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-rw-r--r--lib/IR/ConstantFold.cpp148
1 files changed, 99 insertions, 49 deletions
diff --git a/lib/IR/ConstantFold.cpp b/lib/IR/ConstantFold.cpp
index cdfb41f..a915d28 100644
--- a/lib/IR/ConstantFold.cpp
+++ b/lib/IR/ConstantFold.cpp
@@ -27,12 +27,14 @@
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Operator.h"
+#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MathExtras.h"
#include <limits>
using namespace llvm;
+using namespace llvm::PatternMatch;
//===----------------------------------------------------------------------===//
// ConstantFold*Instruction Implementations
@@ -913,49 +915,70 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
return C1;
return Constant::getNullValue(C1->getType()); // undef & X -> 0
case Instruction::Mul: {
- ConstantInt *CI;
- // X * undef -> undef if X is odd or undef
- if (((CI = dyn_cast<ConstantInt>(C1)) && CI->getValue()[0]) ||
- ((CI = dyn_cast<ConstantInt>(C2)) && CI->getValue()[0]) ||
- (isa<UndefValue>(C1) && isa<UndefValue>(C2)))
- return UndefValue::get(C1->getType());
+ // undef * undef -> undef
+ if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
+ return C1;
+ const APInt *CV;
+ // X * undef -> undef if X is odd
+ if (match(C1, m_APInt(CV)) || match(C2, m_APInt(CV)))
+ if ((*CV)[0])
+ return UndefValue::get(C1->getType());
// X * undef -> 0 otherwise
return Constant::getNullValue(C1->getType());
}
- case Instruction::UDiv:
case Instruction::SDiv:
+ case Instruction::UDiv:
+ // X / undef -> undef
+ if (match(C1, m_Zero()))
+ return C2;
+ // undef / 0 -> undef
// undef / 1 -> undef
- if (Opcode == Instruction::UDiv || Opcode == Instruction::SDiv)
- if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2))
- if (CI2->isOne())
- return C1;
- // FALL THROUGH
+ if (match(C2, m_Zero()) || match(C2, m_One()))
+ return C1;
+ // undef / X -> 0 otherwise
+ return Constant::getNullValue(C1->getType());
case Instruction::URem:
case Instruction::SRem:
- if (!isa<UndefValue>(C2)) // undef / X -> 0
- return Constant::getNullValue(C1->getType());
- return C2; // X / undef -> undef
+ // X % undef -> undef
+ if (match(C2, m_Undef()))
+ return C2;
+ // undef % 0 -> undef
+ if (match(C2, m_Zero()))
+ return C1;
+ // undef % X -> 0 otherwise
+ return Constant::getNullValue(C1->getType());
case Instruction::Or: // X | undef -> -1
if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef
return C1;
return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0
case Instruction::LShr:
- if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
- return C1; // undef lshr undef -> undef
- return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
- // undef lshr X -> 0
+ // X >>l undef -> undef
+ if (isa<UndefValue>(C2))
+ return C2;
+ // undef >>l 0 -> undef
+ if (match(C2, m_Zero()))
+ return C1;
+ // undef >>l X -> 0
+ return Constant::getNullValue(C1->getType());
case Instruction::AShr:
- if (!isa<UndefValue>(C2)) // undef ashr X --> all ones
- return Constant::getAllOnesValue(C1->getType());
- else if (isa<UndefValue>(C1))
- return C1; // undef ashr undef -> undef
- else
- return C1; // X ashr undef --> X
+ // X >>a undef -> undef
+ if (isa<UndefValue>(C2))
+ return C2;
+ // undef >>a 0 -> undef
+ if (match(C2, m_Zero()))
+ return C1;
+ // TODO: undef >>a X -> undef if the shift is exact
+ // undef >>a X -> 0
+ return Constant::getNullValue(C1->getType());
case Instruction::Shl:
- if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
- return C1; // undef shl undef -> undef
- // undef << X -> 0 or X << undef -> 0
+ // X << undef -> undef
+ if (isa<UndefValue>(C2))
+ return C2;
+ // undef << 0 -> undef
+ if (match(C2, m_Zero()))
+ return C1;
+ // undef << X -> 0
return Constant::getNullValue(C1->getType());
}
}
@@ -1259,15 +1282,17 @@ static int IdxCompare(Constant *C1, Constant *C2, Type *ElTy) {
if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
return -2; // don't know!
- // Ok, we have two differing integer indices. Sign extend them to be the same
- // type. Long is always big enough, so we use it.
- if (!C1->getType()->isIntegerTy(64))
- C1 = ConstantExpr::getSExt(C1, Type::getInt64Ty(C1->getContext()));
+ // We cannot compare the indices if they don't fit in an int64_t.
+ if (cast<ConstantInt>(C1)->getValue().getActiveBits() > 64 ||
+ cast<ConstantInt>(C2)->getValue().getActiveBits() > 64)
+ return -2; // don't know!
- if (!C2->getType()->isIntegerTy(64))
- C2 = ConstantExpr::getSExt(C2, Type::getInt64Ty(C1->getContext()));
+ // Ok, we have two differing integer indices. Sign extend them to be the same
+ // type.
