Allow the construction of SCEVs with SCEVCouldNotCompute operands, by
implementing folding. Fixes PR2857.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57049 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 5125804..473057c 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -676,6 +676,9 @@
return getAddRecExpr(Operands, AddRec->getLoop());
}
+ if (isa<SCEVCouldNotCompute>(Op))
+ return new SCEVCouldNotCompute();
+
SCEVTruncateExpr *&Result = (*SCEVTruncates)[std::make_pair(Op, Ty)];
if (Result == 0) Result = new SCEVTruncateExpr(Op, Ty);
return Result;
@@ -691,6 +694,9 @@
// operands (often constants). This would allow analysis of something like
// this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
+ if (isa<SCEVCouldNotCompute>(Op))
+ return new SCEVCouldNotCompute();
+
SCEVZeroExtendExpr *&Result = (*SCEVZeroExtends)[std::make_pair(Op, Ty)];
if (Result == 0) Result = new SCEVZeroExtendExpr(Op, Ty);
return Result;
@@ -706,6 +712,9 @@
// operands (often constants). This would allow analysis of something like
// this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
+ if (isa<SCEVCouldNotCompute>(Op))
+ return new SCEVCouldNotCompute();
+
SCEVSignExtendExpr *&Result = (*SCEVSignExtends)[std::make_pair(Op, Ty)];
if (Result == 0) Result = new SCEVSignExtendExpr(Op, Ty);
return Result;
@@ -734,6 +743,10 @@
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops);
+ // Could not compute plus anything equals could not compute.
+ if (isa<SCEVCouldNotCompute>(Ops.back()))
+ return new SCEVCouldNotCompute();
+
// If there are any constants, fold them together.
unsigned Idx = 0;
if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
@@ -959,6 +972,21 @@
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops);
+ if (isa<SCEVCouldNotCompute>(Ops.back())) {
+ // CNC * 0 = 0
+ for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {
+ if (Ops[i]->getSCEVType() != scConstant)
+ break;
+
+ SCEVConstant *SC = cast<SCEVConstant>(Ops[i]);
+ if (SC->getValue()->isMinValue(false))
+ return SC;
+ }
+
+ // Otherwise, we can't compute it.
+ return new SCEVCouldNotCompute();
+ }
+
// If there are any constants, fold them together.
unsigned Idx = 0;
if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
@@ -1124,6 +1152,9 @@
// FIXME: implement folding of (X*4)/4 when we know X*4 doesn't overflow.
+ if (isa<SCEVCouldNotCompute>(LHS) || isa<SCEVCouldNotCompute>(RHS))
+ return new SCEVCouldNotCompute();
+
SCEVUDivExpr *&Result = (*SCEVUDivs)[std::make_pair(LHS, RHS)];
if (Result == 0) Result = new SCEVUDivExpr(LHS, RHS);
return Result;
@@ -1171,6 +1202,12 @@
}
}
+ // Refuse to build an AddRec out of SCEVCouldNotCompute.
+ for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
+ if (isa<SCEVCouldNotCompute>(Operands[i]))
+ return new SCEVCouldNotCompute();
+ }
+
SCEVAddRecExpr *&Result =
(*SCEVAddRecExprs)[std::make_pair(L, std::vector<SCEV*>(Operands.begin(),
Operands.end()))];
@@ -1193,6 +1230,21 @@
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops);
+ if (isa<SCEVCouldNotCompute>(Ops.back())) {
+ // CNC smax +inf = +inf.
+ for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {
+ if (Ops[i]->getSCEVType() != scConstant)
+ break;
+
+ SCEVConstant *SC = cast<SCEVConstant>(Ops[i]);
+ if (SC->getValue()->isMaxValue(true))
+ return SC;
+ }
+
+ // Otherwise, we can't compute it.
+ return new SCEVCouldNotCompute();
+ }
+
// If there are any constants, fold them together.
unsigned Idx = 0;
if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
@@ -1273,6 +1325,21 @@
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops);
+ if (isa<SCEVCouldNotCompute>(Ops[0])) {
+ // CNC umax inf = inf.
+ for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {
+ if (Ops[i]->getSCEVType() != scConstant)
+ break;
+
+ SCEVConstant *SC = cast<SCEVConstant>(Ops[i]);
+ if (SC->getValue()->isMaxValue(false))
+ return SC;
+ }
+
+ // Otherwise, we can't compute it.
+ return new SCEVCouldNotCompute();
+ }
+
// If there are any constants, fold them together.
unsigned Idx = 0;
if (SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {