diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -2119,8 +2119,9 @@
"<tag>"([ <holds for value> [, <attribute argument>] ])
-* The tag of the operand bundle is the name of attribute that can be assumed
- to hold.
+* The tag of the operand bundle is usually the name of attribute that can be
+ assumed to hold. It can also be `ignore`, this tag doesn't contain any
+ information and should be ignored.
* The first argument if present is the value for which the attribute hold.
* The second argument if present is an argument of the attribute.
diff --git a/llvm/include/llvm/IR/User.h b/llvm/include/llvm/IR/User.h
--- a/llvm/include/llvm/IR/User.h
+++ b/llvm/include/llvm/IR/User.h
@@ -218,6 +218,11 @@
NumUserOperands = NumOps;
}
+ /// A droppable user is a user for which uses can be dropped without affecting
+ /// correctness and should be dropped rather than preventing a transformation
+ /// from happening.
+ bool isDroppable() const;
+
// ---------------------------------------------------------------------------
// Operand Iterator interface...
//
diff --git a/llvm/include/llvm/IR/Value.h b/llvm/include/llvm/IR/Value.h
--- a/llvm/include/llvm/IR/Value.h
+++ b/llvm/include/llvm/IR/Value.h
@@ -444,6 +444,34 @@
/// This is logically equivalent to getNumUses() >= N.
bool hasNUsesOrMore(unsigned N) const;
+ /// Return true if there is exactly one user of this value that cannot be
+ /// dropped.
+ ///
+ /// This is specialized because it is a common request and does not require
+ /// traversing the whole use list.
+ Use *getSingleUndroppableUse();
+
+ /// Return true if there this value.
+ ///
+ /// This is specialized because it is a common request and does not require
+ /// traversing the whole use list.
+ bool hasNUndroppableUses(unsigned N) const;
+
+ /// Return true if this value has N users or more.
+ ///
+ /// This is logically equivalent to getNumUses() >= N.
+ bool hasNUndroppableUsesOrMore(unsigned N) const;
+
+ /// Remove every uses that can safely be removed.
+ ///
+ /// This will remove for example uses in llvm.assume.
+ /// This should be used when performing want to perform a tranformation but
+ /// some Droppable uses pervent it.
+ /// This function optionally takes a filter to only remove some droppable
+ /// uses.
+ void dropDroppableUses(llvm::function_ref<bool(const Use *)> ShouldDrop =
+ [](const Use *) { return true; });
+
/// Check if this value is used in the specified basic block.
bool isUsedInBasicBlock(const BasicBlock *BB) const;
diff --git a/llvm/lib/IR/KnowledgeRetention.cpp b/llvm/lib/IR/KnowledgeRetention.cpp
--- a/llvm/lib/IR/KnowledgeRetention.cpp
+++ b/llvm/lib/IR/KnowledgeRetention.cpp
@@ -197,51 +197,27 @@
if (Assume.bundle_op_infos().empty())
return false;
- CallInst::bundle_op_iterator Lookup;
-
- /// The right attribute can be found by binary search. After this finding the
- /// right WasOn needs to be done via linear search.
- /// Element have been ordered by argument value so the first we find is the
- /// one we need.
