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https://github.com/c64scene-ar/llvm-6502.git
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Transform memmove -> memcpy when the source is obviously constant memory.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16932 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -35,10 +35,8 @@
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#define DEBUG_TYPE "instcombine"
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#define DEBUG_TYPE "instcombine"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Instructions.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Intrinsics.h"
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#include "llvm/Pass.h"
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#include "llvm/Pass.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Target/TargetData.h"
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@ -3094,23 +3092,42 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
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// CallInst simplification
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// CallInst simplification
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//
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//
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Instruction *InstCombiner::visitCallInst(CallInst &CI) {
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Instruction *InstCombiner::visitCallInst(CallInst &CI) {
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// Intrinsics cannot occur in an invoke, so handle them here instead of in
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// Intrinsics cannot occur in an invoke, so handle them here instead of in
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// visitCallSite.
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// visitCallSite.
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if (Function *F = CI.getCalledFunction())
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if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
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switch (F->getIntrinsicID()) {
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bool Changed = false;
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case Intrinsic::memmove:
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case Intrinsic::memcpy:
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// memmove/cpy/set of zero bytes is a noop.
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case Intrinsic::memset:
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if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
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// memmove/cpy/set of zero bytes is a noop.
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if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
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if (Constant *NumBytes = dyn_cast<Constant>(CI.getOperand(3))) {
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if (NumBytes->isNullValue())
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// FIXME: Increase alignment here.
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return EraseInstFromFunction(CI);
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}
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if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
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break;
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if (CI->getRawValue() == 1) {
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default:
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// Replace the instruction with just byte operations. We would
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break;
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// transform other cases to loads/stores, but we don't know if
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// alignment is sufficient.
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}
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}
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}
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// If we have a memmove and the source operation is a constant global,
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// then the source and dest pointers can't alias, so we can change this
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// into a call to memcpy.
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if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
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if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
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if (GVSrc->isConstant()) {
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Module *M = CI.getParent()->getParent()->getParent();
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Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
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CI.getCalledFunction()->getFunctionType());
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CI.setOperand(0, MemCpy);
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Changed = true;
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}
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if (Changed) return &CI;
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}
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return visitCallSite(&CI);
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return visitCallSite(&CI);
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}
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}
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