Temporarily revert "Recommit r328307: [IPSCCP] Use constant range information for comparisons of parameters." as it's causing miscompiles.
A testcase was provided in the original review thread.
This reverts commit r336098.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336877 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index 6f3d798..6d674f4 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -69,6 +69,8 @@
STATISTIC(IPNumInstRemoved, "Number of instructions removed by IPSCCP");
STATISTIC(IPNumArgsElimed ,"Number of arguments constant propagated by IPSCCP");
STATISTIC(IPNumGlobalConst, "Number of globals found to be constant by IPSCCP");
+STATISTIC(IPNumRangeInfoUsed, "Number of times constant range info was used by"
+ "IPSCCP");
namespace {
@@ -337,13 +339,20 @@
return StructValues;
}
- const LatticeVal &getLatticeValueFor(Value *V) const {
+ ValueLatticeElement getLatticeValueFor(Value *V) {
assert(!V->getType()->isStructTy() &&
"Should use getStructLatticeValueFor");
- DenseMap<Value *, LatticeVal>::const_iterator I = ValueState.find(V);
- assert(I != ValueState.end() &&
- "V not found in ValueState nor Paramstate map!");
- return I->second;
+ std::pair<DenseMap<Value*, ValueLatticeElement>::iterator, bool>
+ PI = ParamState.insert(std::make_pair(V, ValueLatticeElement()));
+ ValueLatticeElement &LV = PI.first->second;
+ if (PI.second) {
+ DenseMap<Value*, LatticeVal>::const_iterator I = ValueState.find(V);
+ assert(I != ValueState.end() &&
+ "V not found in ValueState nor Paramstate map!");
+ LV = I->second.toValueLattice();
+ }
+
+ return LV;
}
/// getTrackedRetVals - Get the inferred return value map.
@@ -404,16 +413,15 @@
// markConstant - Make a value be marked as "constant". If the value
// is not already a constant, add it to the instruction work list so that
// the users of the instruction are updated later.
- bool markConstant(LatticeVal &IV, Value *V, Constant *C) {
- if (!IV.markConstant(C)) return false;
+ void markConstant(LatticeVal &IV, Value *V, Constant *C) {
+ if (!IV.markConstant(C)) return;
LLVM_DEBUG(dbgs() << "markConstant: " << *C << ": " << *V << '\n');
pushToWorkList(IV, V);
- return true;
}
- bool markConstant(Value *V, Constant *C) {
+ void markConstant(Value *V, Constant *C) {
assert(!V->getType()->isStructTy() && "structs should use mergeInValue");
- return markConstant(ValueState[V], V, C);
+ markConstant(ValueState[V], V, C);
}
void markForcedConstant(Value *V, Constant *C) {
@@ -427,8 +435,8 @@
// markOverdefined - Make a value be marked as "overdefined". If the
// value is not already overdefined, add it to the overdefined instruction
// work list so that the users of the instruction are updated later.
- bool markOverdefined(LatticeVal &IV, Value *V) {
- if (!IV.markOverdefined()) return false;
+ void markOverdefined(LatticeVal &IV, Value *V) {
+ if (!IV.markOverdefined()) return;
LLVM_DEBUG(dbgs() << "markOverdefined: ";
if (auto *F = dyn_cast<Function>(V)) dbgs()
@@ -436,25 +444,23 @@
else dbgs() << *V << '\n');
// Only instructions go on the work list
pushToWorkList(IV, V);
- return true;
}
- bool mergeInValue(LatticeVal &IV, Value *V, LatticeVal MergeWithV) {
+ void mergeInValue(LatticeVal &IV, Value *V, LatticeVal MergeWithV) {
if (IV.isOverdefined() || MergeWithV.isUnknown())
- return false; // Noop.
+ return; // Noop.
if (MergeWithV.isOverdefined())
return markOverdefined(IV, V);
if (IV.isUnknown())
return markConstant(IV, V, MergeWithV.getConstant());
if (IV.getConstant() != MergeWithV.getConstant())
return markOverdefined(IV, V);
- return false;
}
- bool mergeInValue(Value *V, LatticeVal MergeWithV) {
+ void mergeInValue(Value *V, LatticeVal MergeWithV) {
assert(!V->getType()->isStructTy() &&
"non-structs should use markConstant");
- return mergeInValue(ValueState[V], V, MergeWithV);
+ mergeInValue(ValueState[V], V, MergeWithV);
}
/// getValueState - Return the LatticeVal object that corresponds to the
@@ -777,7 +783,7 @@
// If this PN returns a struct, just mark the result overdefined.