- if (AQR == AssumeQuery::Lowest)
- Lookup =
- llvm::lower_bound(Assume.bundle_op_infos(), AttrName,
- [](const CallBase::BundleOpInfo &BOI, StringRef RHS) {
- return BOI.Tag->getKey() < RHS;
- });
- else
- Lookup = std::prev(
- llvm::upper_bound(Assume.bundle_op_infos(), AttrName,
- [](StringRef LHS, const CallBase::BundleOpInfo &BOI) {
- return LHS < BOI.Tag->getKey();
- }));
-
- if (Lookup == Assume.bundle_op_info_end() ||
- Lookup->Tag->getKey() != AttrName)
- return false;
- if (IsOn) {
- assert((Lookup->End - Lookup->Begin > BOIE_WasOn) &&
- "missing argument of attribute");
- while (true) {
- if (Lookup == Assume.bundle_op_info_end() ||
- Lookup->Tag->getKey() != AttrName)
- return false;
- if (getValueFromBundleOpInfo(Assume, *Lookup, BOIE_WasOn) == IsOn)
- break;
- if (AQR == AssumeQuery::Highest &&
- Lookup == Assume.bundle_op_info_begin())
- return false;
- Lookup = Lookup + (AQR == AssumeQuery::Lowest ? 1 : -1);
+ auto Loop = [&](auto &&Range) {
+ for (auto &BOI : Range) {
+ if (BOI.Tag->getKey() != AttrName)
+ continue;
+ if (IsOn && (BOI.End - BOI.Begin <= BOIE_WasOn ||
+ IsOn != getValueFromBundleOpInfo(Assume, BOI, BOIE_WasOn)))
+ continue;
+ if (ArgVal) {
+ assert(BOI.End - BOI.Begin > BOIE_Argument);
+ *ArgVal = cast<ConstantInt>(
+ getValueFromBundleOpInfo(Assume, BOI, BOIE_Argument))
+ ->getZExtValue();
+ }
+ return true;
}
- }
+ return false;
+ };
- if (Lookup->End - Lookup->Begin < BOIE_Argument)
- return true;
- if (ArgVal)
- *ArgVal = cast<ConstantInt>(
- getValueFromBundleOpInfo(Assume, *Lookup, BOIE_Argument))
- ->getZExtValue();
- return true;
+ if (AQR == AssumeQuery::Lowest)
+ return Loop(Assume.bundle_op_infos());
+ return Loop(reverse(Assume.bundle_op_infos()));
}
void llvm::fillMapFromAssume(CallInst &AssumeCI, RetainedKnowledgeMap &Result) {
diff --git a/llvm/lib/IR/User.cpp b/llvm/lib/IR/User.cpp
--- a/llvm/lib/IR/User.cpp
+++ b/llvm/lib/IR/User.cpp
@@ -9,6 +9,7 @@
#include "llvm/IR/User.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/GlobalValue.h"
+#include "llvm/IR/IntrinsicInst.h"
namespace llvm {
class BasicBlock;
@@ -105,6 +106,12 @@
reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes, DI->SizeInBytes);
}
+bool User::isDroppable() const {
+ if (const auto *Intr = dyn_cast<IntrinsicInst>(this))
+ return Intr->getIntrinsicID() == Intrinsic::assume;
+ return false;
+}
+
//===----------------------------------------------------------------------===//
// User operator new Implementations
//===----------------------------------------------------------------------===//
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -141,6 +141,51 @@
return hasNItemsOrMore(use_begin(), use_end(), N);
}
+static bool isUnDroppableUser(const User *U) { return !U->isDroppable(); }
+
+Use *Value::getSingleUndroppableUse() {
+ Use *Result = nullptr;
+ for (Use &U : uses()) {
+ if (!U.getUser()->isDroppable()) {
+ if (Result)
+ return nullptr;
+ Result = &U;
+ }
+ }
+ return Result;
+}
+
+bool Value::hasNUndroppableUses(unsigned int N) const {
+ return hasNItems(user_begin(), user_end(), N, isUnDroppableUser);
+}
+
+bool Value::hasNUndroppableUsesOrMore(unsigned int N) const {
+ return hasNItemsOrMore(user_begin(), user_end(), N, isUnDroppableUser);
+}
+
+void Value::dropDroppableUses(
+ llvm::function_ref<bool(const Use *)> ShouldDrop) {
+ SmallVector<Use *, 8> ToBeEdited;
+ for (Use &U : uses())
+ if (U.getUser()->isDroppable() && ShouldDrop(&U))
+ ToBeEdited.push_back(&U);
+ for (Use *U : ToBeEdited) {
+ U->removeFromList();
