move getDwarfExceptionSection from TAI to TLOF and rename it to

getLSDASection() to be more specific.  This makes it pretty obvious
that the ELF LSDA section is being specified wrong in PIC mode.  We're
probably getting a lot of startup-time relocations to a readonly page,
which is expensive and bad.

Someone who cares about ELF C++ should investigate this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77847 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Target/TargetAsmInfo.h b/include/llvm/Target/TargetAsmInfo.h
index 0eff044c45e39258204558534069f467bf76b212..5574ad5bc6b34062491a7bb5dde4b42bd4ce3a19 100644 (file)
--- a/include/llvm/Target/TargetAsmInfo.h
+++ b/include/llvm/Target/TargetAsmInfo.h
@@ -371,10 +371,6 @@ namespace llvm {
     ///
     const char *DwarfEHFrameSection; // Defaults to ".eh_frame".
     
-    /// DwarfExceptionSection - Section directive for Exception table.
-    ///
-    const char *DwarfExceptionSection; // Defaults to ".gcc_except_table".
-
     //===--- CBE Asm Translation Table -----------------------------------===//
 
     const char *const *AsmTransCBE; // Defaults to empty
@@ -637,9 +633,6 @@ namespace llvm {
     const char *getDwarfEHFrameSection() const {
       return DwarfEHFrameSection;
     }
-    const char *getDwarfExceptionSection() const {
-      return DwarfExceptionSection;
-    }
     const char *const *getAsmCBE() const {
       return AsmTransCBE;
     }

diff --git a/include/llvm/Target/TargetLoweringObjectFile.h b/include/llvm/Target/TargetLoweringObjectFile.h
index ec6b697585500894fbbf9cda9b53dcf59ae4a3b7..377b9eeae41e226446ef4143bfdd4ae905a8cda8 100644 (file)
--- a/include/llvm/Target/TargetLoweringObjectFile.h
+++ b/include/llvm/Target/TargetLoweringObjectFile.h
@@ -58,6 +58,10 @@ protected:
   /// list.
   const MCSection *StaticDtorSection;
   
+  /// LSDASection - If exception handling is supported by the target, this is
+  /// the section the Language Specific Data Area information is emitted to.
+  const MCSection *LSDASection;
+  
 public:
   // FIXME: NONPUB.
   const MCSection *getOrCreateSection(const char *Name,
@@ -77,10 +81,10 @@ public:
   
   const MCSection *getTextSection() const { return TextSection; }
   const MCSection *getDataSection() const { return DataSection; }
-
   const MCSection *getStaticCtorSection() const { return StaticCtorSection; }
   const MCSection *getStaticDtorSection() const { return StaticDtorSection; }
-
+  const MCSection *getLSDASection() const { return LSDASection; }
+  
   /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively
   /// decide not to emit the UsedDirective for some symbols in llvm.used.
   /// FIXME: REMOVE this (rdar://7071300)

diff --git a/lib/CodeGen/AsmPrinter/DwarfException.cpp b/lib/CodeGen/AsmPrinter/DwarfException.cpp
index 8eb97af0f942a568121598ddc9321c3040cb7bc5..b051f7138ef70849577d11548455e8a593a0544b 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfException.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfException.cpp
@@ -20,10 +20,11 @@
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetAsmInfo.h"
-#include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetFrameInfo.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/ADT/StringExtras.h"
 using namespace llvm;
 
@@ -539,10 +540,8 @@ void DwarfException::EmitExceptionTable() {
   unsigned SizeAlign = (4 - TotalSize) & 3;
 
   // Begin the exception table.
-  //MCSection *LSDASection = TAI->getLSDASection();
-  //Asm->SwitchToSection(LSDASection);
-  
-  Asm->SwitchToDataSection(TAI->getDwarfExceptionSection());
+  const MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
+  Asm->SwitchToSection(LSDASection);
   Asm->EmitAlignment(2, 0, 0, false);
   O << "GCC_except_table" << SubprogramCount << ":\n";
 

diff --git a/lib/Target/PowerPC/PPCTargetAsmInfo.cpp b/lib/Target/PowerPC/PPCTargetAsmInfo.cpp
index 3c8ab94da5a112e4726e1e937ef724c6168ec3ae..2e66cb80646849e326e9b93b0f47e528b8620959 100644 (file)
--- a/lib/Target/PowerPC/PPCTargetAsmInfo.cpp
+++ b/lib/Target/PowerPC/PPCTargetAsmInfo.cpp
@@ -28,7 +28,6 @@ PPCDarwinTargetAsmInfo::PPCDarwinTargetAsmInfo(const PPCTargetMachine &TM) :
   
