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[StackSafety,NFC] Remove SCEVRewriteVisitor 

Summary: Depends on D80956.

Reviewers: eugenis

Reviewed By: eugenis

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80976
This commit is contained in:
Vitaly Buka 2020-06-01 21:40:47 -07:00
parent 590964c835
commit 81826c7ac6
1 changed files with 7 additions and 23 deletions
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30
llvm/lib/Analysis/StackSafetyAnalysis.cpp
View File

@ -42,25 +42,6 @@ static cl::opt<int> StackSafetyPrint("stack-safety-print", cl::init(0),
namespace {
/// Rewrite an SCEV expression for a memory access address to an expression that
/// represents offset from the given alloca.
class AllocaOffsetRewriter : public SCEVRewriteVisitor<AllocaOffsetRewriter> {
const Value *AllocaPtr;
public:
AllocaOffsetRewriter(ScalarEvolution &SE, const Value *AllocaPtr)
: SCEVRewriteVisitor(SE), AllocaPtr(AllocaPtr) {}
const SCEV *visitUnknown(const SCEVUnknown *Expr) {
// FIXME: look through one or several levels of definitions?
// This can be inttoptr(AllocaPtr) and SCEV would not unwrap
// it for us.
if (Expr->getValue() == AllocaPtr)
return SE.getZero(Expr->getType());
return Expr;
}
};
/// Describes use of address in as a function call argument.
template <typename CalleeTy> struct CallInfo {
/// Function being called.
@ -226,12 +207,15 @@ public:
};
ConstantRange StackSafetyLocalAnalysis::offsetFrom(Value *Addr, Value *Base) {
if (!SE.isSCEVable(Addr->getType()))
if (!SE.isSCEVable(Addr->getType()) || !SE.isSCEVable(Base->getType()))
return UnknownRange;
AllocaOffsetRewriter Rewriter(SE, Base);
const SCEV *Expr = Rewriter.visit(SE.getSCEV(Addr));
ConstantRange Offset = SE.getSignedRange(Expr);
auto *PtrTy = IntegerType::getInt8PtrTy(SE.getContext());
const SCEV *AddrExp = SE.getTruncateOrZeroExtend(SE.getSCEV(Addr), PtrTy);
const SCEV *BaseExp = SE.getTruncateOrZeroExtend(SE.getSCEV(Base), PtrTy);
const SCEV *Diff = SE.getMinusSCEV(AddrExp, BaseExp);
ConstantRange Offset = SE.getSignedRange(Diff);
if (isUnsafe(Offset))
return UnknownRange;
return Offset.sextOrTrunc(PointerSize);