+ if (auto *Assume = dyn_cast<IntrinsicInst>(U->getUser())) {
+ assert(Assume->getIntrinsicID() == Intrinsic::assume);
+ unsigned OpNo = U->getOperandNo();
+ if (OpNo == 0)
+ Assume->setOperand(0, ConstantInt::getTrue(Assume->getContext()));
+ else {
+ Assume->setOperand(OpNo, UndefValue::get(U->get()->getType()));
+ CallInst::BundleOpInfo &BOI = Assume->getBundleOpInfoForOperand(OpNo);
+ BOI.Tag = getContext().pImpl->getOrInsertBundleTag("ignore");
+ }
+ } else
+ llvm_unreachable("unkown droppable use");
+ }
+}
+
bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
// This can be computed either by scanning the instructions in BB, or by
// scanning the use list of this Value. Both lists can be very long, but
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -4322,7 +4322,8 @@
break;
case Intrinsic::assume: {
for (auto& Elem : Call.bundle_op_infos()) {
- Assert(Attribute::isExistingAttribute(Elem.Tag->getKey()),
+ Assert(Elem.Tag->getKey() == "ignore" ||
+ Attribute::isExistingAttribute(Elem.Tag->getKey()),
"tags must be valid attribute names");
Assert(Elem.End - Elem.Begin <= 2, "to many arguments");
Attribute::AttrKind Kind =
diff --git a/llvm/unittests/IR/KnowledgeRetentionTest.cpp b/llvm/unittests/IR/KnowledgeRetentionTest.cpp
--- a/llvm/unittests/IR/KnowledgeRetentionTest.cpp
+++ b/llvm/unittests/IR/KnowledgeRetentionTest.cpp
@@ -25,21 +25,17 @@
StringRef Head, StringRef Tail,
std::vector<std::pair<StringRef, llvm::function_ref<void(Instruction *)>>>
&Tests) {
- std::string IR;
- IR.append(Head.begin(), Head.end());
- for (auto &Elem : Tests)
+ for (auto &Elem : Tests) {
+ std::string IR;
+ IR.append(Head.begin(), Head.end());
IR.append(Elem.first.begin(), Elem.first.end());
- IR.append(Tail.begin(), Tail.end());
- LLVMContext C;
- SMDiagnostic Err;
- std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
- if (!Mod)
- Err.print("AssumeQueryAPI", errs());
- unsigned Idx = 0;
- for (Instruction &I : (*Mod->getFunction("test")->begin())) {
- if (Idx < Tests.size())
- Tests[Idx].second(&I);
- Idx++;
+ IR.append(Tail.begin(), Tail.end());
+ LLVMContext C;
+ SMDiagnostic Err;
+ std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
+ if (!Mod)
+ Err.print("AssumeQueryAPI", errs());
+ Elem.second(&*(Mod->getFunction("test")->begin()->begin()));
}
}
@@ -199,7 +195,32 @@
Attribute::AttrKind::Dereferenceable, 12, true);
}));
- /// Keep this test last as it modifies the function.
+ Tests.push_back(std::make_pair(
+ "call void @func1(i32* readnone align 32 "
+ "dereferenceable(48) noalias %P, i32* "
+ "align 8 dereferenceable(28) %P1, i32* align 64 "
+ "dereferenceable(4) "
+ "%P2, i32* nonnull align 16 dereferenceable(12) %P3)\n",
+ [](Instruction *I) {
+ CallInst *Assume = BuildAssumeFromInst(I);
+ Assume->insertBefore(I);
+ I->getOperand(1)->dropDroppableUses();
+ I->getOperand(2)->dropDroppableUses();
+ I->getOperand(3)->dropDroppableUses();
+ AssertMatchesExactlyAttributes(
+ Assume, I->getOperand(0),
+ "(readnone|align|dereferenceable|noalias)");
+ AssertMatchesExactlyAttributes(Assume, I->getOperand(1),
+ "");
+ AssertMatchesExactlyAttributes(Assume, I->getOperand(2),
+ "");
+ AssertMatchesExactlyAttributes(Assume, I->getOperand(3),
+ "");
+ AssertHasTheRightValue(Assume, I->getOperand(0),
+ Attribute::AttrKind::Alignment, 32, true);
+ AssertHasTheRightValue(Assume, I->getOperand(0),
+ Attribute::AttrKind::Dereferenceable, 48, true);
+ }));
Tests.push_back(std::make_pair(
"call void @func(i32* nonnull align 4 dereferenceable(16) %P, i32* align "
"8 noalias %P1)\n",