6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-28 19:31:58 +00:00
Code Issues Projects Releases Wiki Activity

Add 'umax' similar to 'smax' SCEV. Closes PR2003.

Browse Source 
Parse reversed smax and umax as smin and umin and express them with negative
or binary-not SCEVs (which are really just subtract under the hood).

Parse 'xor %x, -1' as (-1 - %x).

Remove dead code (ConstantInt::get always returns a ConstantInt).

Don't use getIntegerSCEV(-1, Ty). The first value is an int, then it gets
passed into a uint64_t. Instead, create the -1 directly from
ConstantInt::getAllOnesValue().


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47360 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2008-02-20 06:48:22 +00:00
parent 19fc1d3742
commit 3e63076980
7 changed files with 209 additions and 49 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/llvm/Analysis/ScalarEvolution.h
View File

@ -237,12 +237,18 @@ namespace llvm {
}
SCEVHandle getSMaxExpr(const SCEVHandle &LHS, const SCEVHandle &RHS);
SCEVHandle getSMaxExpr(std::vector<SCEVHandle> Operands);
SCEVHandle getUMaxExpr(const SCEVHandle &LHS, const SCEVHandle &RHS);
SCEVHandle getUMaxExpr(std::vector<SCEVHandle> Operands);
SCEVHandle getUnknown(Value *V);
/// getNegativeSCEV - Return the SCEV object corresponding to -V.
///
SCEVHandle getNegativeSCEV(const SCEVHandle &V);
/// getNotSCEV - Return the SCEV object corresponding to ~V.
///
SCEVHandle getNotSCEV(const SCEVHandle &V);
/// getMinusSCEV - Return LHS-RHS.
///
SCEVHandle getMinusSCEV(const SCEVHandle &LHS,

2
include/llvm/Analysis/ScalarEvolutionExpander.h
View File

@ -136,6 +136,8 @@ namespace llvm {
Value *visitSMaxExpr(SCEVSMaxExpr *S);
Value *visitUMaxExpr(SCEVUMaxExpr *S);
Value *visitUnknown(SCEVUnknown *S) {
return S->getValue();
}

30
include/llvm/Analysis/ScalarEvolutionExpressions.h
View File

@ -25,7 +25,8 @@ namespace llvm {
// These should be ordered in terms of increasing complexity to make the
// folders simpler.
scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
scUDivExpr, scAddRecExpr, scSMaxExpr, scUnknown, scCouldNotCompute
scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr, scUnknown,
scCouldNotCompute
};
//===--------------------------------------------------------------------===//
@ -275,7 +276,8 @@ namespace llvm {
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scAddExpr ||
S->getSCEVType() == scMulExpr ||
S->getSCEVType() == scSMaxExpr;
S->getSCEVType() == scSMaxExpr ||
S->getSCEVType() == scUMaxExpr;
}
};
@ -482,6 +484,27 @@ namespace llvm {
};
//===--------------------------------------------------------------------===//
/// SCEVUMaxExpr - This class represents an unsigned maximum selection.
///
class SCEVUMaxExpr : public SCEVCommutativeExpr {
friend class ScalarEvolution;
explicit SCEVUMaxExpr(const std::vector<SCEVHandle> &ops)
: SCEVCommutativeExpr(scUMaxExpr, ops) {
}
public:
virtual const char *getOperationStr() const { return " umax "; }
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVUMaxExpr *S) { return true; }
static inline bool classof(const SCEV *S) {
return S->getSCEVType() == scUMaxExpr;
}
};
//===--------------------------------------------------------------------===//
/// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV
/// value, and only represent it as it's LLVM Value. This is the "bottom"
@ -546,6 +569,8 @@ namespace llvm {
return ((SC*)this)->visitAddRecExpr((SCEVAddRecExpr*)S);
case scSMaxExpr:
return ((SC*)this)->visitSMaxExpr((SCEVSMaxExpr*)S);
case scUMaxExpr:
return ((SC*)this)->visitUMaxExpr((SCEVUMaxExpr*)S);
case scUnknown:
return ((SC*)this)->visitUnknown((SCEVUnknown*)S);
case scCouldNotCompute:
@ -565,4 +590,3 @@ namespace llvm {
}
#endif

