Added small section asm emition logic for mips.

Fixed small bug.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53908 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/Mips/MipsISelLowering.cpp

@@ -241,10 +241,11 @@ AddLiveIn(MachineFunction &MF, unsigned PReg, TargetRegisterClass *RC)
 bool MipsTargetLowering::IsGlobalInSmallSection(GlobalValue *GV)
 {
   const TargetData *TD = getTargetData();
-  const Value *V = dyn_cast<Value>(GV);
-  const GlobalVariable *GVA = dyn_cast<GlobalVariable>(V);
+  const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV);
+
+  if (!GVA)
+    return false;
   
-  //const PointerType *PTy = GV->getType();
   const Type *Ty = GV->getType()->getElementType();
   unsigned Size = TD->getABITypeSize(Ty);
 

lib/Target/Mips/MipsTargetAsmInfo.cpp

@@ -19,6 +19,8 @@ using namespace llvm;
 MipsTargetAsmInfo::MipsTargetAsmInfo(const MipsTargetMachine &TM):
   ELFTargetAsmInfo(TM) {
 
+  MipsTM = &TM;
+
   AlignmentIsInBytes          = false;
   COMMDirectiveTakesAlignment = true;
   Data16bitsDirective         = "\t.half\t";
@@ -37,5 +39,66 @@ MipsTargetAsmInfo::MipsTargetAsmInfo(const MipsTargetMachine &TM):
     JumpTableDirective = "\t.word\t";
   else
     JumpTableDirective = "\t.gpword\t";
-
+  
+  SmallDataSection = getNamedSection("\t.sdata", SectionFlags::Writeable);
+  SmallBSSSection  = getNamedSection("\t.sbss",
+                         SectionFlags::Writeable | SectionFlags::BSS);
+}
+
+static bool isSuitableForBSS(const GlobalVariable *GV) {
+  if (!GV->hasInitializer())
+    return true;
+
+  // Leave constant zeros in readonly constant sections, so they can be shared
+  Constant *C = GV->getInitializer();
+  return (C->isNullValue() && !GV->isConstant() && !NoZerosInBSS);
+}
+
+SectionKind::Kind
+MipsTargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
+  const TargetData *TD = ETM->getTargetData();
+  const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV);
+
+  if (!GVA)
+    return ELFTargetAsmInfo::SectionKindForGlobal(GV);
+  
+  // if this is a internal constant string, there is a special
+  // section for it, but not in small data/bss.
+  if (GVA->hasInitializer() && GV->hasInternalLinkage()) {
+    Constant *C = GVA->getInitializer();
+    const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
+    if (CVA && CVA->isCString()) 
+      return ELFTargetAsmInfo::SectionKindForGlobal(GV);
+  }
+
+  const Type *Ty = GV->getType()->getElementType();
+  unsigned Size = TD->getABITypeSize(Ty);
+  unsigned Threshold = 
+    MipsTM->getSubtarget<MipsSubtarget>().getSSectionThreshold();
+
+  if (Size > 0 && Size <= Threshold) {
+    if (isSuitableForBSS(GVA))
+      return SectionKind::SmallBSS;
+    else
+      return SectionKind::SmallData;
+  }
+
+  return ELFTargetAsmInfo::SectionKindForGlobal(GV);
+}
+
+const Section*
+MipsTargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
+  SectionKind::Kind K = SectionKindForGlobal(GV);
+  const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV);
+
+  if (GVA && (!GVA->isWeakForLinker()))
+    switch (K) {
+      case SectionKind::SmallData:
+        return getSmallDataSection();
+      case SectionKind::SmallBSS:
+        return getSmallBSSSection();
+      default: break;
+    }
+
+  return ELFTargetAsmInfo::SelectSectionForGlobal(GV);
 }

lib/Target/Mips/MipsTargetAsmInfo.h

@@ -16,6 +16,9 @@
 
 #include "llvm/Target/TargetAsmInfo.h"
 #include "llvm/Target/ELFTargetAsmInfo.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/Target/TargetOptions.h"
 
 namespace llvm {
 
@@ -24,6 +27,17 @@ namespace llvm {
 
   struct MipsTargetAsmInfo : public ELFTargetAsmInfo {
     explicit MipsTargetAsmInfo(const MipsTargetMachine &TM);
+
+    /// SectionKindForGlobal - This hook allows the target to select proper
+    /// section kind used for global emission.
+    virtual SectionKind::Kind
+    SectionKindForGlobal(const GlobalValue *GV) const;
+
+    virtual const Section* SelectSectionForGlobal(const GlobalValue *GV) const;
+
+    private:
+      const MipsTargetMachine *MipsTM; 
+
   };
 
 } // namespace llvm