[llvm-commits] [llvm] r50634 - in /llvm/trunk: include/llvm/Target/TargetAsmInfo.h lib/CodeGen/AsmPrinter.cpp lib/Target/TargetAsmInfo.cpp lib/Target/X86/X86Subtarget.cpp lib/Target/X86/X86Subtarget.h lib/Target/X86/X86TargetAsmInfo.cpp test/CodeGen/X86/xor_not.ll

Dan Gohman gohman at apple.com
Sun May 4 17:28:39 PDT 2008


Author: djg
Date: Sun May  4 19:28:39 2008
New Revision: 50634

URL: http://llvm.org/viewvc/llvm-project?rev=50634&view=rev
Log:
Add AsmPrinter support for emitting a directive to declare that
the code being generated does not require an executable stack.

Also, add target-specific code to make use of this on Linux
on x86. 

Modified:
    llvm/trunk/include/llvm/Target/TargetAsmInfo.h
    llvm/trunk/lib/CodeGen/AsmPrinter.cpp
    llvm/trunk/lib/Target/TargetAsmInfo.cpp
    llvm/trunk/lib/Target/X86/X86Subtarget.cpp
    llvm/trunk/lib/Target/X86/X86Subtarget.h
    llvm/trunk/lib/Target/X86/X86TargetAsmInfo.cpp
    llvm/trunk/test/CodeGen/X86/xor_not.ll

Modified: llvm/trunk/include/llvm/Target/TargetAsmInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetAsmInfo.h?rev=50634&r1=50633&r2=50634&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Target/TargetAsmInfo.h (original)
+++ llvm/trunk/include/llvm/Target/TargetAsmInfo.h Sun May  4 19:28:39 2008
@@ -61,10 +61,16 @@
     /// Null if this target doesn't support a BSS section.
     ///
     const char *TLSBSSSection;// Default to ".section .tbss,"awT", at nobits".
+
     /// ZeroFillDirective - Directive for emitting a global to the ZeroFill
     /// section on this target.  Null if this target doesn't support zerofill.
     const char *ZeroFillDirective;        // Default is null.
     
+    /// NonexecutableStackDirective - Directive for declaring to the
+    /// linker and beyond that the emitted code does not require stack
+    /// memory to be executable.
+    const char *NonexecutableStackDirective; // Default is null.
+
     /// NeedsSet - True if target asm treats expressions in data directives
     /// as linktime-relocatable.  For assembly-time computation, we need to
     /// use a .set.  Thus:
@@ -440,6 +446,9 @@
     const char *getZeroFillDirective() const {
       return ZeroFillDirective;
     }
+    const char *getNonexecutableStackDirective() const {
+      return NonexecutableStackDirective;
+    }
     bool needsSet() const {
       return NeedsSet;
     }

Modified: llvm/trunk/lib/CodeGen/AsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter.cpp?rev=50634&r1=50633&r2=50634&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter.cpp Sun May  4 19:28:39 2008
@@ -192,6 +192,13 @@
                                          E = CMM->begin(); I != E; )
     (*--I)->finishAssembly(O, *this, *TAI);
 
+  // If we don't have any trampolines, then we don't require stack memory
+  // to be executable. Some targets have a directive to declare this.
+  Function* InitTrampolineIntrinsic = M.getFunction("llvm.init.trampoline");
+  if (!InitTrampolineIntrinsic || InitTrampolineIntrinsic->use_empty())
+    if (TAI->getNonexecutableStackDirective())
+      O << TAI->getNonexecutableStackDirective() << "\n";
+
   delete Mang; Mang = 0;
   return false;
 }

Modified: llvm/trunk/lib/Target/TargetAsmInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/TargetAsmInfo.cpp?rev=50634&r1=50633&r2=50634&view=diff

==============================================================================
--- llvm/trunk/lib/Target/TargetAsmInfo.cpp (original)
+++ llvm/trunk/lib/Target/TargetAsmInfo.cpp Sun May  4 19:28:39 2008
@@ -26,6 +26,7 @@
   TLSDataSection("\t.section .tdata,\"awT\", at progbits"),
   TLSBSSSection("\t.section .tbss,\"awT\", at nobits"),
   ZeroFillDirective(0),
+  NonexecutableStackDirective(0),
   NeedsSet(false),
   MaxInstLength(4),
   PCSymbol("$"),

