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[NFC][ValueTracking] Add OffsetZero into findAllocaForValue

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For StackLifetime after finding alloca we need to check that
values ponting to the begining of alloca.

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D86692
This commit is contained in:
Vitaly Buka 2020-08-27 13:45:39 -07:00
parent a7b8916a32
commit 4f88f9a474
3 changed files with 55 additions and 30 deletions
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10
include/llvm/Analysis/ValueTracking.h
View File

@ -413,10 +413,12 @@ constexpr unsigned MaxAnalysisRecursionDepth = 6;
bool getUnderlyingObjectsForCodeGen(const Value *V,
SmallVectorImpl<Value *> &Objects);
/// Finds alloca where the value comes from.
AllocaInst *findAllocaForValue(Value *V);
inline const AllocaInst *findAllocaForValue(const Value *V) {
return findAllocaForValue(const_cast<Value *>(V));
/// Returns unique alloca where the value comes from, or nullptr.
/// If OffsetZero is true check that V points to the begining of the alloca.
AllocaInst *findAllocaForValue(Value *V, bool OffsetZero = false);
inline const AllocaInst *findAllocaForValue(const Value *V,
bool OffsetZero = false) {
return findAllocaForValue(const_cast<Value *>(V), OffsetZero);
}
/// Return true if the only users of this pointer are lifetime markers.

36
lib/Analysis/ValueTracking.cpp
View File

@ -4331,7 +4331,8 @@ bool llvm::getUnderlyingObjectsForCodeGen(const Value *V,
}
static AllocaInst *
findAllocaForValue(Value *V, DenseMap<Value *, AllocaInst *> &AllocaForValue) {
findAllocaForValue(Value *V, DenseMap<Value *, AllocaInst *> &AllocaForValue,
bool OffsetZero) {
if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
return AI;
// See if we've already calculated (or started to calculate) alloca for a
@ -4344,36 +4345,41 @@ findAllocaForValue(Value *V, DenseMap<Value *, AllocaInst *> &AllocaForValue) {
AllocaForValue[V] = nullptr;
AllocaInst *Res = nullptr;
if (CastInst *CI = dyn_cast<CastInst>(V))
Res = findAllocaForValue(CI->getOperand(0), AllocaForValue);
else if (auto *SI = dyn_cast<SelectInst>(V)) {
Res = findAllocaForValue(SI->getTrueValue(), AllocaForValue);
if (!Res)
return nullptr;
AllocaInst *F = findAllocaForValue(SI->getFalseValue(), AllocaForValue);
if (F != Res)
return nullptr;
} else if (PHINode *PN = dyn_cast<PHINode>(V)) {
Res = findAllocaForValue(CI->getOperand(0), AllocaForValue, OffsetZero);
else if (PHINode *PN = dyn_cast<PHINode>(V)) {
for (Value *IncValue : PN->incoming_values()) {
// Allow self-referencing phi-nodes.
if (IncValue == PN)
continue;
AllocaInst *IncValueAI = findAllocaForValue(IncValue, AllocaForValue);
AllocaInst *IncValueAI =
findAllocaForValue(IncValue, AllocaForValue, OffsetZero);
// AI for incoming values should exist and should all be equal.
if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
return nullptr;
Res = IncValueAI;
}
} else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
Res = findAllocaForValue(EP->getPointerOperand(), AllocaForValue);
} else if (auto *SI = dyn_cast<SelectInst>(V)) {
Res = findAllocaForValue(SI->getTrueValue(), AllocaForValue, OffsetZero);
if (!Res)
return nullptr;
AllocaInst *F =
findAllocaForValue(SI->getFalseValue(), AllocaForValue, OffsetZero);
if (F != Res)
return nullptr;
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
if (OffsetZero && !GEP->hasAllZeroIndices())
return nullptr;
Res = findAllocaForValue(GEP->getPointerOperand(), AllocaForValue,
OffsetZero);
}
if (Res)
AllocaForValue[V] = Res;
return Res;
}
AllocaInst *llvm::findAllocaForValue(Value *V) {
AllocaInst *llvm::findAllocaForValue(Value *V, bool OffsetZero) {
DenseMap<Value *, AllocaInst *> AllocaForValue;
return ::findAllocaForValue(V, AllocaForValue);
return ::findAllocaForValue(V, AllocaForValue, OffsetZero);
}
static bool onlyUsedByLifetimeMarkersOrDroppableInstsHelper(

39
unittests/Analysis/ValueTrackingTest.cpp
View File

@ -1433,7 +1433,8 @@ TEST_F(ValueTrackingTest, ComputeConstantRange) {
struct FindAllocaForValueTestParams {
const char *IR;
bool Result;
bool AnyOffsetResult;
bool ZeroOffsetResult;
};
class FindAllocaForValueTest
@ -1449,7 +1450,7 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
%r = bitcast i64* %a to i32*
ret void
})",
true},
true, true},
{R"(
define void @test() {
@ -1457,7 +1458,15 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
%r = getelementptr i32, i32* %a, i32 1
ret void
})",
true},
true, false},
{R"(
define void @test() {
%a = alloca i32
%r = getelementptr i32, i32* %a, i32 0
ret void
})",
true, true},
{R"(
define void @test(i1 %cond) {
@ -1472,7 +1481,7 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
exit:
ret void
})",
true},
true, true},
{R"(
define void @test(i1 %cond) {
@ -1480,7 +1489,7 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
%r = select i1 %cond, i32* %a, i32* %a
ret void
})",
true},
true, true},
{R"(
define void @test(i1 %cond) {
@ -1489,7 +1498,7 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
%r = select i1 %cond, i32* %a, i32* %b
ret void
})",
false},
false, false},
{R"(
define void @test(i1 %cond) {
@ -1506,7 +1515,7 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
exit:
ret void
})",
true},
true, false},
{R"(
define void @test(i1 %cond) {
@ -1523,7 +1532,7 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
exit:
ret void
})",
false},
false, false},
{R"(
define void @test(i1 %cond, i64* %a) {
@ -1531,7 +1540,7 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
%r = bitcast i64* %a to i32*
ret void
})",
false},
false, false},
{R"(
define void @test(i1 %cond) {
@ -1547,7 +1556,7 @@ const FindAllocaForValueTestParams FindAllocaForValueTests[] = {
exit:
ret void
})",
false},
false, false},
};
TEST_P(FindAllocaForValueTest, findAllocaForValue) {
@ -1555,7 +1564,15 @@ TEST_P(FindAllocaForValueTest, findAllocaForValue) {
Function *F = M->getFunction("test");
Instruction *I = &findInstructionByName(F, "r");
const AllocaInst *AI = findAllocaForValue(I);
EXPECT_EQ(!!AI, GetParam().Result);
EXPECT_EQ(!!AI, GetParam().AnyOffsetResult);
}
TEST_P(FindAllocaForValueTest, findAllocaForValueZeroOffset) {
auto M = parseModule(GetParam().IR);
Function *F = M->getFunction("test");
Instruction *I = &findInstructionByName(F, "r");
const AllocaInst *AI = findAllocaForValue(I, true);
EXPECT_EQ(!!AI, GetParam().ZeroOffsetResult);
}
INSTANTIATE_TEST_CASE_P(FindAllocaForValueTest, FindAllocaForValueTest,