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llvm-project/polly/lib/CodeGen/IslExprBuilder.cpp

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//===------ IslExprBuilder.cpp ----- Code generate isl AST expressions ----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//
#include "polly/CodeGen/IslExprBuilder.h"
#include "polly/ScopInfo.h"
#include "polly/Support/GICHelper.h"
#include "polly/Support/ScopHelper.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;
using namespace polly;
Type *IslExprBuilder::getWidestType(Type *T1, Type *T2) {
assert(isa<IntegerType>(T1) && isa<IntegerType>(T2));
if (T1->getPrimitiveSizeInBits() < T2->getPrimitiveSizeInBits())
return T2;
else
return T1;
}
Value *IslExprBuilder::createOpUnary(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_op_type(Expr) == isl_ast_op_minus &&
"Unsupported unary operation");
Value *V;
Type *MaxType = getType(Expr);
assert(MaxType->isIntegerTy() &&
"Unary expressions can only be created for integer types");
V = create(isl_ast_expr_get_op_arg(Expr, 0));
MaxType = getWidestType(MaxType, V->getType());
if (MaxType != V->getType())
V = Builder.CreateSExt(V, MaxType);
isl_ast_expr_free(Expr);
return Builder.CreateNSWNeg(V);
}
Value *IslExprBuilder::createOpNAry(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_op &&
"isl ast expression not of type isl_ast_op");
assert(isl_ast_expr_get_op_n_arg(Expr) >= 2 &&
"We need at least two operands in an n-ary operation");
Value *V;
V = create(isl_ast_expr_get_op_arg(Expr, 0));
for (int i = 0; i < isl_ast_expr_get_op_n_arg(Expr); ++i) {
Value *OpV;
OpV = create(isl_ast_expr_get_op_arg(Expr, i));
Type *Ty = getWidestType(V->getType(), OpV->getType());
if (Ty != OpV->getType())
OpV = Builder.CreateSExt(OpV, Ty);
if (Ty != V->getType())
V = Builder.CreateSExt(V, Ty);
switch (isl_ast_expr_get_op_type(Expr)) {
default:
llvm_unreachable("This is no n-ary isl ast expression");
case isl_ast_op_max: {
Value *Cmp = Builder.CreateICmpSGT(V, OpV);
V = Builder.CreateSelect(Cmp, V, OpV);
continue;
}
case isl_ast_op_min: {
Value *Cmp = Builder.CreateICmpSLT(V, OpV);
V = Builder.CreateSelect(Cmp, V, OpV);
continue;
}
}
}
// TODO: We can truncate the result, if it fits into a smaller type. This can
// help in cases where we have larger operands (e.g. i67) but the result is
// known to fit into i64. Without the truncation, the larger i67 type may
// force all subsequent operations to be performed on a non-native type.
isl_ast_expr_free(Expr);
return V;
}
Value *IslExprBuilder::createAccessAddress(isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_op &&
"isl ast expression not of type isl_ast_op");
assert(isl_ast_expr_get_op_type(Expr) == isl_ast_op_access &&
"not an access isl ast expression");
assert(isl_ast_expr_get_op_n_arg(Expr) >= 2 &&
"We need at least two operands to create a member access.");
Value *Base, *IndexOp, *Access;
isl_ast_expr *BaseExpr;
isl_id *BaseId;
BaseExpr = isl_ast_expr_get_op_arg(Expr, 0);
BaseId = isl_ast_expr_get_id(BaseExpr);
isl_ast_expr_free(BaseExpr);
const ScopArrayInfo *SAI = ScopArrayInfo::getFromId(BaseId);
Base = SAI->getBasePtr();
if (auto NewBase = GlobalMap.lookup(Base))
Base = NewBase;
assert(Base->getType()->isPointerTy() && "Access base should be a pointer");
StringRef BaseName = Base->getName();
auto PointerTy = PointerType::get(SAI->getElementType(),
Base->getType()->getPointerAddressSpace());
if (Base->getType() != PointerTy) {
Base =
Builder.CreateBitCast(Base, PointerTy, "polly.access.cast." + BaseName);
}
IndexOp = nullptr;
for (unsigned u = 1, e = isl_ast_expr_get_op_n_arg(Expr); u < e; u++) {
Value *NextIndex = create(isl_ast_expr_get_op_arg(Expr, u));
assert(NextIndex->getType()->isIntegerTy() &&
"Access index should be an integer");
if (!IndexOp) {
IndexOp = NextIndex;
} else {
Type *Ty = getWidestType(NextIndex->getType(), IndexOp->getType());
if (Ty != NextIndex->getType())
NextIndex = Builder.CreateIntCast(NextIndex, Ty, true);
if (Ty != IndexOp->getType())
IndexOp = Builder.CreateIntCast(IndexOp, Ty, true);
IndexOp =
Builder.CreateAdd(IndexOp, NextIndex, "polly.access.add." + BaseName);
}
// For every but the last dimension multiply the size, for the last
// dimension we can exit the loop.