190
lib/Analysis/ScalarEvolution.cpp
View File

@ -320,6 +320,8 @@ replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
return SE.getMulExpr(NewOps);
else if (isa<SCEVSMaxExpr>(this))
return SE.getSMaxExpr(NewOps);
else if (isa<SCEVUMaxExpr>(this))
return SE.getUMaxExpr(NewOps);
else
assert(0 && "Unknown commutative expr!");
}
@ -520,7 +522,16 @@ SCEVHandle ScalarEvolution::getNegativeSCEV(const SCEVHandle &V) {
if (SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
return getUnknown(ConstantExpr::getNeg(VC->getValue()));
return getMulExpr(V, getIntegerSCEV(-1, V->getType()));
return getMulExpr(V, getUnknown(ConstantInt::getAllOnesValue(V->getType())));
}
/// getNotSCEV - Return a SCEV corresponding to ~V = -1-V
SCEVHandle ScalarEvolution::getNotSCEV(const SCEVHandle &V) {
if (SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
return getUnknown(ConstantExpr::getNot(VC->getValue()));
SCEVHandle AllOnes = getUnknown(ConstantInt::getAllOnesValue(V->getType()));
return getMinusSCEV(AllOnes, V);
}
/// getMinusSCEV - Return a SCEV corresponding to LHS - RHS.
@ -709,19 +720,12 @@ SCEVHandle ScalarEvolution::getAddExpr(std::vector<SCEVHandle> &Ops) {
assert(Idx < Ops.size());
while (SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
// We found two constants, fold them together!
Constant *Fold = ConstantInt::get(LHSC->getValue()->getValue() +
RHSC->getValue()->getValue());
if (ConstantInt *CI = dyn_cast<ConstantInt>(Fold)) {
Ops[0] = getConstant(CI);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
} else {
// If we couldn't fold the expression, move to the next constant. Note
// that this is impossible to happen in practice because we always
// constant fold constant ints to constant ints.
++Idx;
}
ConstantInt *Fold = ConstantInt::get(LHSC->getValue()->getValue() +
RHSC->getValue()->getValue());
Ops[0] = getConstant(Fold);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
}
// If we are left with a constant zero being added, strip it off.
@ -950,19 +954,12 @@ SCEVHandle ScalarEvolution::getMulExpr(std::vector<SCEVHandle> &Ops) {
++Idx;
while (SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
// We found two constants, fold them together!
Constant *Fold = ConstantInt::get(LHSC->getValue()->getValue() *
RHSC->getValue()->getValue());
if (ConstantInt *CI = dyn_cast<ConstantInt>(Fold)) {
Ops[0] = getConstant(CI);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
} else {
// If we couldn't fold the expression, move to the next constant. Note
// that this is impossible to happen in practice because we always
// constant fold constant ints to constant ints.
++Idx;
}
ConstantInt *Fold = ConstantInt::get(LHSC->getValue()->getValue() *
RHSC->getValue()->getValue());
Ops[0] = getConstant(Fold);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
}
// If we are left with a constant one being multiplied, strip it off.
@ -1170,20 +1167,13 @@ SCEVHandle ScalarEvolution::getSMaxExpr(std::vector<SCEVHandle> Ops) {
assert(Idx < Ops.size());
while (SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
// We found two constants, fold them together!
Constant *Fold = ConstantInt::get(
ConstantInt *Fold = ConstantInt::get(
APIntOps::smax(LHSC->getValue()->getValue(),
RHSC->getValue()->getValue()));
if (ConstantInt *CI = dyn_cast<ConstantInt>(Fold)) {
Ops[0] = getConstant(CI);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
} else {
// If we couldn't fold the expression, move to the next constant. Note
// that this is impossible to happen in practice because we always
// constant fold constant ints to constant ints.
++Idx;
}
Ops[0] = getConstant(Fold);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
}
// If we are left with a constant -inf, strip it off.
@ -1226,7 +1216,7 @@ SCEVHandle ScalarEvolution::getSMaxExpr(std::vector<SCEVHandle> Ops) {
assert(!Ops.empty() && "Reduced smax down to nothing!");
// Okay, it looks like we really DO need an add expr. Check to see if we
// Okay, it looks like we really DO need an smax expr. Check to see if we
// already have one, otherwise create a new one.
std::vector<SCEV*> SCEVOps(Ops.begin(), Ops.end());
SCEVCommutativeExpr *&Result = (*SCEVCommExprs)[std::make_pair(scSMaxExpr,
@ -1235,6 +1225,86 @@ SCEVHandle ScalarEvolution::getSMaxExpr(std::vector<SCEVHandle> Ops) {
return Result;
}
SCEVHandle ScalarEvolution::getUMaxExpr(const SCEVHandle &LHS,
const SCEVHandle &RHS) {
std::vector<SCEVHandle> Ops;
Ops.push_back(LHS);
Ops.push_back(RHS);
return getUMaxExpr(Ops);
}
SCEVHandle ScalarEvolution::getUMaxExpr(std::vector<SCEVHandle> Ops) {
assert(!Ops.empty() && "Cannot get empty umax!");
if (Ops.size() == 1) return Ops[0];
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops);
// If there are any constants, fold them together.
unsigned Idx = 0;
if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
++Idx;
assert(Idx < Ops.size());
while (SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
// We found two constants, fold them together!
