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https://github.com/c64scene-ar/llvm-6502.git
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9e77f7e08b
first element of a structure type. Before this would not be handled because getStructOffset would either stop immediately (because StopEarly was true and Offset = 0), or blast past the level we wanted. Now ConvertableToGEP steps down through the type one level at a time, checking the Offset and Scale conditions at each step git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1931 91177308-0d34-0410-b5e6-96231b3b80d8
274 lines
11 KiB
C++
274 lines
11 KiB
C++
//===-- TransformInternals.cpp - Implement shared functions for transforms --=//
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//
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// This file defines shared functions used by the different components of the
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// Transforms library.
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//
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//===----------------------------------------------------------------------===//
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#include "TransformInternals.h"
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#include "llvm/Method.h"
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#include "llvm/Type.h"
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#include "llvm/ConstantVals.h"
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#include "llvm/Analysis/Expressions.h"
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#include "llvm/iOther.h"
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#include <algorithm>
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// TargetData Hack: Eventually we will have annotations given to us by the
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// backend so that we know stuff about type size and alignments. For now
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// though, just use this, because it happens to match the model that GCC uses.
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//
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const TargetData TD("LevelRaise: Should be GCC though!");
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// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI)
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// with a value, then remove and delete the original instruction.
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//
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void ReplaceInstWithValue(BasicBlock::InstListType &BIL,
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BasicBlock::iterator &BI, Value *V) {
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Instruction *I = *BI;
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// Replaces all of the uses of the instruction with uses of the value
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I->replaceAllUsesWith(V);
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// Remove the unneccesary instruction now...
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BIL.remove(BI);
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// Make sure to propogate a name if there is one already...
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if (I->hasName() && !V->hasName())
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V->setName(I->getName(), BIL.getParent()->getSymbolTable());
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// Remove the dead instruction now...
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delete I;
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}
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// ReplaceInstWithInst - Replace the instruction specified by BI with the
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// instruction specified by I. The original instruction is deleted and BI is
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// updated to point to the new instruction.
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//
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void ReplaceInstWithInst(BasicBlock::InstListType &BIL,
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BasicBlock::iterator &BI, Instruction *I) {
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assert(I->getParent() == 0 &&
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"ReplaceInstWithInst: Instruction already inserted into basic block!");
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// Insert the new instruction into the basic block...
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BI = BIL.insert(BI, I)+1; // Increment BI to point to instruction to delete
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// Replace all uses of the old instruction, and delete it.
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ReplaceInstWithValue(BIL, BI, I);
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// Move BI back to point to the newly inserted instruction
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--BI;
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}
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void ReplaceInstWithInst(Instruction *From, Instruction *To) {
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BasicBlock *BB = From->getParent();
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BasicBlock::InstListType &BIL = BB->getInstList();
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BasicBlock::iterator BI = find(BIL.begin(), BIL.end(), From);
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assert(BI != BIL.end() && "Inst not in it's parents BB!");
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ReplaceInstWithInst(BIL, BI, To);
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}
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// InsertInstBeforeInst - Insert 'NewInst' into the basic block that 'Existing'
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// is already in, and put it right before 'Existing'. This instruction should
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// only be used when there is no iterator to Existing already around. The
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// returned iterator points to the new instruction.
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//
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BasicBlock::iterator InsertInstBeforeInst(Instruction *NewInst,
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Instruction *Existing) {
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BasicBlock *BB = Existing->getParent();
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BasicBlock::InstListType &BIL = BB->getInstList();
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BasicBlock::iterator BI = find(BIL.begin(), BIL.end(), Existing);
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assert(BI != BIL.end() && "Inst not in it's parents BB!");
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return BIL.insert(BI, NewInst);
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}
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static const Type *getStructOffsetStep(const StructType *STy, unsigned &Offset,
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std::vector<Value*> &Indices) {
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assert(Offset < TD.getTypeSize(STy) && "Offset not in composite!");
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const StructLayout *SL = TD.getStructLayout(STy);
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// This loop terminates always on a 0 <= i < MemberOffsets.size()
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unsigned i;
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for (i = 0; i < SL->MemberOffsets.size()-1; ++i)
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if (Offset >= SL->MemberOffsets[i] && Offset < SL->MemberOffsets[i+1])
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break;
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assert(Offset >= SL->MemberOffsets[i] &&
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(i == SL->MemberOffsets.size()-1 || Offset < SL->MemberOffsets[i+1]));
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// Make sure to save the current index...