if (u + 1 >= e)
break;
const SCEV *DimSCEV = SAI->getDimensionSize(u);
llvm::ValueToValueMap Map(GlobalMap.begin(), GlobalMap.end());
DimSCEV = SCEVParameterRewriter::rewrite(DimSCEV, SE, Map);
Value *DimSize =
expandCodeFor(S, SE, DL, "polly", DimSCEV, DimSCEV->getType(),
&*Builder.GetInsertPoint());
Type *Ty = getWidestType(DimSize->getType(), IndexOp->getType());
if (Ty != IndexOp->getType())
IndexOp = Builder.CreateSExtOrTrunc(IndexOp, Ty,
"polly.access.sext." + BaseName);
if (Ty != DimSize->getType())
DimSize = Builder.CreateSExtOrTrunc(DimSize, Ty,
"polly.access.sext." + BaseName);
IndexOp =
Builder.CreateMul(IndexOp, DimSize, "polly.access.mul." + BaseName);
}
Access = Builder.CreateGEP(Base, IndexOp, "polly.access." + BaseName);
isl_ast_expr_free(Expr);
return Access;
}
Value *IslExprBuilder::createOpAccess(isl_ast_expr *Expr) {
Value *Addr = createAccessAddress(Expr);
assert(Addr && "Could not create op access address");
return Builder.CreateLoad(Addr, Addr->getName() + ".load");
}
Value *IslExprBuilder::createOpBin(__isl_take isl_ast_expr *Expr) {
Value *LHS, *RHS, *Res;
Type *MaxType;
isl_ast_op_type OpType;
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_op &&
"isl ast expression not of type isl_ast_op");
assert(isl_ast_expr_get_op_n_arg(Expr) == 2 &&
"not a binary isl ast expression");
OpType = isl_ast_expr_get_op_type(Expr);
LHS = create(isl_ast_expr_get_op_arg(Expr, 0));
RHS = create(isl_ast_expr_get_op_arg(Expr, 1));
Type *LHSType = LHS->getType();
Type *RHSType = RHS->getType();
MaxType = getWidestType(LHSType, RHSType);
// Take the result into account when calculating the widest type.
//
// For operations such as '+' the result may require a type larger than
// the type of the individual operands. For other operations such as '/', the
// result type cannot be larger than the type of the individual operand. isl
// does not calculate correct types for these operations and we consequently
// exclude those operations here.
switch (OpType) {
case isl_ast_op_pdiv_q:
case isl_ast_op_pdiv_r:
case isl_ast_op_div:
case isl_ast_op_fdiv_q:
case isl_ast_op_zdiv_r:
// Do nothing
break;
case isl_ast_op_add:
case isl_ast_op_sub:
case isl_ast_op_mul:
MaxType = getWidestType(MaxType, getType(Expr));
break;
default:
llvm_unreachable("This is no binary isl ast expression");
}
if (MaxType != RHS->getType())
RHS = Builder.CreateSExt(RHS, MaxType);
if (MaxType != LHS->getType())
LHS = Builder.CreateSExt(LHS, MaxType);
switch (OpType) {
default:
llvm_unreachable("This is no binary isl ast expression");
case isl_ast_op_add:
Res = Builder.CreateNSWAdd(LHS, RHS);
break;
case isl_ast_op_sub:
Res = Builder.CreateNSWSub(LHS, RHS);
break;
case isl_ast_op_mul:
Res = Builder.CreateNSWMul(LHS, RHS);
break;
case isl_ast_op_div:
Res = Builder.CreateSDiv(LHS, RHS, "pexp.div", true);
break;
case isl_ast_op_pdiv_q: // Dividend is non-negative
Res = Builder.CreateUDiv(LHS, RHS, "pexp.p_div_q");
break;
case isl_ast_op_fdiv_q: { // Round towards -infty
if (auto *Const = dyn_cast<ConstantInt>(RHS)) {
auto &Val = Const->getValue();
if (Val.isPowerOf2() && Val.isNonNegative()) {
Res = Builder.CreateAShr(LHS, Val.ceilLogBase2(), "polly.fdiv_q.shr");
break;
}
}
// TODO: Review code and check that this calculation does not yield
// incorrect overflow in some bordercases.
