Add hook in MCSection to decide when to use "optimized nops", for each

section kind. Previously, optimized nops were only used for MachO.
Also added tests for ELF and COFF.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115523 91177308-0d34-0410-b5e6-96231b3b80d8

13 files changed, 113 insertions, 9 deletions

diff --git a/include/llvm/MC/MCSection.h b/include/llvm/MC/MCSection.h
index 5c997357c9..3e5b5f13f3 100644
--- a/include/llvm/MC/MCSection.h
+++ b/include/llvm/MC/MCSection.h
@@ -61,6 +61,10 @@ namespace llvm {
       return false;
     }
 
+    // UseCodeAlign - Return true if a .align directive should use
+    // "optimized nops" to fill instead of 0s.
+    virtual bool UseCodeAlign() const = 0;
+
     static bool classof(const MCSection *) { return true; }
   };
 
diff --git a/include/llvm/MC/MCSectionCOFF.h b/include/llvm/MC/MCSectionCOFF.h
index f828e1060f..62d07cf436 100644
--- a/include/llvm/MC/MCSectionCOFF.h
+++ b/include/llvm/MC/MCSectionCOFF.h
@@ -55,6 +55,7 @@ namespace llvm {
     
     virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
                                       raw_ostream &OS) const;
+    virtual bool UseCodeAlign() const;
 
     static bool classof(const MCSection *S) {
       return S->getVariant() == SV_COFF;
diff --git a/include/llvm/MC/MCSectionELF.h b/include/llvm/MC/MCSectionELF.h
index f97ab16711..a92d0f2c95 100644
--- a/include/llvm/MC/MCSectionELF.h
+++ b/include/llvm/MC/MCSectionELF.h
@@ -178,7 +178,8 @@ public:
   
   void PrintSwitchToSection(const MCAsmInfo &MAI,
                             raw_ostream &OS) const;
-  
+  virtual bool UseCodeAlign() const;
+
   /// isBaseAddressKnownZero - We know that non-allocatable sections (like
   /// debug info) have a base of zero.
   virtual bool isBaseAddressKnownZero() const {
diff --git a/include/llvm/MC/MCSectionMachO.h b/include/llvm/MC/MCSectionMachO.h
index 2d9d1333db..19d003a3b5 100644
--- a/include/llvm/MC/MCSectionMachO.h
+++ b/include/llvm/MC/MCSectionMachO.h
@@ -165,6 +165,7 @@ public:
 
   virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
                                     raw_ostream &OS) const;
+  virtual bool UseCodeAlign() const;
 
   static bool classof(const MCSection *S) {
     return S->getVariant() == SV_MachO;
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index fbac34a15e..688827d2c7 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -1654,12 +1654,7 @@ bool AsmParser::ParseDirectiveAlign(bool IsPow2, unsigned ValueSize) {
 
   // Check whether we should use optimal code alignment for this .align
   // directive.
-  //
-  // FIXME: This should be using a target hook.
-  bool UseCodeAlign = false;
-  if (const MCSectionMachO *S = dyn_cast<MCSectionMachO>(
-        getStreamer().getCurrentSection()))
-    UseCodeAlign = S->hasAttribute(MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS);
+  bool UseCodeAlign = getStreamer().getCurrentSection()->UseCodeAlign();
   if ((!HasFillExpr || Lexer.getMAI().getTextAlignFillValue() == FillExpr) &&
       ValueSize == 1 && UseCodeAlign) {
     getStreamer().EmitCodeAlignment(Alignment, MaxBytesToFill);
diff --git a/lib/MC/MCSectionCOFF.cpp b/lib/MC/MCSectionCOFF.cpp
index eb531600f7..0909df4222 100644
--- a/lib/MC/MCSectionCOFF.cpp
+++ b/lib/MC/MCSectionCOFF.cpp
@@ -74,3 +74,7 @@ void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI,
     }
   }
 }
+
+bool MCSectionCOFF::UseCodeAlign() const {
+  return getKind().isText();
+}
diff --git a/lib/MC/MCSectionELF.cpp b/lib/MC/MCSectionELF.cpp
index ef935d0c64..133cad1b32 100644
--- a/lib/MC/MCSectionELF.cpp
+++ b/lib/MC/MCSectionELF.cpp
@@ -112,6 +112,10 @@ void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI,
   OS << '\n';
 }
 
+bool MCSectionELF::UseCodeAlign() const {
+  return getFlags() & MCSectionELF::SHF_EXECINSTR;
+}
+
 // HasCommonSymbols - True if this section holds common symbols, this is
 // indicated on the ELF object file by a symbol with SHN_COMMON section 
 // header index.
diff --git a/lib/MC/MCSectionMachO.cpp b/lib/MC/MCSectionMachO.cpp
index ded3b20eaf..12b3efe663 100644
--- a/lib/MC/MCSectionMachO.cpp
+++ b/lib/MC/MCSectionMachO.cpp
@@ -148,6 +148,10 @@ void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo &MAI,
   OS << '\n';
 }
 
+bool MCSectionMachO::UseCodeAlign() const {
+  return hasAttribute(MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS);
+}
+
 /// StripSpaces - This removes leading and trailing spaces from the StringRef.
 static void StripSpaces(StringRef &Str) {
   while (!Str.empty() && isspace(Str[0]))
@@ -283,4 +287,3 @@ std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
   
   return "";
 }
-
diff --git a/lib/Target/PIC16/PIC16Section.cpp b/lib/Target/PIC16/PIC16Section.cpp
index 2505b111f1..7664fbbb7d 100644
--- a/lib/Target/PIC16/PIC16Section.cpp
+++ b/lib/Target/PIC16/PIC16Section.cpp
@@ -102,3 +102,7 @@ void PIC16Section::PrintSwitchToSection(const MCAsmInfo &MAI,
 
