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Revert r296366 "[InlineFunction] add nonnull assumptions based on argument attributes" 

It causes miscompiles e.g. during self-host of Clang (PR32082).

llvm-svn: 296398
This commit is contained in:
Hans Wennborg 2017-02-27 22:33:02 +00:00
parent c78a5560fe
commit 2d5841fa73
2 changed files with 23 additions and 41 deletions
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58
llvm/lib/Transforms/Utils/InlineFunction.cpp
View File

@ -1093,52 +1093,38 @@ static void AddAliasScopeMetadata(CallSite CS, ValueToValueMapTy &VMap,
}
}
/// Add @llvm.assume-based assumptions to preserve information supplied by
/// argument attributes because the attributes will disappear after inlining.
static void addAssumptions(CallSite CS, InlineFunctionInfo &IFI) {
if (!IFI.GetAssumptionCache)
/// If the inlined function has non-byval align arguments, then
/// add @llvm.assume-based alignment assumptions to preserve this information.
static void AddAlignmentAssumptions(CallSite CS, InlineFunctionInfo &IFI) {
if (!PreserveAlignmentAssumptions || !IFI.GetAssumptionCache)
return;
AssumptionCache *AC = &(*IFI.GetAssumptionCache)(*CS.getCaller());
auto &DL = CS.getCaller()->getParent()->getDataLayout();
// To avoid inserting redundant assumptions, check that an assumption provides
// new information in the caller. This might require a dominator tree.
// To avoid inserting redundant assumptions, we should check for assumptions
// already in the caller. To do this, we might need a DT of the caller.
DominatorTree DT;
bool DTCalculated = false;
auto calcDomTreeIfNeeded = [&]() {
if (!DTCalculated) {
DT.recalculate(*CS.getCaller());
DTCalculated = true;
}
};
Function *CalledFunc = CS.getCalledFunction();
IRBuilder<> Builder(CS.getInstruction());
for (Argument &Arg : CalledFunc->args()) {
Value *ArgVal = CS.getArgument(Arg.getArgNo());
unsigned Align = Arg.getType()->isPointerTy() ? Arg.getParamAlignment() : 0;
if (PreserveAlignmentAssumptions && Align &&
!Arg.hasByValOrInAllocaAttr() && !Arg.hasNUses(0)) {
if (Align && !Arg.hasByValOrInAllocaAttr() && !Arg.hasNUses(0)) {
if (!DTCalculated) {
DT.recalculate(*CS.getCaller());
DTCalculated = true;
}
// If we can already prove the asserted alignment in the context of the
// caller, then don't bother inserting the assumption.
calcDomTreeIfNeeded();
if (getKnownAlignment(ArgVal, DL, CS.getInstruction(), AC, &DT) < Align) {
CallInst *Asmp = Builder.CreateAlignmentAssumption(DL, ArgVal, Align);
AC->registerAssumption(Asmp);
}
}
Value *ArgVal = CS.getArgument(Arg.getArgNo());
if (getKnownAlignment(ArgVal, DL, CS.getInstruction(), AC, &DT) >= Align)
continue;
if (Arg.hasNonNullAttr()) {
// If we can already prove nonnull in the context of the caller, then
// don't bother inserting the assumption.
calcDomTreeIfNeeded();
if (!isKnownNonNullAt(ArgVal, CS.getInstruction(), &DT)) {
Value *NotNull = Builder.CreateIsNotNull(ArgVal);
CallInst *Asmp = Builder.CreateAssumption(NotNull);
AC->registerAssumption(Asmp);
}
CallInst *NewAsmp = IRBuilder<>(CS.getInstruction())
.CreateAlignmentAssumption(DL, ArgVal, Align);
AC->registerAssumption(NewAsmp);
}
}
}
@ -1635,10 +1621,10 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
VMap[&*I] = ActualArg;
}
// Add assumptions if necessary. We do this before the inlined instructions
// are actually cloned into the caller so that we can easily check what will
// be known at the start of the inlined code.
addAssumptions(CS, IFI);
// Add alignment assumptions if necessary. We do this before the inlined
// instructions are actually cloned into the caller so that we can easily
// check what will be known at the start of the inlined code.
AddAlignmentAssumptions(CS, IFI);
// We want the inliner to prune the code as it copies. We would LOVE to
// have no dead or constant instructions leftover after inlining occurs

6
llvm/test/Transforms/Inline/arg-attr-propagation.ll
View File

@ -12,13 +12,11 @@ define i32 @callee(i32* dereferenceable(32) %t1) {
ret i32 %t2
}
; Add a nonnull assumption.
; FIXME: All dereferenceability information is lost.
; The caller argument could be known nonnull and dereferenceable(32).
define i32 @caller1(i32* %t1) {
; CHECK-LABEL: @caller1(i32* %t1)
; CHECK-NEXT: [[TMP1:%.*]] = icmp ne i32* %t1, null
; CHECK-NEXT: call void @llvm.assume(i1 [[TMP1]])
; CHECK-NEXT: [[T2_I:%.*]] = load i32, i32* %t1
; CHECK-NEXT: ret i32 [[T2_I]]
;
@ -26,7 +24,6 @@ define i32 @caller1(i32* %t1) {
ret i32 %t2
}
; Don't add a nonnull assumption if it's redundant.
; The caller argument is nonnull, but that can be explicit.
; The dereferenceable amount could be increased.
@ -39,7 +36,6 @@ define i32 @caller2(i32* dereferenceable(31) %t1) {
ret i32 %t2
}
; Don't add a nonnull assumption if it's redundant.
; The caller argument is nonnull, but that can be explicit.
; Make sure that we don't propagate a smaller dereferenceable amount.