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call libc memcpy/memset if array size is bigger then threshold.

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Coping 100MB array (after a warmup) shows that glibc 2.6.1 implementation on
x86-64 (core 2) is 30% faster (from 0.270917s to 0.188079s)

llvm-svn: 41479
This commit is contained in:
Rafael Espindola 2007-08-27 10:18:20 +00:00
parent 3dffac0c59
commit 3d52fe3ef3
2 changed files with 20 additions and 18 deletions
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8
lib/Target/X86/X86ISelLowering.cpp
View File

@ -3753,10 +3753,10 @@ SDOperand X86TargetLowering::LowerMEMSET(SDOperand Op, SelectionDAG &DAG) {
if (Align == 0) Align = 1;
ConstantSDNode *I = dyn_cast<ConstantSDNode>(Op.getOperand(3));
// If not DWORD aligned, call memset if size is less than the threshold.
// If not DWORD aligned or size is more than the threshold, call memset.
// It knows how to align to the right boundary first.
if ((Align & 3) != 0 ||
(I && I->getValue() < Subtarget->getMinRepStrSizeThreshold())) {
(I && I->getValue() > Subtarget->getMinRepStrSizeThreshold())) {
MVT::ValueType IntPtr = getPointerTy();
const Type *IntPtrTy = getTargetData()->getIntPtrType();
TargetLowering::ArgListTy Args;
@ -3909,10 +3909,10 @@ SDOperand X86TargetLowering::LowerMEMCPY(SDOperand Op, SelectionDAG &DAG) {
if (Align == 0) Align = 1;
ConstantSDNode *I = dyn_cast<ConstantSDNode>(Op.getOperand(3));
// If not DWORD aligned, call memcpy if size is less than the threshold.
// If not DWORD aligned or size is more than the threshold, call memcpy.
// It knows how to align to the right boundary first.
if ((Align & 3) != 0 ||
(I && I->getValue() < Subtarget->getMinRepStrSizeThreshold())) {
(I && I->getValue() > Subtarget->getMinRepStrSizeThreshold())) {
MVT::ValueType IntPtr = getPointerTy();
TargetLowering::ArgListTy Args;
TargetLowering::ArgListEntry Entry;

30
test/CodeGen/X86/2004-02-12-Memcpy.llx
View File

@ -1,24 +1,26 @@
; RUN: llvm-upgrade < %s | llvm-as | llc -march=x86 | grep movs
declare void %llvm.memcpy.i32(sbyte* %A, sbyte* %B, uint %amt, uint %align)
; RUN: llvm-as < %s | llc -march=x86 | grep movs | count 1
; RUN: llvm-as < %s | llc -march=x86 | grep memcpy | count 2
%A = global [1000 x int] zeroinitializer
%B = global [1000 x int] zeroinitializer
@A = global [32 x i32] zeroinitializer
@B = global [32 x i32] zeroinitializer
declare void @llvm.memcpy.i32(i8*, i8*, i32, i32)
void %main() {
define void @main() {
; dword copy
call void %llvm.memcpy.i32(sbyte* cast (int* getelementptr ([1000 x int]* %A, long 0, long 0) to sbyte*),
sbyte* cast (int* getelementptr ([1000 x int]* %B, long 0, long 0) to sbyte*),
uint 4000, uint 4)
call void @llvm.memcpy.i32(i8* bitcast ([32 x i32]* @A to i8*),
i8* bitcast ([32 x i32]* @B to i8*),
i32 128, i32 4 )
; word copy
call void %llvm.memcpy.i32(sbyte* cast (int* getelementptr ([1000 x int]* %A, long 0, long 0) to sbyte*),
sbyte* cast (int* getelementptr ([1000 x int]* %B, long 0, long 0) to sbyte*),
uint 4000, uint 2)
call void @llvm.memcpy.i32( i8* bitcast ([32 x i32]* @A to i8*),
i8* bitcast ([32 x i32]* @B to i8*),
i32 128, i32 2 )
; byte copy
call void %llvm.memcpy.i32(sbyte* cast (int* getelementptr ([1000 x int]* %A, long 0, long 0) to sbyte*),
sbyte* cast (int* getelementptr ([1000 x int]* %B, long 0, long 0) to sbyte*),
uint 4000, uint 1)
call void @llvm.memcpy.i32( i8* bitcast ([32 x i32]* @A to i8*),
i8* bitcast ([32 x i32]* @B to i8*),
i32 128, i32 1 )
ret void
}