Added initial support for small sections on Mips.
Added gp_rel relocations to support addressing small section contents.
Added command line to specify small section threshold in bytes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53869 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index efc5d9b..668e57d 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -20,6 +20,7 @@
#include "MipsSubtarget.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
+#include "llvm/GlobalVariable.h"
#include "llvm/Intrinsics.h"
#include "llvm/CallingConv.h"
#include "llvm/CodeGen/CallingConvLower.h"
@@ -43,6 +44,7 @@
case MipsISD::JmpLink : return "MipsISD::JmpLink";
case MipsISD::Hi : return "MipsISD::Hi";
case MipsISD::Lo : return "MipsISD::Lo";
+ case MipsISD::GPRel : return "MipsISD::GPRel";
case MipsISD::Ret : return "MipsISD::Ret";
case MipsISD::SelectCC : return "MipsISD::SelectCC";
case MipsISD::FPBrcond : return "MipsISD::FPBrcond";
@@ -89,8 +91,6 @@
setOperationAction(ISD::SELECT_CC, MVT::f32, Custom);
// Operations not directly supported by Mips.
- setConvertAction(MVT::f64, MVT::f32, Expand);
-
setOperationAction(ISD::BR_JT, MVT::Other, Expand);
setOperationAction(ISD::BR_CC, MVT::Other, Expand);
setOperationAction(ISD::SELECT_CC, MVT::Other, Expand);
@@ -234,34 +234,71 @@
return VReg;
}
+// Discover if this global address can be placed into small data/bss section.
+// This should happen for globals with size less than small section size
+// threshold in no abicall environments. Data in this section must be addressed
+// using gp_rel operator.
+bool MipsTargetLowering::IsGlobalInSmallSection(GlobalValue *GV)
+{
+ const TargetData *TD = getTargetData();
+ const Value *V = dyn_cast<Value>(GV);
+ const GlobalVariable *GVA = dyn_cast<GlobalVariable>(V);
+
+ //const PointerType *PTy = GV->getType();
+ const Type *Ty = GV->getType()->getElementType();
+ unsigned Size = TD->getABITypeSize(Ty);
+
+ // 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 false;
+ }
+
+ if (Size > 0 && (Size <= Subtarget->getSSectionThreshold()))
+ return true;
+
+ return false;
+}
+
//===----------------------------------------------------------------------===//
// Misc Lower Operation implementation
//===----------------------------------------------------------------------===//
SDOperand MipsTargetLowering::
LowerGlobalAddress(SDOperand Op, SelectionDAG &DAG)
{
- SDOperand ResNode;
GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
SDOperand GA = DAG.getTargetGlobalAddress(GV, MVT::i32);
- bool isPIC = (getTargetMachine().getRelocationModel() == Reloc::PIC_);
- SDOperand HiPart;
- if (!isPIC) {
+ if (!Subtarget->hasABICall()) {
+ if (isa<Function>(GV)) return GA;
const MVT *VTs = DAG.getNodeValueTypes(MVT::i32);
SDOperand Ops[] = { GA };
- HiPart = DAG.getNode(MipsISD::Hi, VTs, 1, Ops, 1);
- } else // Emit Load from Global Pointer
- HiPart = DAG.getLoad(MVT::i32, DAG.getEntryNode(), GA, NULL, 0);
- // On functions and global targets not internal linked only
- // a load from got/GP is necessary for PIC to work.
- if ((isPIC) && ((!GV->hasInternalLinkage()) || (isa<Function>(GV))))
- return HiPart;
+ if (IsGlobalInSmallSection(GV)) { // %gp_rel relocation
+ SDOperand GPRelNode = DAG.getNode(MipsISD::GPRel, VTs, 1, Ops, 1);
+ SDOperand GOT = DAG.getNode(ISD::GLOBAL_OFFSET_TABLE, MVT::i32);
+ return DAG.getNode(ISD::ADD, MVT::i32, GOT, GPRelNode);
+ }
+ // %hi/%lo relocation
+ SDOperand HiPart = DAG.getNode(MipsISD::Hi, VTs, 1, Ops, 1);
+ SDOperand Lo = DAG.getNode(MipsISD::Lo, MVT::i32, GA);
+ return DAG.getNode(ISD::ADD, MVT::i32, HiPart, Lo);
- SDOperand Lo = DAG.getNode(MipsISD::Lo, MVT::i32, GA);
- ResNode = DAG.getNode(ISD::ADD, MVT::i32, HiPart, Lo);
+ } else { // Abicall relocations, TODO: make this cleaner.
+ SDOperand ResNode = DAG.getLoad(MVT::i32, DAG.getEntryNode(), GA, NULL, 0);
+ // On functions and global targets not internal linked only
+ // a load from got/GP is necessary for PIC to work.
+ if (!GV->hasInternalLinkage() || isa<Function>(GV))
+ return ResNode;
+ SDOperand Lo = DAG.getNode(MipsISD::Lo, MVT::i32, GA);
+ return DAG.getNode(ISD::ADD, MVT::i32, ResNode, Lo);
+ }
- return ResNode;
+ assert(0 && "Dont know how to handle GlobalAddress");
+ return SDOperand(0,0);
}
SDOperand MipsTargetLowering::
@@ -596,9 +633,8 @@
unsigned StackReg = MF.getTarget().getRegisterInfo()->getFrameRegister(MF);
- // GP holds the GOT address on PIC calls.
- if (getTargetMachine().getRelocationModel() == Reloc::PIC_)
- AddLiveIn(MF, Mips::GP, Mips::CPURegsRegisterClass);
+ // GP must be live into PIC and non-PIC call target.
+ AddLiveIn(MF, Mips::GP, Mips::CPURegsRegisterClass);
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;