// TODO: We could do a lot better than this if code actually uses this.
if (PN.getType()->isStructTy())
- return (void)markOverdefined(&PN);
+ return markOverdefined(&PN);
if (getValueState(&PN).isOverdefined())
return; // Quick exit
@@ -785,7 +791,7 @@
// Super-extra-high-degree PHI nodes are unlikely to ever be marked constant,
// and slow us down a lot. Just mark them overdefined.
if (PN.getNumIncomingValues() > 64)
- return (void)markOverdefined(&PN);
+ return markOverdefined(&PN);
// Look at all of the executable operands of the PHI node. If any of them
// are overdefined, the PHI becomes overdefined as well. If they are all
@@ -801,7 +807,7 @@
continue;
if (IV.isOverdefined()) // PHI node becomes overdefined!
- return (void)markOverdefined(&PN);
+ return markOverdefined(&PN);
if (!OperandVal) { // Grab the first value.
OperandVal = IV.getConstant();
@@ -815,7 +821,7 @@
// Check to see if there are two different constants merging, if so, the PHI
// node is overdefined.
if (IV.getConstant() != OperandVal)
- return (void)markOverdefined(&PN);
+ return markOverdefined(&PN);
}
// If we exited the loop, this means that the PHI node only has constant
@@ -883,11 +889,11 @@
// If this returns a struct, mark all elements over defined, we don't track
// structs in structs.
if (EVI.getType()->isStructTy())
- return (void)markOverdefined(&EVI);
+ return markOverdefined(&EVI);
// If this is extracting from more than one level of struct, we don't know.
if (EVI.getNumIndices() != 1)
- return (void)markOverdefined(&EVI);
+ return markOverdefined(&EVI);
Value *AggVal = EVI.getAggregateOperand();
if (AggVal->getType()->isStructTy()) {
@@ -896,19 +902,19 @@
mergeInValue(getValueState(&EVI), &EVI, EltVal);
} else {
// Otherwise, must be extracting from an array.
- return (void)markOverdefined(&EVI);
+ return markOverdefined(&EVI);
}
}
void SCCPSolver::visitInsertValueInst(InsertValueInst &IVI) {
auto *STy = dyn_cast<StructType>(IVI.getType());
if (!STy)
- return (void)markOverdefined(&IVI);
+ return markOverdefined(&IVI);
// If this has more than one index, we can't handle it, drive all results to
// undef.
if (IVI.getNumIndices() != 1)
- return (void)markOverdefined(&IVI);
+ return markOverdefined(&IVI);
Value *Aggr = IVI.getAggregateOperand();
unsigned Idx = *IVI.idx_begin();
@@ -937,7 +943,7 @@
// If this select returns a struct, just mark the result overdefined.
// TODO: We could do a lot better than this if code actually uses this.
if (I.getType()->isStructTy())
- return (void)markOverdefined(&I);
+ return markOverdefined(&I);
LatticeVal CondValue = getValueState(I.getCondition());
if (CondValue.isUnknown())
@@ -958,12 +964,12 @@
// select ?, C, C -> C.
if (TVal.isConstant() && FVal.isConstant() &&
TVal.getConstant() == FVal.getConstant())
- return (void)markConstant(&I, FVal.getConstant());
+ return markConstant(&I, FVal.getConstant());
if (TVal.isUnknown()) // select ?, undef, X -> X.
- return (void)mergeInValue(&I, FVal);
+ return mergeInValue(&I, FVal);
if (FVal.isUnknown()) // select ?, X, undef -> X.
- return (void)mergeInValue(&I, TVal);
+ return mergeInValue(&I, TVal);
markOverdefined(&I);
}
@@ -981,7 +987,7 @@
// X op Y -> undef.
if (isa<UndefValue>(C))
return;
- return (void)markConstant(IV, &I, C);
+ return markConstant(IV, &I, C);
}
// If something is undef, wait for it to resolve.