   DwarfEHFrameSection =
    ".section __TEXT,__eh_frame,coalesced,no_toc+strip_static_syms+live_support";
-  DwarfExceptionSection = ".section __DATA,__gcc_except_tab";
   GlobalEHDirective = "\t.globl\t";
   SupportsWeakOmittedEHFrame = false;
 }
@@ -73,7 +72,6 @@ PPCLinuxTargetAsmInfo::PPCLinuxTargetAsmInfo(const PPCTargetMachine &TM) :
     SupportsExceptionHandling = true;
   AbsoluteEHSectionOffsets = false;
   DwarfEHFrameSection = "\t.section\t.eh_frame,\"aw\",@progbits";
-  DwarfExceptionSection = "\t.section\t.gcc_except_table,\"a\",@progbits";
 }
 
 

diff --git a/lib/Target/TargetAsmInfo.cpp b/lib/Target/TargetAsmInfo.cpp
index 80bb90e0651039f95ed227bec4fda453428393fe..e961f2ad74f3791b4abd338e4ccdd370fa86f729 100644 (file)
--- a/lib/Target/TargetAsmInfo.cpp
+++ b/lib/Target/TargetAsmInfo.cpp
@@ -108,7 +108,6 @@ TargetAsmInfo::TargetAsmInfo(const TargetMachine &tm) : TM(tm) {
   DwarfRangesSection = ".debug_ranges";
   DwarfMacroInfoSection = ".debug_macinfo";
   DwarfEHFrameSection = ".eh_frame";
-  DwarfExceptionSection = ".gcc_except_table";
   AsmTransCBE = 0;
 }
 

diff --git a/lib/Target/TargetLoweringObjectFile.cpp b/lib/Target/TargetLoweringObjectFile.cpp
index a86946da9f107513becec13f144fc595970931ef..d04e5c0cd609a5c1b7df984a69e4df412a4240e2 100644 (file)
--- a/lib/Target/TargetLoweringObjectFile.cpp
+++ b/lib/Target/TargetLoweringObjectFile.cpp
@@ -36,6 +36,7 @@ TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) {
   ReadOnlySection = 0;
   StaticCtorSection = 0;
   StaticDtorSection = 0;
+  LSDASection = 0;
 }
 
 TargetLoweringObjectFile::~TargetLoweringObjectFile() {
@@ -302,6 +303,14 @@ void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
     getOrCreateSection(".ctors", false, SectionKind::getDataRel());
   StaticDtorSection =
     getOrCreateSection(".dtors", false, SectionKind::getDataRel());
+  
+  
+  // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
+  // it contains relocatable pointers.  In PIC mode, this is probably a big
+  // runtime hit for C++ apps.  Either the contents of the LSDA need to be
+  // adjusted or this should be a data section.
+  LSDASection =
+    getOrCreateSection(".gcc_except_table", false, SectionKind::getReadOnly());
 }
 
 
@@ -537,6 +546,8 @@ void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
       getOrCreateSection(".mod_term_func", true, SectionKind::getDataRel());
   }
   
+  LSDASection = getOrCreateSection("__DATA,__gcc_except_tab", false,
+                                   SectionKind::getDataRel());
 }
 
 const MCSection *TargetLoweringObjectFileMachO::

diff --git a/lib/Target/X86/X86TargetAsmInfo.cpp b/lib/Target/X86/X86TargetAsmInfo.cpp
index c30f3378b7b100bec447a36073c7a8139916b852..4c9030845a0bbb8e1fa2635641b2ab5b76a9d84e 100644 (file)
--- a/lib/Target/X86/X86TargetAsmInfo.cpp
+++ b/lib/Target/X86/X86TargetAsmInfo.cpp
@@ -84,7 +84,6 @@ X86DarwinTargetAsmInfo::X86DarwinTargetAsmInfo(const X86TargetMachine &TM):
   AbsoluteEHSectionOffsets = false;
   DwarfEHFrameSection =
   ".section __TEXT,__eh_frame,coalesced,no_toc+strip_static_syms+live_support";
-  DwarfExceptionSection = ".section __DATA,__gcc_except_tab";
 }
 
 unsigned X86DarwinTargetAsmInfo::PreferredEHDataFormat() const {
@@ -133,7 +132,6 @@ X86ELFTargetAsmInfo::X86ELFTargetAsmInfo(const X86TargetMachine &TM) :
   SupportsExceptionHandling = true;
   AbsoluteEHSectionOffsets = false;
   DwarfEHFrameSection = "\t.section\t.eh_frame,\"aw\",@progbits";
-  DwarfExceptionSection = "\t.section\t.gcc_except_table,\"a\",@progbits";
 
   // On Linux we must declare when we can use a non-executable stack.
   if (TM.getSubtarget<X86Subtarget>().isLinux())