//
// floord(n,d) ((n < 0) ? (n - d + 1) : n) / d
Value *One = ConstantInt::get(MaxType, 1);
Value *Zero = ConstantInt::get(MaxType, 0);
Value *Sum1 = Builder.CreateSub(LHS, RHS, "pexp.fdiv_q.0");
Value *Sum2 = Builder.CreateAdd(Sum1, One, "pexp.fdiv_q.1");
Value *isNegative = Builder.CreateICmpSLT(LHS, Zero, "pexp.fdiv_q.2");
Value *Dividend =
Builder.CreateSelect(isNegative, Sum2, LHS, "pexp.fdiv_q.3");
Res = Builder.CreateSDiv(Dividend, RHS, "pexp.fdiv_q.4");
break;
}
case isl_ast_op_pdiv_r: // Dividend is non-negative
Res = Builder.CreateURem(LHS, RHS, "pexp.pdiv_r");
break;
case isl_ast_op_zdiv_r: // Result only compared against zero
Res = Builder.CreateURem(LHS, RHS, "pexp.zdiv_r");
break;
}
// TODO: We can truncate the result, if it fits into a smaller type. This can
// help in cases where we have larger operands (e.g. i67) but the result is
// known to fit into i64. Without the truncation, the larger i67 type may
// force all subsequent operations to be performed on a non-native type.
isl_ast_expr_free(Expr);
return Res;
}
Value *IslExprBuilder::createOpSelect(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_op_type(Expr) == isl_ast_op_select &&
"Unsupported unary isl ast expression");
Value *LHS, *RHS, *Cond;
Type *MaxType = getType(Expr);
Cond = create(isl_ast_expr_get_op_arg(Expr, 0));
if (!Cond->getType()->isIntegerTy(1))
Cond = Builder.CreateIsNotNull(Cond);
LHS = create(isl_ast_expr_get_op_arg(Expr, 1));
RHS = create(isl_ast_expr_get_op_arg(Expr, 2));
MaxType = getWidestType(MaxType, LHS->getType());
MaxType = getWidestType(MaxType, RHS->getType());
if (MaxType != RHS->getType())
RHS = Builder.CreateSExt(RHS, MaxType);
if (MaxType != LHS->getType())
LHS = Builder.CreateSExt(LHS, MaxType);
// TODO: Do we want to truncate the result?
isl_ast_expr_free(Expr);
return Builder.CreateSelect(Cond, LHS, RHS);
}
Value *IslExprBuilder::createOpICmp(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_op &&
"Expected an isl_ast_expr_op expression");
Value *LHS, *RHS, *Res;
auto *Op0 = isl_ast_expr_get_op_arg(Expr, 0);
auto *Op1 = isl_ast_expr_get_op_arg(Expr, 1);
bool HasNonAddressOfOperand =
isl_ast_expr_get_type(Op0) != isl_ast_expr_op ||
isl_ast_expr_get_type(Op1) != isl_ast_expr_op ||
isl_ast_expr_get_op_type(Op0) != isl_ast_op_address_of ||
isl_ast_expr_get_op_type(Op1) != isl_ast_op_address_of;
LHS = create(Op0);
RHS = create(Op1);
auto *LHSTy = LHS->getType();
auto *RHSTy = RHS->getType();
bool IsPtrType = LHSTy->isPointerTy() || RHSTy->isPointerTy();
bool UseUnsignedCmp = IsPtrType && !HasNonAddressOfOperand;
auto *PtrAsIntTy = Builder.getIntNTy(DL.getPointerSizeInBits());
if (LHSTy->isPointerTy())
LHS = Builder.CreatePtrToInt(LHS, PtrAsIntTy);
if (RHSTy->isPointerTy())
RHS = Builder.CreatePtrToInt(RHS, PtrAsIntTy);
if (LHS->getType() != RHS->getType()) {
Type *MaxType = LHS->getType();
MaxType = getWidestType(MaxType, RHS->getType());
if (MaxType != RHS->getType())
RHS = Builder.CreateSExt(RHS, MaxType);
if (MaxType != LHS->getType())
LHS = Builder.CreateSExt(LHS, MaxType);
}
isl_ast_op_type OpType = isl_ast_expr_get_op_type(Expr);
assert(OpType >= isl_ast_op_eq && OpType <= isl_ast_op_gt &&
"Unsupported ICmp isl ast expression");
assert(isl_ast_op_eq + 4 == isl_ast_op_gt &&
"Isl ast op type interface changed");
CmpInst::Predicate Predicates[5][2] = {
{CmpInst::ICMP_EQ, CmpInst::ICMP_EQ},
{CmpInst::ICMP_SLE, CmpInst::ICMP_ULE},
{CmpInst::ICMP_SLT, CmpInst::ICMP_ULT},
{CmpInst::ICMP_SGE, CmpInst::ICMP_UGE},
{CmpInst::ICMP_SGT, CmpInst::ICMP_UGT},
};
Res = Builder.CreateICmp(Predicates[OpType - isl_ast_op_eq][UseUnsignedCmp],