Modified: llvm/trunk/lib/Target/X86/X86Subtarget.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86Subtarget.cpp?rev=50634&r1=50633&r2=50634&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/X86Subtarget.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86Subtarget.cpp Sun May  4 19:28:39 2008
@@ -278,6 +278,8 @@
         DarwinVers = atoi(&TT[Pos+7]);
       else
         DarwinVers = 8;  // Minimum supported darwin is Tiger.
+    } else if (TT.find("linux") != std::string::npos) {
+      TargetType = isELFLinux;
     } else if (TT.find("cygwin") != std::string::npos) {
       TargetType = isCygwin;
     } else if (TT.find("mingw") != std::string::npos) {
@@ -302,6 +304,9 @@
     
 #elif defined(_WIN32) || defined(_WIN64)
     TargetType = isWindows;
+#elif defined(__linux__)
+    // Linux doesn't imply ELF, but we don't currently support anything else.
+    TargetType = isELFLinux;
 #endif
   }
 

Modified: llvm/trunk/lib/Target/X86/X86Subtarget.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86Subtarget.h?rev=50634&r1=50633&r2=50634&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/X86Subtarget.h (original)
+++ llvm/trunk/lib/Target/X86/X86Subtarget.h Sun May  4 19:28:39 2008
@@ -84,7 +84,7 @@
 
 public:
   enum {
-    isELF, isCygwin, isDarwin, isWindows, isMingw
+    isELF, isELFLinux, isCygwin, isDarwin, isWindows, isMingw
   } TargetType;
 
   /// This constructor initializes the data members to match that
@@ -132,7 +132,12 @@
   bool isFlavorIntel() const { return AsmFlavor == Intel; }
 
   bool isTargetDarwin() const { return TargetType == isDarwin; }
-  bool isTargetELF() const { return TargetType == isELF; }
+  bool isTargetELF() const {
+    return TargetType == isELF || TargetType == isELFLinux;
+  }
+  bool isTargetLinux() const {
+    return TargetType == isELFLinux;
+  }
   bool isTargetWindows() const { return TargetType == isWindows; }
   bool isTargetMingw() const { return TargetType == isMingw; }
   bool isTargetCygMing() const { return (TargetType == isMingw ||

Modified: llvm/trunk/lib/Target/X86/X86TargetAsmInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86TargetAsmInfo.cpp?rev=50634&r1=50633&r2=50634&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/X86TargetAsmInfo.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86TargetAsmInfo.cpp Sun May  4 19:28:39 2008
@@ -128,6 +128,7 @@
     break;
 
   case X86Subtarget::isELF:
+  case X86Subtarget::isELFLinux:
     ReadOnlySection = "\t.section\t.rodata";
     FourByteConstantSection = "\t.section\t.rodata.cst4,\"aM\", at progbits,4";
     EightByteConstantSection = "\t.section\t.rodata.cst8,\"aM\", at progbits,8";
@@ -229,6 +230,10 @@
     SectionEndDirectiveSuffix = "\tends\n";
   }
 
+  // On Linux we must declare when we can use a non-executable stack.
+  if (Subtarget->isTargetLinux())
+    NonexecutableStackDirective = "\t.section\t.note.GNU-stack,\"\", at progbits";
+
   AssemblerDialect = Subtarget->getAsmFlavor();
 }
 

Modified: llvm/trunk/test/CodeGen/X86/xor_not.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/xor_not.ll?rev=50634&r1=50633&r2=50634&view=diff

==============================================================================
--- llvm/trunk/test/CodeGen/X86/xor_not.ll (original)
+++ llvm/trunk/test/CodeGen/X86/xor_not.ll Sun May  4 19:28:39 2008
@@ -1,5 +1,5 @@
-; RUN: llvm-as < %s | llc -march=x86 | grep {not} | count 3
-; RUN: llvm-as < %s | llc -march=x86-64 | grep {not}  | count 4
+; RUN: llvm-as < %s | llc -march=x86 | grep {not\[lwb\]} | count 3
+; RUN: llvm-as < %s | llc -march=x86-64 | grep {not\[lwb\]}  | count 4
 define i32 @test(i32 %a, i32 %b) nounwind  {
 entry:
         %tmp1not = xor i32 %b, -2





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