ConstantInt *Fold = ConstantInt::get(
APIntOps::umax(LHSC->getValue()->getValue(),
RHSC->getValue()->getValue()));
Ops[0] = getConstant(Fold);
Ops.erase(Ops.begin()+1); // Erase the folded element
if (Ops.size() == 1) return Ops[0];
LHSC = cast<SCEVConstant>(Ops[0]);
}
// If we are left with a constant zero, strip it off.
if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
Ops.erase(Ops.begin());
--Idx;
}
}
if (Ops.size() == 1) return Ops[0];
// Find the first UMax
while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr)
++Idx;
// Check to see if one of the operands is a UMax. If so, expand its operands
// onto our operand list, and recurse to simplify.
if (Idx < Ops.size()) {
bool DeletedUMax = false;
while (SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) {
Ops.insert(Ops.end(), UMax->op_begin(), UMax->op_end());
Ops.erase(Ops.begin()+Idx);
DeletedUMax = true;
}
if (DeletedUMax)
return getUMaxExpr(Ops);
}
// Okay, check to see if the same value occurs in the operand list twice. If
// so, delete one. Since we sorted the list, these values are required to
// be adjacent.
for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
if (Ops[i] == Ops[i+1]) { // X umax Y umax Y --> X umax Y
Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
--i; --e;
}
if (Ops.size() == 1) return Ops[0];
assert(!Ops.empty() && "Reduced umax down to nothing!");
// Okay, it looks like we really DO need a umax expr. Check to see if we
// already have one, otherwise create a new one.
std::vector<SCEV*> SCEVOps(Ops.begin(), Ops.end());
SCEVCommutativeExpr *&Result = (*SCEVCommExprs)[std::make_pair(scUMaxExpr,
SCEVOps)];
if (Result == 0) Result = new SCEVUMaxExpr(Ops);
return Result;
}
SCEVHandle ScalarEvolution::getUnknown(Value *V) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
return getConstant(CI);
@ -1606,6 +1676,14 @@ static uint32_t GetMinTrailingZeros(SCEVHandle S) {
return MinOpRes;
}
if (SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
// The result is the min of all operands results.
uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
return MinOpRes;
}
// SCEVUDivExpr, SCEVUnknown
return 0;
}
@ -1653,6 +1731,8 @@ SCEVHandle ScalarEvolutionsImpl::createSCEV(Value *V) {
if (CI->getValue().isSignBit())
return SE.getAddExpr(getSCEV(I->getOperand(0)),
getSCEV(I->getOperand(1)));
else if (CI->isAllOnesValue())
return SE.getNotSCEV(getSCEV(I->getOperand(0)));
}
break;
@ -1686,7 +1766,8 @@ SCEVHandle ScalarEvolutionsImpl::createSCEV(Value *V) {
return createNodeForPHI(cast<PHINode>(I));
case Instruction::Select:
// This could be an SCEVSMax that was lowered earlier. Try to recover it.
// This could be a smax or umax that was lowered earlier.
// Try to recover it.
if (ICmpInst *ICI = dyn_cast<ICmpInst>(I->getOperand(0))) {
Value *LHS = ICI->getOperand(0);
Value *RHS = ICI->getOperand(1);
@ -1699,6 +1780,25 @@ SCEVHandle ScalarEvolutionsImpl::createSCEV(Value *V) {
case ICmpInst::ICMP_SGE:
if (LHS == I->getOperand(1) && RHS == I->getOperand(2))
return SE.getSMaxExpr(getSCEV(LHS), getSCEV(RHS));
else if (LHS == I->getOperand(2) && RHS == I->getOperand(1))
// -smax(-x, -y) == smin(x, y).
return SE.getNegativeSCEV(SE.getSMaxExpr(
SE.getNegativeSCEV(getSCEV(LHS)),
SE.getNegativeSCEV(getSCEV(RHS))));
break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
std::swap(LHS, RHS);
// fall through
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
if (LHS == I->getOperand(1) && RHS == I->getOperand(2))
return SE.getUMaxExpr(getSCEV(LHS), getSCEV(RHS));
else if (LHS == I->getOperand(2) && RHS == I->getOperand(1))
// ~umax(~x, ~y) == umin(x, y)
return SE.getNotSCEV(SE.getUMaxExpr(SE.getNotSCEV(getSCEV(LHS)),
SE.getNotSCEV(getSCEV(RHS))));
break;
default:
break;
}
@ -2212,7 +2312,7 @@ SCEVHandle ScalarEvolutionsImpl::getSCEVAtScope(SCEV *V, const Loop *L) {
if (isa<SCEVConstant>(V)) return V;
// If this instruction is evolves from a constant-evolving PHI, compute the
// If this instruction is evolved from a constant-evolving PHI, compute the
// exit value from the loop without using SCEVs.
if (SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
@ -2308,6 +2408,8 @@ SCEVHandle ScalarEvolutionsImpl::getSCEVAtScope(SCEV *V, const Loop *L) {
return SE.getMulExpr(NewOps);
if (isa<SCEVSMaxExpr>(Comm))
return SE.getSMaxExpr(NewOps);
if (isa<SCEVUMaxExpr>(Comm))
return SE.getUMaxExpr(NewOps);
assert(0 && "Unknown commutative SCEV type!");
}
}
@ -2540,8 +2642,8 @@ HowManyLessThans(SCEV *LHS, SCEV *RHS, const Loop *L, bool isSigned) {
// Then, we get the value of the LHS in the first iteration in which the
// above condition doesn't hold. This equals to max(m,n).
// FIXME (PR2003): we should have an "umax" operator as well.
SCEVHandle End = isSigned ? SE.getSMaxExpr(RHS,Start) : (SCEVHandle)RHS;
SCEVHandle End = isSigned ? SE.getSMaxExpr(RHS, Start)
: SE.getUMaxExpr(RHS, Start);
// Finally, we subtract these two values to get the number of times the
// backedge is executed: max(m,n)-n.

