diff options
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolution.cpp | 11 | ||||
| -rw-r--r-- | llvm/test/Analysis/ScalarEvolution/max-addrec-size.ll | 33 |
2 files changed, 44 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index b973203a89b..b726fd97b70 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -162,6 +162,11 @@ static cl::opt<unsigned> cl::desc("Maximum depth of recursive SExt/ZExt"), cl::init(8)); +static cl::opt<unsigned> + MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden, + cl::desc("Max coefficients in AddRec during evolving"), + cl::init(16)); + //===----------------------------------------------------------------------===// // SCEV class definitions //===----------------------------------------------------------------------===// @@ -2878,6 +2883,12 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop) continue; + // Limit max number of arguments to avoid creation of unreasonably big + // SCEVAddRecs with very complex operands. + if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 > + MaxAddRecSize) + continue; + bool Overflow = false; Type *Ty = AddRec->getType(); bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64; diff --git a/llvm/test/Analysis/ScalarEvolution/max-addrec-size.ll b/llvm/test/Analysis/ScalarEvolution/max-addrec-size.ll new file mode 100644 index 00000000000..aad0ddda37b --- /dev/null +++ b/llvm/test/Analysis/ScalarEvolution/max-addrec-size.ll @@ -0,0 +1,33 @@ +; RUN: opt -analyze -scalar-evolution -scalar-evolution-max-add-rec-size=3 < %s | FileCheck %s + +; Show that we are able to avoid creation of huge SCEVs by capping the max +; AddRec size. +define i32 @test_01(i32 %a, i32 %b) { + +; CHECK-LABEL: Classifying expressions for: @test_01 +; CHECK-NEXT: %iv = phi i32 [ %a, %entry ], [ %iv.next, %loop ] +; CHECK-NEXT: --> {%a,+,%b}<%loop> U: full-set S: full-set +; CHECK-NEXT: %iv.next = add i32 %iv, %b +; CHECK-NEXT: --> {(%a + %b),+,%b}<%loop> U: full-set S: full-set +; CHECK-NEXT: %x1 = mul i32 %iv, %iv.next +; CHECK-NEXT: --> {((%a + %b) * %a),+,(((2 * %a) + (2 * %b)) * %b),+,(2 * %b * %b)}<%loop> U: full-set S: full-set +; CHECK-NEXT: %x2 = mul i32 %x1, %x1 +; CHECK-NEXT: --> ({((%a + %b) * %a),+,(((2 * %a) + (2 * %b)) * %b),+,(2 * %b * %b)}<%loop> * {((%a + %b) * %a),+,(((2 * %a) + (2 * %b)) * %b),+,(2 * %b * %b)}<%loop>) U: full-set S: full-set +; CHECK-NEXT: %x3 = mul i32 %x2, %x1 +; CHECK-NEXT: --> ({((%a + %b) * %a),+,(((2 * %a) + (2 * %b)) * %b),+,(2 * %b * %b)}<%loop> * {((%a + %b) * %a),+,(((2 * %a) + (2 * %b)) * %b),+,(2 * %b * %b)}<%loop> * {((%a + %b) * %a),+,(((2 * %a) + (2 * %b)) * %b),+,(2 * %b * %b)}<%loop>) U: full-set S: full-set + +entry: + br label %loop + +loop: + %iv = phi i32 [ %a, %entry ], [ %iv.next, %loop ] + %iv.next = add i32 %iv, %b + %cond = icmp slt i32 %iv.next, 1000 + br i1 %cond, label %loop, label %exit + +exit: + %x1 = mul i32 %iv, %iv.next + %x2 = mul i32 %x1, %x1 + %x3 = mul i32 %x2, %x1 + ret i32 %x3 +} |