LHS, RHS);
isl_ast_expr_free(Expr);
return Res;
}
Value *IslExprBuilder::createOpBoolean(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_op &&
"Expected an isl_ast_expr_op expression");
Value *LHS, *RHS, *Res;
isl_ast_op_type OpType;
OpType = isl_ast_expr_get_op_type(Expr);
assert((OpType == isl_ast_op_and || OpType == isl_ast_op_or) &&
"Unsupported isl_ast_op_type");
LHS = create(isl_ast_expr_get_op_arg(Expr, 0));
RHS = create(isl_ast_expr_get_op_arg(Expr, 1));
// Even though the isl pretty printer prints the expressions as 'exp && exp'
// or 'exp || exp', we actually code generate the bitwise expressions
// 'exp & exp' or 'exp | exp'. This forces the evaluation of both branches,
// but it is, due to the use of i1 types, otherwise equivalent. The reason
// to go for bitwise operations is, that we assume the reduced control flow
// will outweight the overhead introduced by evaluating unneeded expressions.
// The isl code generation currently does not take advantage of the fact that
// the expression after an '||' or '&&' is in some cases not evaluated.
// Evaluating it anyways does not cause any undefined behaviour.
//
// TODO: Document in isl itself, that the unconditionally evaluating the
// second part of '||' or '&&' expressions is safe.
if (!LHS->getType()->isIntegerTy(1))
LHS = Builder.CreateIsNotNull(LHS);
if (!RHS->getType()->isIntegerTy(1))
RHS = Builder.CreateIsNotNull(RHS);
switch (OpType) {
default:
llvm_unreachable("Unsupported boolean expression");
case isl_ast_op_and:
Res = Builder.CreateAnd(LHS, RHS);
break;
case isl_ast_op_or:
Res = Builder.CreateOr(LHS, RHS);
break;
}
isl_ast_expr_free(Expr);
return Res;
}
Value *
IslExprBuilder::createOpBooleanConditional(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_op &&
"Expected an isl_ast_expr_op expression");
Value *LHS, *RHS;
isl_ast_op_type OpType;
Function *F = Builder.GetInsertBlock()->getParent();
LLVMContext &Context = F->getContext();
OpType = isl_ast_expr_get_op_type(Expr);
assert((OpType == isl_ast_op_and_then || OpType == isl_ast_op_or_else) &&
"Unsupported isl_ast_op_type");
auto InsertBB = Builder.GetInsertBlock();
auto InsertPoint = Builder.GetInsertPoint();
auto NextBB = SplitBlock(InsertBB, &*InsertPoint, &DT, &LI);
BasicBlock *CondBB = BasicBlock::Create(Context, "polly.cond", F);
LI.changeLoopFor(CondBB, LI.getLoopFor(InsertBB));
DT.addNewBlock(CondBB, InsertBB);
InsertBB->getTerminator()->eraseFromParent();
Builder.SetInsertPoint(InsertBB);
auto BR = Builder.CreateCondBr(Builder.getTrue(), NextBB, CondBB);
Builder.SetInsertPoint(CondBB);
Builder.CreateBr(NextBB);
Builder.SetInsertPoint(InsertBB->getTerminator());
LHS = create(isl_ast_expr_get_op_arg(Expr, 0));
if (!LHS->getType()->isIntegerTy(1))
LHS = Builder.CreateIsNotNull(LHS);
auto LeftBB = Builder.GetInsertBlock();
if (OpType == isl_ast_op_and || OpType == isl_ast_op_and_then)
BR->setCondition(Builder.CreateNeg(LHS));
else
BR->setCondition(LHS);
Builder.SetInsertPoint(CondBB->getTerminator());
RHS = create(isl_ast_expr_get_op_arg(Expr, 1));
if (!RHS->getType()->isIntegerTy(1))
RHS = Builder.CreateIsNotNull(RHS);
auto RightBB = Builder.GetInsertBlock();
Builder.SetInsertPoint(NextBB->getTerminator());
auto PHI = Builder.CreatePHI(Builder.getInt1Ty(), 2);
PHI->addIncoming(OpType == isl_ast_op_and_then ? Builder.getFalse()
: Builder.getTrue(),
LeftBB);
PHI->addIncoming(RHS, RightBB);
isl_ast_expr_free(Expr);
return PHI;
}
Value *IslExprBuilder::createOp(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_op &&
