Index: lib/Analysis/ScalarEvolution.cpp =================================================================== --- lib/Analysis/ScalarEvolution.cpp +++ lib/Analysis/ScalarEvolution.cpp @@ -59,6 +59,7 @@ //===----------------------------------------------------------------------===// #include "llvm/Analysis/ScalarEvolution.h" +#include "llvm/ADT/Optional.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/Statistic.h" @@ -79,6 +80,7 @@ #include "llvm/IR/InstIterator.h" #include "llvm/IR/Instructions.h" #include "llvm/IR/LLVMContext.h" +#include "llvm/IR/Metadata.h" #include "llvm/IR/Operator.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" @@ -3400,6 +3402,31 @@ return 0; } +/// GetRangeFromMetadata - Helper method to assign a range to V from +/// metadata present in the IR. +static Optional GetRangeFromMetadata(Value *V) { + if (Instruction *I = dyn_cast(V)) { + if (MDNode *MD = I->getMetadata(LLVMContext::MD_range)) { + ConstantRange TotalRange( + cast(I->getType())->getBitWidth(), false); + + unsigned NumRanges = MD->getNumOperands() / 2; + assert(NumRanges >= 1); + + for (unsigned i = 0; i < NumRanges; ++i) { + ConstantInt *Lower = cast(MD->getOperand(2*i + 0)); + ConstantInt *Upper = cast(MD->getOperand(2*i + 1)); + ConstantRange Range(Lower->getValue(), Upper->getValue()); + TotalRange = TotalRange.unionWith(Range); + } + + return TotalRange; + } + } + + return None; +} + /// getUnsignedRange - Determine the unsigned range for a particular SCEV. /// ConstantRange @@ -3529,6 +3556,12 @@ } if (const SCEVUnknown *U = dyn_cast(S)) { + // Check if the IR explicitly contains !range metadata. + Optional MDRange = GetRangeFromMetadata(U->getValue()); + if (MDRange.hasValue()) { + return setUnsignedRange(S, MDRange.getValue()); + } + // For a SCEVUnknown, ask ValueTracking. APInt Zeros(BitWidth, 0), Ones(BitWidth, 0); computeKnownBits(U->getValue(), Zeros, Ones, DL, 0, AT, nullptr, DT); @@ -3680,6 +3713,12 @@ } if (const SCEVUnknown *U = dyn_cast(S)) { + // Check if the IR explicitly contains !range metadata. + Optional MDRange = GetRangeFromMetadata(U->getValue()); + if (MDRange.hasValue()) { + return setSignedRange(S, MDRange.getValue()); + } + // For a SCEVUnknown, ask ValueTracking. if (!U->getValue()->getType()->isIntegerTy() && !DL) return setSignedRange(U, ConservativeResult); @@ -6307,6 +6346,8 @@ // (interprocedural conditions notwithstanding). if (!L) return true; + if (isKnownPredicateWithRanges(Pred, LHS, RHS)) return true; + BasicBlock *Latch = L->getLoopLatch(); if (!Latch) return false; @@ -6342,6 +6383,8 @@ // (interprocedural conditions notwithstanding). if (!L) return false; + if (isKnownPredicateWithRanges(Pred, LHS, RHS)) return true; + // Starting at the loop predecessor, climb up the predecessor chain, as long // as there are predecessors that can be found that have unique successors // leading to the original header. Index: test/Transforms/IndVarSimplify/use-range-metadata.ll =================================================================== --- /dev/null +++ test/Transforms/IndVarSimplify/use-range-metadata.ll @@ -0,0 +1,37 @@ +;; RUN: opt -S < %s -indvars | FileCheck %s + +;; Check if IndVarSimplify understands !range metadata. + +declare void @abort() + +define i1 @iterate(i32* nocapture readonly %buffer) { +entry: + %length = load i32* %buffer, !range !0 + br label %loop.preheader + +loop.preheader: + br label %loop + +loop: + %idx = phi i32 [ %idx.inc, %loop.next ], [ 0, %loop.preheader ] + %oob.pred = icmp slt i32 %idx, %length + br i1 %oob.pred, label %loop.next, label %oob +; CHECK: br i1 true, label %loop.next, label %oob + +loop.next: + %idx.inc = add i32 %idx, 1 + %exit.pred = icmp slt i32 %idx.inc, %length + br i1 %exit.pred, label %loop, label %abort.loopexit + +abort.loopexit: + br label %abort + +abort: + ret i1 false + +oob: + tail call void @abort() + ret i1 false +} + +!0 = metadata !{i32 1, i32 100}