11
lib/Analysis/ScalarEvolutionExpander.cpp
View File

@ -220,6 +220,16 @@ Value *SCEVExpander::visitSMaxExpr(SCEVSMaxExpr *S) {
return LHS;
}
Value *SCEVExpander::visitUMaxExpr(SCEVUMaxExpr *S) {
Value *LHS = expand(S->getOperand(0));
for (unsigned i = 1; i < S->getNumOperands(); ++i) {
Value *RHS = expand(S->getOperand(i));
Value *ICmp = new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS, "tmp", InsertPt);
LHS = new SelectInst(ICmp, LHS, RHS, "umax", InsertPt);
}
return LHS;
}
Value *SCEVExpander::expand(SCEV *S) {
// Check to see if we already expanded this.
std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
@ -230,4 +240,3 @@ Value *SCEVExpander::expand(SCEV *S) {
InsertedExpressions[S] = V;
return V;
}

2
test/Analysis/ScalarEvolution/2007-08-06-Unsigned.ll
View File

@ -1,4 +1,4 @@
; RUN: llvm-as < %s | opt -scalar-evolution -analyze | grep {Loop bb: ( -1 + ( -1 \\* %x) + %y) iterations!}
; RUN: llvm-as < %s | opt -scalar-evolution -analyze | grep {Loop bb: ( -1 + ( -1 \\* %x) + (( 1 + %x) umax %y)) iterations!}
; PR1597
define i32 @f(i32 %x, i32 %y) {

17
test/Analysis/ScalarEvolution/2008-02-15-UMax.ll Normal file
View File

@ -0,0 +1,17 @@
; RUN: llvm-as < %s | opt -analyze -scalar-evolution | grep umax
; PR2003
define i32 @foo(i32 %n) {
entry:
br label %header
header:
%i = phi i32 [ 100, %entry ], [ %i.inc, %next ]
%cond = icmp ult i32 %i, %n
br i1 %cond, label %next, label %return
next:
%i.inc = add i32 %i, 1
br label %header
return:
ret i32 %i
}