigned PerEncoding = TLOF.getPersonalityEncoding();
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfException.h b/llvm/lib/CodeGen/AsmPrinter/DwarfException.h
index de5fc90cd3b..68079bb655a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfException.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfException.h
@@ -15,6 +15,7 @@
 #define LLVM_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
 
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/CodeGen/AsmPrinter.h"
 #include <vector>
 
 namespace llvm {
@@ -152,6 +153,8 @@ class DwarfCFIException : public DwarfException {
   /// should be emitted.
   bool shouldEmitMoves;
 
+  AsmPrinter::CFIMoveType moveTypeModule;
+
 public:
   //===--------------------------------------------------------------------===//
   // Main entry points.