"Expression not of type isl_ast_expr_op");
switch (isl_ast_expr_get_op_type(Expr)) {
case isl_ast_op_error:
case isl_ast_op_cond:
case isl_ast_op_call:
case isl_ast_op_member:
llvm_unreachable("Unsupported isl ast expression");
case isl_ast_op_access:
return createOpAccess(Expr);
case isl_ast_op_max:
case isl_ast_op_min:
return createOpNAry(Expr);
case isl_ast_op_add:
case isl_ast_op_sub:
case isl_ast_op_mul:
case isl_ast_op_div:
case isl_ast_op_fdiv_q: // Round towards -infty
case isl_ast_op_pdiv_q: // Dividend is non-negative
case isl_ast_op_pdiv_r: // Dividend is non-negative
case isl_ast_op_zdiv_r: // Result only compared against zero
return createOpBin(Expr);
case isl_ast_op_minus:
return createOpUnary(Expr);
case isl_ast_op_select:
return createOpSelect(Expr);
case isl_ast_op_and:
case isl_ast_op_or:
return createOpBoolean(Expr);
case isl_ast_op_and_then:
case isl_ast_op_or_else:
return createOpBooleanConditional(Expr);
case isl_ast_op_eq:
case isl_ast_op_le:
case isl_ast_op_lt:
case isl_ast_op_ge:
case isl_ast_op_gt:
return createOpICmp(Expr);
case isl_ast_op_address_of:
return createOpAddressOf(Expr);
}
llvm_unreachable("Unsupported isl_ast_expr_op kind.");
}
Value *IslExprBuilder::createOpAddressOf(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_op &&
"Expected an isl_ast_expr_op expression.");
assert(isl_ast_expr_get_op_n_arg(Expr) == 1 && "Address of should be unary.");
isl_ast_expr *Op = isl_ast_expr_get_op_arg(Expr, 0);
assert(isl_ast_expr_get_type(Op) == isl_ast_expr_op &&
"Expected address of operator to be an isl_ast_expr_op expression.");
assert(isl_ast_expr_get_op_type(Op) == isl_ast_op_access &&
"Expected address of operator to be an access expression.");
Value *V = createAccessAddress(Op);
isl_ast_expr_free(Expr);
return V;
}
Value *IslExprBuilder::createId(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_id &&
"Expression not of type isl_ast_expr_ident");
isl_id *Id;
Value *V;
Id = isl_ast_expr_get_id(Expr);
assert(IDToValue.count(Id) && "Identifier not found");
V = IDToValue[Id];
if (!V)
V = UndefValue::get(getType(Expr));
if (V->getType()->isPointerTy())
V = Builder.CreatePtrToInt(V, Builder.getIntNTy(DL.getPointerSizeInBits()));
assert(V && "Unknown parameter id found");
isl_id_free(Id);
isl_ast_expr_free(Expr);
return V;
}
IntegerType *IslExprBuilder::getType(__isl_keep isl_ast_expr *Expr) {
// XXX: We assume i64 is large enough. This is often true, but in general
// incorrect. Also, on 32bit architectures, it would be beneficial to
// use a smaller type. We can and should directly derive this information
// during code generation.
return IntegerType::get(Builder.getContext(), 64);
}
Value *IslExprBuilder::createInt(__isl_take isl_ast_expr *Expr) {
assert(isl_ast_expr_get_type(Expr) == isl_ast_expr_int &&
"Expression not of type isl_ast_expr_int");
isl_val *Val;
Value *V;
APInt APValue;
IntegerType *T;
Val = isl_ast_expr_get_val(Expr);
APValue = APIntFromVal(Val);
auto BitWidth = APValue.getBitWidth();
if (BitWidth <= 64)
T = getType(Expr);
else
T = Builder.getIntNTy(BitWidth);
APValue = APValue.sextOrSelf(T->getBitWidth());
V = ConstantInt::get(T, APValue);
isl_ast_expr_free(Expr);
return V;
}
Value *IslExprBuilder::create(__isl_take isl_ast_expr *Expr) {
switch (isl_ast_expr_get_type(Expr)) {
case isl_ast_expr_error:
llvm_unreachable("Code generation error");
case isl_ast_expr_op:
return createOp(Expr);
case isl_ast_expr_id:
return createId(Expr);
case isl_ast_expr_int:
return createInt(Expr);
}
llvm_unreachable("Unexpected enum value");
}
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