@@ -994,7 +1000,7 @@
// overdefined, and we can replace it with zero.
if (I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction::SDiv)
if (V1State.isConstant() && V1State.getConstant()->isNullValue())
- return (void)markConstant(IV, &I, V1State.getConstant());
+ return markConstant(IV, &I, V1State.getConstant());
// If this is:
// -> AND/MUL with 0
@@ -1017,12 +1023,12 @@
// X and 0 = 0
// X * 0 = 0
if (NonOverdefVal->getConstant()->isNullValue())
- return (void)markConstant(IV, &I, NonOverdefVal->getConstant());
+ return markConstant(IV, &I, NonOverdefVal->getConstant());
} else {
// X or -1 = -1
if (ConstantInt *CI = NonOverdefVal->getConstantInt())
if (CI->isMinusOne())
- return (void)markConstant(IV, &I, NonOverdefVal->getConstant());
+ return markConstant(IV, &I, NonOverdefVal->getConstant());
}
}
}
@@ -1032,36 +1038,22 @@
// Handle ICmpInst instruction.
void SCCPSolver::visitCmpInst(CmpInst &I) {
+ LatticeVal V1State = getValueState(I.getOperand(0));
+ LatticeVal V2State = getValueState(I.getOperand(1));
+
LatticeVal &IV = ValueState[&I];
if (IV.isOverdefined()) return;
- Value *Op1 = I.getOperand(0);
- Value *Op2 = I.getOperand(1);
-
- // For parameters, use ParamState which includes constant range info if
- // available.
- auto V1Param = ParamState.find(Op1);
- ValueLatticeElement V1State = (V1Param != ParamState.end())
- ? V1Param->second
- : getValueState(Op1).toValueLattice();
-
- auto V2Param = ParamState.find(Op2);
- ValueLatticeElement V2State = V2Param != ParamState.end()
- ? V2Param->second
- : getValueState(Op2).toValueLattice();
-
- Constant *C = V1State.getCompare(I.getPredicate(), I.getType(), V2State);
- if (C) {
+ if (V1State.isConstant() && V2State.isConstant()) {
+ Constant *C = ConstantExpr::getCompare(
+ I.getPredicate(), V1State.getConstant(), V2State.getConstant());
if (isa<UndefValue>(C))
return;
- LatticeVal CV;
- CV.markConstant(C);
- mergeInValue(&I, CV);
- return;
+ return markConstant(IV, &I, C);
}
// If operands are still unknown, wait for it to resolve.
- if (!V1State.isOverdefined() && !V2State.isOverdefined() && !IV.isConstant())
+ if (!V1State.isOverdefined() && !V2State.isOverdefined())
return;
markOverdefined(&I);
@@ -1081,7 +1073,7 @@
return; // Operands are not resolved yet.
if (State.isOverdefined())
- return (void)markOverdefined(&I);
+ return markOverdefined(&I);
assert(State.isConstant() && "Unknown state!");
Operands.push_back(State.getConstant());
@@ -1119,7 +1111,7 @@
void SCCPSolver::visitLoadInst(LoadInst &I) {
// If this load is of a struct, just mark the result overdefined.
if (I.getType()->isStructTy())
- return (void)markOverdefined(&I);
+ return markOverdefined(&I);
LatticeVal PtrVal = getValueState(I.getOperand(0));
if (PtrVal.isUnknown()) return; // The pointer is not resolved yet!
@@ -1128,7 +1120,7 @@
if (IV.isOverdefined()) return;
if (!PtrVal.isConstant() || I.isVolatile())
- return (void)markOverdefined(IV, &I);
+ return markOverdefined(IV, &I);
Constant *Ptr = PtrVal.getConstant();
@@ -1157,7 +1149,7 @@
if (Constant *C = ConstantFoldLoadFromConstPtr(Ptr, I.getType(), DL)) {
if (isa<UndefValue>(C))
return;
- return (void)markConstant(IV, &I, C);
+ return markConstant(IV, &I, C);
}
// Otherwise we cannot say for certain what value this load will produce.
@@ -1189,7 +1181,7 @@
if (State.isUnknown())
return; // Operands are not resolved yet.
if (State.isOverdefined())
- return (void)markOverdefined(I);
+ return markOverdefined(I);
assert(State.isConstant() && "Unknown state!");
Operands.push_back(State.getConstant());
}
@@ -1203,12 +1195,12 @@
// call -> undef.
if (isa<UndefValue>(C))
return;
- return (void)markConstant(I, C);
+ return markConstant(I, C);
}
}
// Otherwise, we don't know anything about this call, mark it overdefined.
