Speculatively micro-optimize memory-zeroing calls on Darwin 10.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@49048 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 275d4a0..f4ec6af 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -4560,6 +4560,11 @@
// address value and run time information about the CPU.
if ((Align & 3) != 0 ||
(I && I->getValue() > Subtarget->getMaxInlineSizeThreshold())) {
+
+ // Check to see if there is a specialized entry-point for memory zeroing.
+ const char *bzeroEntry = Subtarget->getBZeroEntry();
+ ConstantSDNode *V = dyn_cast<ConstantSDNode>(Op.getOperand(2));
+
MVT::ValueType IntPtr = getPointerTy();
const Type *IntPtrTy = getTargetData()->getIntPtrType();
TargetLowering::ArgListTy Args;
@@ -4567,15 +4572,20 @@
Entry.Node = Op.getOperand(1);
Entry.Ty = IntPtrTy;
Args.push_back(Entry);
- // Extend the unsigned i8 argument to be an int value for the call.
- Entry.Node = DAG.getNode(ISD::ZERO_EXTEND, MVT::i32, Op.getOperand(2));
- Entry.Ty = IntPtrTy;
- Args.push_back(Entry);
+
+ if (!bzeroEntry) {
+ // Extend the unsigned i8 argument to be an int value for the call.
+ Entry.Node = DAG.getNode(ISD::ZERO_EXTEND, MVT::i32, Op.getOperand(2));
+ Entry.Ty = IntPtrTy;
+ Args.push_back(Entry);
+ }
+
Entry.Node = Op.getOperand(3);
Args.push_back(Entry);
+ const char *Name = bzeroEntry ? bzeroEntry : "memset";
std::pair<SDOperand,SDOperand> CallResult =
LowerCallTo(Chain, Type::VoidTy, false, false, false, CallingConv::C,
- false, DAG.getExternalSymbol("memset", IntPtr), Args, DAG);
+ false, DAG.getExternalSymbol(Name, IntPtr), Args, DAG);
return CallResult.second;
}
diff --git a/lib/Target/X86/X86Subtarget.cpp b/lib/Target/X86/X86Subtarget.cpp
index 483b8a4..56bb7ac 100644
--- a/lib/Target/X86/X86Subtarget.cpp
+++ b/lib/Target/X86/X86Subtarget.cpp
@@ -53,6 +53,20 @@
return false;
}
+/// This function returns the name of a function which has an interface
+/// like the non-standard bzero function, if such a function exists on
+/// the current subtarget and it is considered prefereable over
+/// memset with zero passed as the second argument. Otherwise it
+/// returns null.
+const char *X86Subtarget::getBZeroEntry() const {
+
+ // Darwin 10 has a __bzero entry point for this purpose.
+ if (getDarwinVers() >= 10)
+ return "__bzero";
+
+ return 0;
+}
+
/// GetCpuIDAndInfo - Execute the specified cpuid and return the 4 values in the
/// specified arguments. If we can't run cpuid on the host, return true.
bool X86::GetCpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
diff --git a/lib/Target/X86/X86Subtarget.h b/lib/Target/X86/X86Subtarget.h
index 6488d47..c91088d 100644
--- a/lib/Target/X86/X86Subtarget.h
+++ b/lib/Target/X86/X86Subtarget.h
@@ -171,6 +171,12 @@
bool GVRequiresExtraLoad(const GlobalValue* GV, const TargetMachine& TM,
bool isDirectCall) const;
+ /// This function returns the name of a function which has an interface
+ /// like the non-standard bzero function, if such a function exists on
+ /// the current subtarget and it is considered prefereable over
+ /// memset with zero passed as the second argument. Otherwise it
+ /// returns null.
+ const char *getBZeroEntry() const;
};
namespace X86 {