On ELF, put PIC jump tables in a non executable section.

Fixes PR22558.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228939 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h b/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
index 0dc04100616c2f94c187c1e9d382ded00c56a818..348c634cfdf09f44cdf576a90fcb6ea35dec9940 100644 (file)
--- a/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
+++ b/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
@@ -60,6 +60,9 @@ public:
   getSectionForJumpTable(const Function &F, Mangler &Mang,
                          const TargetMachine &TM) const override;
 
   getSectionForJumpTable(const Function &F, Mangler &Mang,
                          const TargetMachine &TM) const override;
 

+  bool shouldPutJumpTableInFunctionSection(bool UsesLabelDifference,
+                                           const Function &F) const override;
+

   /// Return an MCExpr to use for a reference to the specified type info global
   /// variable from exception handling information.
   const MCExpr *
   /// Return an MCExpr to use for a reference to the specified type info global
   /// variable from exception handling information.
   const MCExpr *

diff --git a/include/llvm/Target/TargetLoweringObjectFile.h b/include/llvm/Target/TargetLoweringObjectFile.h
index ec29283bbe4117973f2150c04622f9b71cb525f2..2c30087a44fa938d022653e7c4bb2505170f4316 100644 (file)
--- a/include/llvm/Target/TargetLoweringObjectFile.h
+++ b/include/llvm/Target/TargetLoweringObjectFile.h
@@ -98,6 +98,9 @@ public:
   getSectionForJumpTable(const Function &F, Mangler &Mang,
                          const TargetMachine &TM) const;
 
   getSectionForJumpTable(const Function &F, Mangler &Mang,
                          const TargetMachine &TM) const;
 

+  virtual bool shouldPutJumpTableInFunctionSection(bool UsesLabelDifference,
+                                                   const Function &F) const;
+

   /// Targets should implement this method to assign a section to globals with
   /// an explicit section specfied. The implementation of this method can
   /// assume that GV->hasSection() is true.
   /// Targets should implement this method to assign a section to globals with
   /// an explicit section specfied. The implementation of this method can
   /// assume that GV->hasSection() is true.

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index aacc486aa147f99c8de92199d4e80a1443707ce9..5a01e0e9b6f20133f907fa40a805116f69294eac 100644 (file)
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1178,23 +1178,14 @@ void AsmPrinter::EmitJumpTableInfo() {
   // the appropriate section.
   const Function *F = MF->getFunction();
   const TargetLoweringObjectFile &TLOF = getObjFileLowering();
   // the appropriate section.
   const Function *F = MF->getFunction();
   const TargetLoweringObjectFile &TLOF = getObjFileLowering();

-  bool JTInDiffSection = false;
-  if (// In PIC mode, we need to emit the jump table to the same section as the
-      // function body itself, otherwise the label differences won't make sense.
-      // FIXME: Need a better predicate for this: what about custom entries?
-      MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 ||
-      // We should also do if the section name is NULL or function is declared
-      // in discardable section
-      // FIXME: this isn't the right predicate, should be based on the MCSection
-      // for the function.
-      F->isWeakForLinker()) {
-    OutStreamer.SwitchSection(TLOF.SectionForGlobal(F, *Mang, TM));
-  } else {
+  bool JTInDiffSection = !TLOF.shouldPutJumpTableInFunctionSection(
+      MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32,
+      *F);
+  if (JTInDiffSection) {

     // Otherwise, drop it in the readonly section.
     const MCSection *ReadOnlySection =
         TLOF.getSectionForJumpTable(*F, *Mang, TM);
     OutStreamer.SwitchSection(ReadOnlySection);
     // Otherwise, drop it in the readonly section.
     const MCSection *ReadOnlySection =
         TLOF.getSectionForJumpTable(*F, *Mang, TM);
     OutStreamer.SwitchSection(ReadOnlySection);

-    JTInDiffSection = true;

   }
 
   EmitAlignment(Log2_32(
   }
 
   EmitAlignment(Log2_32(

diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 0a49f5ff9fe365126aff5ee84b47b67b0c898831..4f46e37d39c711108787133a53d5f576e276a911 100644 (file)
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -356,6 +356,13 @@ const MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable(
   return getContext().getELFSection(Name, ELF::SHT_PROGBITS, Flags, 0, Group);
 }
 
   return getContext().getELFSection(Name, ELF::SHT_PROGBITS, Flags, 0, Group);
 }
 

+bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection(
+    bool UsesLabelDifference, const Function &F) const {
+  // We can always create relative relocations, so use another section
+  // that can be marked non-executable.
+  return false;
+}
+