- return (void)markOverdefined(I);
+ return markOverdefined(I);
}
// If this is a local function that doesn't have its address taken, mark its
@@ -1236,16 +1228,8 @@
} else {
// Most other parts of the Solver still only use the simpler value
// lattice, so we propagate changes for parameters to both lattices.
- LatticeVal ConcreteArgument = getValueState(*CAI);
- bool ParamChanged =
- getParamState(&*AI).mergeIn(ConcreteArgument.toValueLattice(), DL);
- bool ValueChanged = mergeInValue(&*AI, ConcreteArgument);
- // Add argument to work list, if the state of a parameter changes but
- // ValueState does not change (because it is already overdefined there),
- // We have to take changes in ParamState into account, as it is used
- // when evaluating Cmp instructions.
- if (!ValueChanged && ParamChanged)
- pushToWorkList(ValueState[&*AI], &*AI);
+ getParamState(&*AI).mergeIn(getValueState(*CAI).toValueLattice(), DL);
+ mergeInValue(&*AI, getValueState(*CAI));
}
}
}
@@ -1538,11 +1522,7 @@
break;
case Instruction::ICmp:
// X == undef -> undef. Other comparisons get more complicated.
- Op0LV = getValueState(I.getOperand(0));
- Op1LV = getValueState(I.getOperand(1));
-
- if ((Op0LV.isUnknown() || Op1LV.isUnknown()) &&
- cast<ICmpInst>(&I)->isEquality())
+ if (cast<ICmpInst>(&I)->isEquality())
break;
markOverdefined(&I);
return true;
@@ -1639,6 +1619,45 @@
return false;
}
+static bool tryToReplaceWithConstantRange(SCCPSolver &Solver, Value *V) {
+ bool Changed = false;
+
+ // Currently we only use range information for integer values.
+ if (!V->getType()->isIntegerTy())
+ return false;
+
+ const ValueLatticeElement &IV = Solver.getLatticeValueFor(V);
+ if (!IV.isConstantRange())
+ return false;
+
+ for (auto UI = V->uses().begin(), E = V->uses().end(); UI != E;) {
+ const Use &U = *UI++;
+ auto *Icmp = dyn_cast<ICmpInst>(U.getUser());
+ if (!Icmp || !Solver.isBlockExecutable(Icmp->getParent()))
+ continue;
+
+ auto getIcmpLatticeValue = [&](Value *Op) {
+ if (auto *C = dyn_cast<Constant>(Op))
+ return ValueLatticeElement::get(C);
+ return Solver.getLatticeValueFor(Op);
+ };
+
+ ValueLatticeElement A = getIcmpLatticeValue(Icmp->getOperand(0));
+ ValueLatticeElement B = getIcmpLatticeValue(Icmp->getOperand(1));
+
+ Constant *C = A.getCompare(Icmp->getPredicate(), Icmp->getType(), B);
+ if (C) {
+ Icmp->replaceAllUsesWith(C);
+ LLVM_DEBUG(dbgs() << "Replacing " << *Icmp << " with " << *C
+ << ", because of range information " << A << " " << B
+ << "\n");
+ Icmp->eraseFromParent();
+ Changed = true;
+ }
+ }
+ return Changed;
+}
+
static bool tryToReplaceWithConstant(SCCPSolver &Solver, Value *V) {
Constant *Const = nullptr;
if (V->getType()->isStructTy()) {
@@ -1656,11 +1675,19 @@
}
Const = ConstantStruct::get(ST, ConstVals);
} else {
- const LatticeVal &IV = Solver.getLatticeValueFor(V);
+ const ValueLatticeElement &IV = Solver.getLatticeValueFor(V);
if (IV.isOverdefined())
return false;
- Const = IV.isConstant() ? IV.getConstant() : UndefValue::get(V->getType());
+ if (IV.isConstantRange()) {
+ if (IV.getConstantRange().isSingleElement())
+ Const =
+ ConstantInt::get(V->getType(), IV.asConstantInteger().getValue());
+ else
+ return false;