   OS << '\n';
 }
+
+bool PIC16Section::UseCodeAlign() const {
+  return isCODE_Type();
+}
diff --git a/lib/Target/PIC16/PIC16Section.h b/lib/Target/PIC16/PIC16Section.h
index 5b33b51a38..98e590229b 100644
--- a/lib/Target/PIC16/PIC16Section.h
+++ b/lib/Target/PIC16/PIC16Section.h
@@ -88,6 +88,8 @@ namespace llvm {
     virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
                                       raw_ostream &OS) const;
 
+    virtual bool UseCodeAlign() const;
+
     static bool classof(const MCSection *S) {
       return S->getVariant() == SV_PIC16;
     }
diff --git a/test/MC/COFF/align-nops.s b/test/MC/COFF/align-nops.s
new file mode 100644
index 0000000000..f190fdb9a2
--- /dev/null
+++ b/test/MC/COFF/align-nops.s
@@ -0,0 +1,45 @@
+// RUN: llvm-mc -filetype=obj -triple i686-pc-win32 %s -o %t
+// RUN: coff-dump.py %abs_tmp | FileCheck %s
+        
+// Test that we get optimal nops in text
+    .text
+f0:
+    .long 0
+    .align  8, 0x90
+    .long 0
+    .align  8
+
+// But not in another section
+    .data
+    .long 0
+    .align  8, 0x90
+    .long 0
+    .align  8
+
+//CHECK:         Name                     = .text
+//CHECK-NEXT:    VirtualSize
+//CHECK-NEXT:    VirtualAddress
+//CHECK-NEXT:    SizeOfRawData            = 16
+//CHECK-NEXT:    PointerToRawData
+//CHECK-NEXT:    PointerToRelocations
+//CHECK-NEXT:    PointerToLineNumbers
+//CHECK-NEXT:    NumberOfRelocations
+//CHECK-NEXT:    NumberOfLineNumbers
+//CHECK-NEXT:    Charateristics           = 0x400001
+//CHECK-NEXT:        IMAGE_SCN_ALIGN_8BYTES
+//CHECK-NEXT:      SectionData              = 
+//CHECK-NEXT:        00 00 00 00 0F 1F 40 00 - 00 00 00 00 0F 1F 40 00
+
+//CHECK:         Name                     = .data
+//CHECK-NEXT:      VirtualSize
+//CHECK-NEXT:      VirtualAddress
+//CHECK-NEXT:      SizeOfRawData            = 16
+//CHECK-NEXT:      PointerToRawData
+//CHECK-NEXT:      PointerToRelocations
+//CHECK-NEXT:      PointerToLineNumbers
+//CHECK-NEXT:      NumberOfRelocations
+//CHECK-NEXT:      NumberOfLineNumbers
+//CHECK-NEXT:      Charateristics           = 0x400001
+//CHECK-NEXT:        IMAGE_SCN_ALIGN_8BYTES
+//CHECK-NEXT:      SectionData              = 
+//CHECK-NEXT:        00 00 00 00 90 90 90 90 - 00 00 00 00 00 00 00 00
diff --git a/test/MC/COFF/dg.exp b/test/MC/COFF/dg.exp
index 7b7bd4e738..d46d700975 100644
--- a/test/MC/COFF/dg.exp
+++ b/test/MC/COFF/dg.exp
@@ -1,5 +1,5 @@
 load_lib llvm.exp
 
 if { [llvm_supports_target X86] } {
-  RunLLVMTests [lsort [glob -nocomplain $srcdir/$subdir/*.{ll}]]
+  RunLLVMTests [lsort [glob -nocomplain $srcdir/$subdir/*.{ll,s}]]
 }
diff --git a/test/MC/ELF/align-nops.s b/test/MC/ELF/align-nops.s
new file mode 100644
index 0000000000..b6793ecb67
--- /dev/null
+++ b/test/MC/ELF/align-nops.s
@@ -0,0 +1,40 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump --dump-section-data | FileCheck %s
+
+// Test that we get optimal nops in text
+    .text
+f0:
+    .long 0
+    .align  8, 0x90
+    .long 0
+    .align  8
+
+// But not in another section
+    .data
+    .long 0
+    .align  8, 0x90
+    .long 0
+    .align  8
+
+// CHECK: (('sh_name', 1) # '.text'
+// CHECK-NEXT:  ('sh_type', 1)
+// CHECK-NEXT:  ('sh_flags', 6)
+// CHECK-NEXT:  ('sh_addr',
+// CHECK-NEXT:  ('sh_offset',
+// CHECK-NEXT:  ('sh_size', 16)
+// CHECK-NEXT:  ('sh_link', 0)
+// CHECK-NEXT:  ('sh_info', 0)
+// CHECK-NEXT:  ('sh_addralign', 8)
+// CHECK-NEXT:  ('sh_entsize', 0)
+// CHECK-NEXT:  ('_section_data', '00000000 0f1f4000 00000000 0f1f4000')
+
+// CHECK: (('sh_name', 7) # '.data'
+// CHECK-NEXT:  ('sh_type', 1)
+// CHECK-NEXT:  ('sh_flags', 3)
+// CHECK-NEXT:  ('sh_addr',
+// CHECK-NEXT:  ('sh_offset',
+// CHECK-NEXT:  ('sh_size', 16)
+// CHECK-NEXT:  ('sh_link', 0)
+// CHECK-NEXT:  ('sh_info', 0)
+// CHECK-NEXT:  ('sh_addralign', 8)
+// CHECK-NEXT:  ('sh_entsize', 0)
+// CHECK-NEXT:  ('_section_data', '00000000 90909090 00000000 00000000')