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Indices.push_back(ConstantUInt::get(Type::UByteTy, i));
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Offset = SL->MemberOffsets[i];
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return STy->getContainedType(i);
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}
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// getStructOffsetType - Return a vector of offsets that are to be used to index
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// into the specified struct type to get as close as possible to index as we
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// can. Note that it is possible that we cannot get exactly to Offset, in which
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// case we update offset to be the offset we actually obtained. The resultant
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// leaf type is returned.
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//
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// If StopEarly is set to true (the default), the first object with the
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// specified type is returned, even if it is a struct type itself. In this
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// case, this routine will not drill down to the leaf type. Set StopEarly to
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// false if you want a leaf
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//
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const Type *getStructOffsetType(const Type *Ty, unsigned &Offset,
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std::vector<Value*> &Indices,
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bool StopEarly = true) {
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if (Offset == 0 && StopEarly && !Indices.empty())
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return Ty; // Return the leaf type
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unsigned ThisOffset;
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const Type *NextType;
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if (const StructType *STy = dyn_cast<StructType>(Ty)) {
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ThisOffset = Offset;
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NextType = getStructOffsetStep(STy, ThisOffset, Indices);
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} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
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assert(Offset < TD.getTypeSize(ATy) && "Offset not in composite!");
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NextType = ATy->getElementType();
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unsigned ChildSize = TD.getTypeSize(NextType);
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Indices.push_back(ConstantUInt::get(Type::UIntTy, Offset/ChildSize));
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ThisOffset = (Offset/ChildSize)*ChildSize;
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} else {
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Offset = 0; // Return the offset that we were able to acheive
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return Ty; // Return the leaf type
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}
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unsigned SubOffs = Offset - ThisOffset;
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const Type *LeafTy = getStructOffsetType(NextType, SubOffs,
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Indices, StopEarly);
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Offset = ThisOffset + SubOffs;
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return LeafTy;
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}
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// ConvertableToGEP - This function returns true if the specified value V is
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// a valid index into a pointer of type Ty. If it is valid, Idx is filled in
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// with the values that would be appropriate to make this a getelementptr
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// instruction. The type returned is the root type that the GEP would point to
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//
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const Type *ConvertableToGEP(const Type *Ty, Value *OffsetVal,
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std::vector<Value*> &Indices,
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BasicBlock::iterator *BI = 0) {
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const CompositeType *CompTy = dyn_cast<CompositeType>(Ty);
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if (CompTy == 0) return 0;
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// See if the cast is of an integer expression that is either a constant,
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// or a value scaled by some amount with a possible offset.
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//
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analysis::ExprType Expr = analysis::ClassifyExpression(OffsetVal);
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// Get the offset and scale now...
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// A scale of zero with Expr.Var != 0 means a scale of 1.
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//
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// TODO: Handle negative offsets for C code like this:
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// for (unsigned i = 12; i < 14; ++i) x[j*i-12] = ...
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unsigned Offset = 0;
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int Scale = 0;
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// Get the offset value if it exists...
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if (Expr.Offset) {
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int Val = getConstantValue(Expr.Offset);
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if (Val < 0) return false; // Don't mess with negative offsets
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Offset = (unsigned)Val;
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}
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// Get the scale value if it exists...