+ } else
+ Const =
+ IV.isConstant() ? IV.getConstant() : UndefValue::get(V->getType());
}
assert(Const && "Constant is nullptr here!");
@@ -1901,6 +1928,9 @@
++IPNumArgsElimed;
continue;
}
+
+ if (!AI->use_empty() && tryToReplaceWithConstantRange(Solver, &*AI))
+ ++IPNumRangeInfoUsed;
}
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
diff --git a/test/Transforms/SCCP/ip-constant-ranges.ll b/test/Transforms/SCCP/ip-constant-ranges.ll
index 704ea97..22a239d 100644
--- a/test/Transforms/SCCP/ip-constant-ranges.ll
+++ b/test/Transforms/SCCP/ip-constant-ranges.ll
@@ -2,7 +2,11 @@
; Constant range for %a is [1, 48) and for %b is [301, 1000)
; CHECK-LABEL: f1
-; CHECK: ret i32 undef
+; CHECK-NOT: icmp
+; CHECK: %a.1 = select i1 false, i32 1, i32 2
+; CHECK: %b.1 = select i1 true, i32 1, i32 2
+; CHECK: %a.2 = select i1 false, i32 1, i32 2
+; CHECK: %b.2 = select i1 true, i32 1, i32 2
define internal i32 @f1(i32 %a, i32 %b) {
entry:
%cmp.a = icmp sgt i32 %a, 300
@@ -24,11 +28,10 @@
; CHECK-LABEL: f2
; CHECK: %cmp = icmp sgt i32 %x, 300
; CHECK: %res1 = select i1 %cmp, i32 1, i32 2
+; CHECK-NEXT: %res2 = select i1 true, i32 3, i32 4
+; CHECK-NEXT: %res3 = select i1 true, i32 5, i32 6
; CHECK-NEXT: %res4 = select i1 %cmp4, i32 3, i32 4
-; CHECK-NEXT: %res6 = add i32 %res1, 3
-; CHECK-NEXT: %res7 = add i32 5, %res4
-; CHECK-NEXT: %res = add i32 %res6, 5
-; CHECK-NEXT: ret i32 %res
+; CHECK-NEXT: %res5 = select i1 true, i32 5, i32 6
define internal i32 @f2(i32 %x) {
entry:
%cmp = icmp sgt i32 %x, 300
@@ -54,7 +57,8 @@
%call2 = tail call i32 @f1(i32 47, i32 999)
%call3 = tail call i32 @f2(i32 47)
%call4 = tail call i32 @f2(i32 301)
- %res.1 = add nsw i32 12, %call3
+ %res = add nsw i32 %call1, %call2
+ %res.1 = add nsw i32 %res, %call3
%res.2 = add nsw i32 %res.1, %call4
ret i32 %res.2
}
@@ -141,9 +145,9 @@
; Constant range for %x is [47, 302)
; CHECK-LABEL: @f5
; CHECK-NEXT: entry:
-; CHECK-NEXT: %cmp = icmp sgt i32 %x, undef
-; CHECK-NEXT: %res1 = select i1 %cmp, i32 1, i32 2
-; CHECK-NEXT: %res = add i32 %res1, 3
+; CHECK-NEXT: %res1 = select i1 undef, i32 1, i32 2
+; CHECK-NEXT: %res2 = select i1 undef, i32 3, i32 4
+; CHECK-NEXT: %res = add i32 %res1, %res2
; CHECK-NEXT: ret i32 %res
define internal i32 @f5(i32 %x) {
entry:
@@ -163,36 +167,3 @@
%res = add nsw i32 %call1, %call2
ret i32 %res
}
-
-; Make sure we do re-evaluate the function after ParamState changes.
-; CHECK-LABEL: @recursive_f
-; CHECK-LABEL: entry:
-; CHECK: %cmp = icmp eq i32 %i, 0
-; CHECK-NEXT: br i1 %cmp, label %if.then, label %if.else
-define internal i32 @recursive_f(i32 %i) {
-entry:
- %cmp = icmp eq i32 %i, 0
- br i1 %cmp, label %if.then, label %if.else
-
-if.then: ; preds = %entry
- br label %return
-
-if.else: ; preds = %entry
- %sub = sub nsw i32 %i, 1
- %call = call i32 @recursive_f(i32 %sub)
- %add = add i32 %i, %call
- br label %return
-
-return: ; preds = %if.else, %if.then
- %retval.0 = phi i32 [ 0, %if.then ], [ %add, %if.else ]
- ret i32 %retval.0
-}
-
-; CHECK-LABEL: @caller5
-; CHECK: %call = call i32 @recursive_f(i32 42)
-; CHECK-NEXT: ret i32 %call
-define i32 @caller5() {
-entry:
- %call = call i32 @recursive_f(i32 42)
- ret i32 %call
-}
