Author: dpatel
Date: Thu Oct 11 12:21:57 2007
New Revision: 42864
URL: http://llvm.org/viewvc/llvm-project?rev=42864&view=rev
Log:
Lower memcpy if it makes sense.
Added:
llvm/trunk/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=42864&r1=42863&r2=42864&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Thu Oct 11
12:21:57 2007
@@ -7669,6 +7669,52 @@
MI->setAlignment(ConstantInt::get(Type::Int32Ty, Align));
Changed = true;
}
+
+ // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
load/store
+ ConstantInt *MemOpLength = dyn_cast<ConstantInt>(CI.getOperand(3));
+ if (isa<MemCpyInst>(MI))
+ if (MemOpLength) {
+ unsigned Size = MemOpLength->getZExtValue();
+ unsigned Align = cast<ConstantInt>(CI.getOperand(4))->getZExtValue();
+ const PointerType *PTy =
cast<PointerType>(CI.getOperand(1)->getType());
+ const Type *MTy = PTy->getElementType();
+ PointerType *NewPtrTy = NULL;
+ if (MTy == Type::Int8Ty) {
+ if (Size == 8)
+ NewPtrTy = PointerType::get(Type::Int64Ty);
+ else if (Size == 4)
+ NewPtrTy = PointerType::get(Type::Int32Ty);
+ else if (Size == 2)
+ NewPtrTy = PointerType::get(Type::Int16Ty);
+ else if (Size == 1)
+ NewPtrTy = PointerType::get(Type::Int8Ty);
+ } else if (MTy == Type::Int16Ty) {
+ if (Size == 4)
+ NewPtrTy = PointerType::get(Type::Int64Ty);
+ else if (Size == 2)
+ NewPtrTy = PointerType::get(Type::Int32Ty);
+ else if (Size == 1)
+ NewPtrTy = PointerType::get(Type::Int16Ty);
+ } else if (MTy == Type::Int32Ty) {
+ if (Size == 2)
+ NewPtrTy = PointerType::get(Type::Int64Ty);
+ else if (Size == 1)
+ NewPtrTy = PointerType::get(Type::Int32Ty);
+ } else if (MTy == Type::Int64Ty) {
+ if (Size == 1)
+ NewPtrTy = PointerType::get(Type::Int64Ty);
+ }
+ if (NewPtrTy)
+ {
+ Value *Src = InsertCastBefore(Instruction::BitCast,
CI.getOperand(2), NewPtrTy, CI);
+ Value *Dest = InsertCastBefore(Instruction::BitCast,
CI.getOperand(1), NewPtrTy, CI);
+ Value *L = new LoadInst(Src, "tmp", false, Align, &CI);
+ Value *NS = new StoreInst(L, Dest, false, Align, &CI);
+ CI.replaceAllUsesWith(NS);
+ Changed = true;
+ return EraseInstFromFunction(CI);
+ }
+ }
} else if (isa<MemSetInst>(MI)) {
unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest(), TD);
if (MI->getAlignment()->getZExtValue() < Alignment) {
Added: llvm/trunk/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll?rev=42864&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll Thu
Oct 11 12:21:57 2007
@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep call
[EMAIL PROTECTED] = internal constant [4 x i8] c"xyz\00" ; <[4 x
i8]*> [#uses=1]
+
+define void @foo(i8* %P) {
+entry:
+ %P_addr = alloca i8* ; <i8**> [#uses=2]
+ %"alloca point" = bitcast i32 0 to i32 ; <i32> [#uses=0]
+ store i8* %P, i8** %P_addr
+ %tmp = load i8** %P_addr, align 4 ; <i8*> [#uses=1]
+ %tmp1 = getelementptr [4 x i8]* @.str, i32 0, i32 0 ; <i8*>
[#uses=1]
+ call void @llvm.memcpy.i32( i8* %tmp, i8* %tmp1, i32 4, i32 1 )
+ br label %return
+
+return: ; preds = %entry
+ ret void
+}
+
+declare void @llvm.memcpy.i32(i8*, i8*, i32, i32)
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