+ int64_t C1Val = cast<ConstantInt>(C1)->getSExtValue();
+ int64_t C2Val = cast<ConstantInt>(C2)->getSExtValue();
- if (C1 == C2) return 0; // They are equal
+ if (C1Val == C2Val) return 0; // They are equal
// If the type being indexed over is really just a zero sized type, there is
// no pointer difference being made here.
@@ -1276,8 +1301,7 @@ static int IdxCompare(Constant *C1, Constant *C2, Type *ElTy) {
// If they are really different, now that they are the same type, then we
// found a difference!
- if (cast<ConstantInt>(C1)->getSExtValue() <
- cast<ConstantInt>(C2)->getSExtValue())
+ if (C1Val < C2Val)
return -1;
else
return 1;
@@ -1348,9 +1372,24 @@ static FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) {
static ICmpInst::Predicate areGlobalsPotentiallyEqual(const GlobalValue *GV1,
const GlobalValue *GV2) {
+ auto isGlobalUnsafeForEquality = [](const GlobalValue *GV) {
+ if (GV->hasExternalWeakLinkage() || GV->hasWeakAnyLinkage())
+ return true;
+ if (const auto *GVar = dyn_cast<GlobalVariable>(GV)) {
+ Type *Ty = GVar->getType()->getPointerElementType();
+ // A global with opaque type might end up being zero sized.
+ if (!Ty->isSized())
+ return true;
+ // A global with an empty type might lie at the address of any other
+ // global.
+ if (Ty->isEmptyTy())
+ return true;
+ }
+ return false;
+ };
// Don't try to decide equality of aliases.
if (!isa<GlobalAlias>(GV1) && !isa<GlobalAlias>(GV2))
- if (!GV1->hasExternalWeakLinkage() || !GV2->hasExternalWeakLinkage())
+ if (!isGlobalUnsafeForEquality(GV1) && !isGlobalUnsafeForEquality(GV2))
return ICmpInst::ICMP_NE;
return ICmpInst::BAD_ICMP_PREDICATE;
}
@@ -2040,8 +2079,7 @@ static Constant *ConstantFoldGetElementPtrImpl(Constant *C,
if (PerformFold) {
SmallVector<Value*, 16> NewIndices;
NewIndices.reserve(Idxs.size() + CE->getNumOperands());
- for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
- NewIndices.push_back(CE->getOperand(i));
+ NewIndices.append(CE->op_begin() + 1, CE->op_end() - 1);
// Add the last index of the source with the first index of the new GEP.
// Make sure to handle the case when they are actually different types.
@@ -2050,9 +2088,15 @@ static Constant *ConstantFoldGetElementPtrImpl(Constant *C,
if (!Idx0->isNullValue()) {
Type *IdxTy = Combined->getType();
if (IdxTy != Idx0->getType()) {
- Type *Int64Ty = Type::getInt64Ty(IdxTy->getContext());
- Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Int64Ty);
- Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, Int64Ty);
+ unsigned CommonExtendedWidth =
+ std::max(IdxTy->getIntegerBitWidth(),
+ Idx0->getType()->getIntegerBitWidth());
+ CommonExtendedWidth = std::max(CommonExtendedWidth, 64U);
+
+ Type *CommonTy =
+ Type::getIntNTy(IdxTy->getContext(), CommonExtendedWidth);
+ Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, CommonTy);
+ Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, CommonTy);
Combined = ConstantExpr::get(Instruction::Add, C1, C2);
} else {
Combined =
@@ -2125,14 +2169,20 @@ static Constant *ConstantFoldGetElementPtrImpl(Constant *C,
Constant *PrevIdx = cast<Constant>(Idxs[i-1]);
Constant *Div = ConstantExpr::getSDiv(CI, Factor);
+ unsigned CommonExtendedWidth =
+ std::max(PrevIdx->getType()->getIntegerBitWidth(),
+ Div->getType()->getIntegerBitWidth());
+ CommonExtendedWidth = std::max(CommonExtendedWidth, 64U);
+
// Before adding, extend both operands to i64 to avoid
// overflow trouble.
- if (!PrevIdx->getType()->isIntegerTy(64))
- PrevIdx = ConstantExpr::getSExt(PrevIdx,
- Type::getInt64Ty(Div->getContext()));
- if (!Div->getType()->isIntegerTy(64))
- Div = ConstantExpr::getSExt(Div,
- Type::getInt64Ty(Div->getContext()));
+ if (!PrevIdx->getType()->isIntegerTy(CommonExtendedWidth))
+ PrevIdx = ConstantExpr::getSExt(
+ PrevIdx,
+ Type::getIntNTy(Div->getContext(), CommonExtendedWidth));
+ if (!Div->getType()->isIntegerTy(CommonExtendedWidth))
+ Div = ConstantExpr::getSExt(
+ Div, Type::getIntNTy(Div->getContext(), CommonExtendedWidth));
NewIdxs[i-1] = ConstantExpr::getAdd(PrevIdx, Div);
} else {
generated by cgit v1.1 at 2025-01-07 06:32:41 +0000