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Fix indenting, remove tabs.

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Learn from sext and zext. The destination value falls within the range of the
source type.

Generalize properties regarding constant ints.

Get smarter about marking blocks as unreachable. If 1 >= 2 in order for this
block to execute, then it isn't reachable.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33889 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky
2007-02-04 23:43:05 +00:00
parent 13b7d3d499
commit 4535175328
1 changed files with 90 additions and 32 deletions
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68
lib/Transforms/Scalar/PredicateSimplifier.cpp
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@@ -52,7 +52,7 @@
// responsible for analyzing the variable and seeing what new inferences
// can be made from each property. For example:
//
// %P = setne int* %ptr, null
// %P = icmp ne int* %ptr, null
// %a = and bool %P, %Q
// br bool %a label %cond_true, label %cond_false
//
@@ -868,7 +868,7 @@ namespace {
if (n1) assert(V1 == IG.node(n1)->getValue() && "Value isn't canonical.");
if (n2) assert(V2 == IG.node(n2)->getValue() && "Value isn't canonical.");
if (compare(V2, V1)) { std::swap(V1, V2); std::swap(n1, n2); }
assert(!compare(V2, V1) && "Please order parameters to makeEqual.");
assert(!isa<Constant>(V2) && "Tried to remove a constant.");
@@ -1398,11 +1398,23 @@ namespace {
DEBUG(IG.dump());
// TODO: actually check the constants and add to UB.
if (isa<Constant>(O.LHS) && isa<Constant>(O.RHS)) {
// If they're both Constant, skip it. Check for contradiction and mark
// the BB as unreachable if so.
if (Constant *CI_L = dyn_cast<Constant>(O.LHS)) {
if (Constant *CI_R = dyn_cast<Constant>(O.RHS)) {
if (ConstantExpr::getCompare(O.Op, CI_L, CI_R) ==
ConstantInt::getFalse())
UB.mark(TopBB);
WorkList.pop_front();
continue;
}
}
if (compare(O.RHS, O.LHS)) {
std::swap(O.LHS, O.RHS);
O.Op = ICmpInst::getSwappedPredicate(O.Op);
}
if (O.Op == ICmpInst::ICMP_EQ) {
if (!makeEqual(O.LHS, O.RHS))
@@ -1416,7 +1428,7 @@ namespace {
UB.mark(TopBB);
} else {
if (isRelatedBy(O.LHS, O.RHS, ICmpInst::getInversePredicate(O.Op))){
DOUT << "inequality contradiction!\n";
UB.mark(TopBB);
WorkList.pop_front();
continue;
}
@@ -1438,6 +1450,31 @@ namespace {
continue;
}
// Generalize %x u> -10 to %x > -10.
if (ConstantInt *CI = dyn_cast<ConstantInt>(O.RHS)) {
// xform doesn't apply to i1
if (CI->getType()->getBitWidth() > 1) {
if (LV == SLT && CI->getSExtValue() < 0) {
// i8 %x s< -5 implies %x < -5 and %x u> 127
const IntegerType *Ty = CI->getType();
LV = LT;
add(O.LHS, ConstantInt::get(Ty, Ty->getBitMask() >> 1),
ICmpInst::ICMP_UGT);
} else if (LV == SGT && CI->getSExtValue() >= 0) {
// i8 %x s> 5 implies %x > 5 and %x u< 128
const IntegerType *Ty = CI->getType();
LV = LT;
add(O.LHS, ConstantInt::get(Ty, 1 << Ty->getBitWidth()),
ICmpInst::ICMP_ULT);
} else if (CI->getSExtValue() >= 0) {
if (LV == ULT || LV == SLT) LV = LT;
if (LV == UGT || LV == SGT) LV = GT;
}
}
}
IG.addInequality(n1, n2, Top, LV);
if (Instruction *I1 = dyn_cast<Instruction>(O.LHS)) {
@@ -1531,6 +1568,9 @@ namespace {
void visitLoadInst(LoadInst &LI);
void visitStoreInst(StoreInst &SI);
void visitSExtInst(SExtInst &SI);
void visitZExtInst(ZExtInst &ZI);
void visitBinaryOperator(BinaryOperator &BO);
};
@@ -1730,6 +1770,24 @@ namespace {
VRP.solve();
}
void PredicateSimplifier::Forwards::visitSExtInst(SExtInst &SI) {
VRPSolver VRP(IG, UB, PS->Forest, PS->modified, &SI);
const IntegerType *Ty = cast<IntegerType>(SI.getSrcTy());
VRP.add(ConstantInt::get(SI.getDestTy(), ~(Ty->getBitMask() >> 1)),
&SI, ICmpInst::ICMP_SLE);
VRP.add(ConstantInt::get(SI.getDestTy(), (1 << (Ty->getBitWidth()-1)) - 1),
&SI, ICmpInst::ICMP_SGE);
VRP.solve();
}
void PredicateSimplifier::Forwards::visitZExtInst(ZExtInst &ZI) {
VRPSolver VRP(IG, UB, PS->Forest, PS->modified, &ZI);
const IntegerType *Ty = cast<IntegerType>(ZI.getSrcTy());
VRP.add(ConstantInt::get(ZI.getDestTy(), Ty->getBitMask()),
&ZI, ICmpInst::ICMP_UGE);
VRP.solve();
}
void PredicateSimplifier::Forwards::visitBinaryOperator(BinaryOperator &BO) {
Instruction::BinaryOps ops = BO.getOpcode();