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if (Expr.Scale) Scale = getConstantValue(Expr.Scale);
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if (Expr.Var && Scale == 0) Scale = 1; // Scale != 0 if Expr.Var != 0
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// Loop over the Scale and Offset values, filling in the Indices vector for
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// our final getelementptr instruction.
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//
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const Type *NextTy = CompTy;
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do {
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if (!isa<CompositeType>(NextTy))
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return 0; // Type must not be ready for processing...
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CompTy = cast<CompositeType>(NextTy);
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if (const StructType *StructTy = dyn_cast<StructType>(CompTy)) {
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// Step into the appropriate element of the structure...
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unsigned ActualOffset = Offset;
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NextTy = getStructOffsetStep(StructTy, ActualOffset, Indices);
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Offset -= ActualOffset;
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} else {
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const Type *ElTy = cast<SequentialType>(CompTy)->getElementType();
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if (!ElTy->isSized())
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return 0; // Type is unreasonable... escape!
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unsigned ElSize = TD.getTypeSize(ElTy);
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int ElSizeS = (int)ElSize;
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// See if the user is indexing into a different cell of this array...
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if (Scale && (Scale >= ElSizeS || -Scale >= ElSizeS)) {
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// A scale n*ElSize might occur if we are not stepping through
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// array by one. In this case, we will have to insert math to munge
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// the index.
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//
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int ScaleAmt = Scale/ElSizeS;
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if (Scale-ScaleAmt*ElSizeS)
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return 0; // Didn't scale by a multiple of element size, bail out
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Scale = 0; // Scale is consumed
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unsigned Index = Offset/ElSize; // is zero unless Offset > ElSize
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Offset -= Index*ElSize; // Consume part of the offset
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if (BI) { // Generate code?
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BasicBlock *BB = (**BI)->getParent();
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if (Expr.Var->getType() != Type::UIntTy) {
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CastInst *IdxCast = new CastInst(Expr.Var, Type::UIntTy);
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if (Expr.Var->hasName())
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IdxCast->setName(Expr.Var->getName()+"-idxcast");
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*BI = BB->getInstList().insert(*BI, IdxCast)+1;
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Expr.Var = IdxCast;
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}
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if (ScaleAmt && ScaleAmt != 1) {
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// If we have to scale up our index, do so now
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Value *ScaleAmtVal = ConstantUInt::get(Type::UIntTy,
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(unsigned)ScaleAmt);
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Instruction *Scaler = BinaryOperator::create(Instruction::Mul,
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Expr.Var, ScaleAmtVal);
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if (Expr.Var->hasName())
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Scaler->setName(Expr.Var->getName()+"-scale");
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*BI = BB->getInstList().insert(*BI, Scaler)+1;
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Expr.Var = Scaler;
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}
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if (Index) { // Add an offset to the index
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Value *IndexAmt = ConstantUInt::get(Type::UIntTy, Index);
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Instruction *Offseter = BinaryOperator::create(Instruction::Add,
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Expr.Var, IndexAmt);
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if (Expr.Var->hasName())
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Offseter->setName(Expr.Var->getName()+"-offset");
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*BI = BB->getInstList().insert(*BI, Offseter)+1;
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Expr.Var = Offseter;
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}
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}
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Indices.push_back(Expr.Var);
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Expr.Var = 0;
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} else if (Offset >= ElSize) {
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// Calculate the index that we are entering into the array cell with
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unsigned Index = Offset/ElSize;
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Indices.push_back(ConstantUInt::get(Type::UIntTy, Index));
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Offset -= Index*ElSize; // Consume part of the offset
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} else if (isa<ArrayType>(CompTy) || Indices.empty()) {
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// Must be indexing a small amount into the first cell of the array
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// Just index into element zero of the array here.
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//
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Indices.push_back(ConstantUInt::get(Type::UIntTy, 0));
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} else {
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return 0; // Hrm. wierd, can't handle this case. Bail
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}
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NextTy = ElTy;
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}
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} while (Offset || Scale); // Go until we're done!
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return NextTy;
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}
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