 /// getSectionForConstant - Given a mergeable constant with the
 /// specified size and relocation information, return a section that it
 /// should be placed in.
 /// getSectionForConstant - Given a mergeable constant with the
 /// specified size and relocation information, return a section that it
 /// should be placed in.

diff --git a/lib/Target/TargetLoweringObjectFile.cpp b/lib/Target/TargetLoweringObjectFile.cpp
index c098035a5aa4b4edf0eec9f99f0ef1e9779bf650..faa6fbe6075dcf7f26c68af4259cb1e46ecdbb44 100644 (file)
--- a/lib/Target/TargetLoweringObjectFile.cpp
+++ b/lib/Target/TargetLoweringObjectFile.cpp
@@ -275,6 +275,24 @@ const MCSection *TargetLoweringObjectFile::getSectionForJumpTable(
   return getSectionForConstant(SectionKind::getReadOnly(), /*C=*/nullptr);
 }
 
   return getSectionForConstant(SectionKind::getReadOnly(), /*C=*/nullptr);
 }
 

+bool TargetLoweringObjectFile::shouldPutJumpTableInFunctionSection(
+    bool UsesLabelDifference, const Function &F) const {
+  // In PIC mode, we need to emit the jump table to the same section as the
+  // function body itself, otherwise the label differences won't make sense.
+  // FIXME: Need a better predicate for this: what about custom entries?
+  if (UsesLabelDifference)
+    return true;
+
+  // We should also do if the section name is NULL or function is declared
+  // in discardable section
+  // FIXME: this isn't the right predicate, should be based on the MCSection
+  // for the function.
+  if (F.isWeakForLinker())
+    return true;
+
+  return false;
+}
+

 /// getSectionForConstant - Given a mergable constant with the
 /// specified size and relocation information, return a section that it
 /// should be placed in.
 /// getSectionForConstant - Given a mergable constant with the
 /// specified size and relocation information, return a section that it
 /// should be placed in.

diff --git a/test/CodeGen/X86/global-sections.ll b/test/CodeGen/X86/global-sections.ll
index 4dc0f7d04c6f24f87edeedfa5aa0dc72662bce52..11b72c1e22208058933f6c75d8d32ac8bf751eff 100644 (file)
--- a/test/CodeGen/X86/global-sections.ll
+++ b/test/CodeGen/X86/global-sections.ll
@@ -3,6 +3,7 @@
 ; RUN: llc < %s -mtriple=i386-apple-darwin10 -relocation-model=static | FileCheck %s -check-prefix=DARWIN-STATIC
 ; RUN: llc < %s -mtriple=x86_64-apple-darwin10 | FileCheck %s -check-prefix=DARWIN64
 ; RUN: llc < %s -mtriple=i386-unknown-linux-gnu -data-sections -function-sections | FileCheck %s -check-prefix=LINUX-SECTIONS
 ; RUN: llc < %s -mtriple=i386-apple-darwin10 -relocation-model=static | FileCheck %s -check-prefix=DARWIN-STATIC
 ; RUN: llc < %s -mtriple=x86_64-apple-darwin10 | FileCheck %s -check-prefix=DARWIN64
 ; RUN: llc < %s -mtriple=i386-unknown-linux-gnu -data-sections -function-sections | FileCheck %s -check-prefix=LINUX-SECTIONS

+; RUN: llc < %s -mtriple=x86_64-pc-linux -data-sections -function-sections -relocation-model=pic | FileCheck %s -check-prefix=LINUX-SECTIONS-PIC

 ; RUN: llc < %s -mtriple=i686-pc-win32 -data-sections -function-sections | FileCheck %s -check-prefix=WIN32-SECTIONS
 
 define void @F1() {
 ; RUN: llc < %s -mtriple=i686-pc-win32 -data-sections -function-sections | FileCheck %s -check-prefix=WIN32-SECTIONS
 
 define void @F1() {


@@ -41,6 +42,11 @@ bb5:
 ; LINUX-SECTIONS-NEXT: .cfi_endproc
 ; LINUX-SECTIONS-NEXT: .section        .rodata.F2,"a",@progbits
 
 ; LINUX-SECTIONS-NEXT: .cfi_endproc
 ; LINUX-SECTIONS-NEXT: .section        .rodata.F2,"a",@progbits
 

+; LINUX-SECTIONS-PIC: .section        .text.F2,"ax",@progbits
+; LINUX-SECTIONS-PIC: .size   F2,
+; LINUX-SECTIONS-PIC-NEXT: .cfi_endproc
+; LINUX-SECTIONS-PIC-NEXT: .section        .rodata.F2,"a",@progbits
+

 ; int G1;
 @G1 = common global i32 0
 
 ; int G1;
 @G1 = common global i32 0