Fix PR1850 by removing an unsafe transformation from VMCore/ConstantFold.cpp.
Reimplement the xform in Analysis/ConstantFolding.cpp where we can use
targetdata to validate that it is safe. While I'm in there, fix some const
correctness issues and generalize the interface to the "operand folder".
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44817 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 494c94e..8c39846 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -55,7 +55,8 @@
if (CE->getOpcode() == Instruction::GetElementPtr) {
// Cannot compute this if the element type of the pointer is missing size
// info.
- if (!cast<PointerType>(CE->getOperand(0)->getType())->getElementType()->isSized())
+ if (!cast<PointerType>(CE->getOperand(0)->getType())
+ ->getElementType()->isSized())
return false;
// If the base isn't a global+constant, we aren't either.
@@ -117,7 +118,7 @@
/// SymbolicallyEvaluateGEP - If we can symbolically evaluate the specified GEP
/// constant expression, do so.
-static Constant *SymbolicallyEvaluateGEP(Constant** Ops, unsigned NumOps,
+static Constant *SymbolicallyEvaluateGEP(Constant* const* Ops, unsigned NumOps,
const Type *ResultTy,
const TargetData *TD) {
Constant *Ptr = Ops[0];
@@ -181,7 +182,12 @@
else
return 0; // All operands not constant!
- return ConstantFoldInstOperands(I, &Ops[0], Ops.size(), TD);
+ if (const CmpInst *CI = dyn_cast<CmpInst>(I))
+ return ConstantFoldCompareInstOperands(CI->getPredicate(),
+ &Ops[0], Ops.size(), TD);
+ else
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
+ &Ops[0], Ops.size(), TD);
}
/// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
@@ -190,23 +196,19 @@
/// attempting to fold instructions like loads and stores, which have no
/// constant expression form.
///
-Constant *llvm::ConstantFoldInstOperands(const Instruction* I,
- Constant** Ops, unsigned NumOps,
+Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
+ Constant* const* Ops, unsigned NumOps,
const TargetData *TD) {
- unsigned Opc = I->getOpcode();
- const Type *DestTy = I->getType();
-
// Handle easy binops first.
- if (isa<BinaryOperator>(I)) {
+ if (Instruction::isBinaryOp(Opcode)) {
if (isa<ConstantExpr>(Ops[0]) || isa<ConstantExpr>(Ops[1]))
- if (Constant *C = SymbolicallyEvaluateBinop(I->getOpcode(), Ops[0],
- Ops[1], TD))
+ if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], TD))
return C;
- return ConstantExpr::get(Opc, Ops[0], Ops[1]);
+ return ConstantExpr::get(Opcode, Ops[0], Ops[1]);
}
- switch (Opc) {
+ switch (Opcode) {
default: return 0;
case Instruction::Call:
if (Function *F = dyn_cast<Function>(Ops[0]))
@@ -215,8 +217,7 @@
return 0;
case Instruction::ICmp:
case Instruction::FCmp:
- return ConstantExpr::getCompare(cast<CmpInst>(I)->getPredicate(), Ops[0],
- Ops[1]);
+ assert(0 &&"This function is invalid for compares: no predicate specified");
case Instruction::PtrToInt:
// If the input is a inttoptr, eliminate the pair. This requires knowing
// the width of a pointer, so it can't be done in ConstantExpr::getCast.
@@ -229,7 +230,7 @@
TD->getPointerSizeInBits()));
Input = ConstantExpr::getAnd(Input, Mask);
// Do a zext or trunc to get to the dest size.
- return ConstantExpr::getIntegerCast(Input, I->getType(), false);
+ return ConstantExpr::getIntegerCast(Input, DestTy, false);
}
}
// FALL THROUGH.
@@ -244,7 +245,7 @@
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::BitCast:
- return ConstantExpr::getCast(Opc, Ops[0], DestTy);
+ return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
case Instruction::Select:
return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
case Instruction::ExtractElement:
@@ -254,13 +255,73 @@
case Instruction::ShuffleVector:
return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
case Instruction::GetElementPtr:
- if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, I->getType(), TD))
+ if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, DestTy, TD))
return C;
return ConstantExpr::getGetElementPtr(Ops[0], Ops+1, NumOps-1);
}
}
+/// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
+/// instruction (icmp/fcmp) with the specified operands. If it fails, it
+/// returns a constant expression of the specified operands.
+///
+Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
+ Constant*const * Ops,
+ unsigned NumOps,
+ const TargetData *TD) {
+ // fold: icmp (inttoptr x), null -> icmp x, 0
+ // fold: icmp (ptrtoint x), 0 -> icmp x, null
+ // fold: icmp (inttoptr x), (inttoptr y) -> icmp x, y
+ // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y
+ //
+ // ConstantExpr::getCompare cannot do this, because it doesn't have TD
+ // around to know if bit truncation is happening.
+ if (ConstantExpr *CE0 = dyn_cast<ConstantExpr>(Ops[0])) {
+ if (TD && Ops[1]->isNullValue()) {
+ const Type *IntPtrTy = TD->getIntPtrType();
+ if (CE0->getOpcode() == Instruction::IntToPtr) {
+ // Convert the integer value to the right size to ensure we get the
+ // proper extension or truncation.
+ Constant *C = ConstantExpr::getIntegerCast(CE0->getOperand(0),
+ IntPtrTy, false);
+ Constant *NewOps[] = { C, Constant::getNullValue(C->getType()) };
+ return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD);
+ }
+
+ // Only do this transformation if the int is intptrty in size, otherwise
+ // there is a truncation or extension that we aren't modeling.
+ if (CE0->getOpcode() == Instruction::PtrToInt &&
+ CE0->getType() == IntPtrTy) {
+ Constant *C = CE0->getOperand(0);
+ Constant *NewOps[] = { C, Constant::getNullValue(C->getType()) };
+ // FIXME!
+ return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD);
+ }
+ }
+
+ if (TD && isa<ConstantExpr>(Ops[1]) &&
+ cast<ConstantExpr>(Ops[1])->getOpcode() == CE0->getOpcode()) {
+ const Type *IntPtrTy = TD->getIntPtrType();
+ // Only do this transformation if the int is intptrty in size, otherwise
+ // there is a truncation or extension that we aren't modeling.
+ if ((CE0->getOpcode() == Instruction::IntToPtr &&
+ CE0->getOperand(0)->getType() == IntPtrTy &&
+ CE0->getOperand(1)->getType() == IntPtrTy) ||
+ (CE0->getOpcode() == Instruction::PtrToInt &&
+ CE0->getType() == IntPtrTy &&
+ CE0->getOperand(0)->getType() == CE0->getOperand(1)->getType())) {
+ Constant *NewOps[] = {
+ CE0->getOperand(0), cast<ConstantExpr>(Ops[1])->getOperand(0)
+ };
+ return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD);
+ }
+ }
+ }
+ return ConstantExpr::getCompare(Predicate, Ops[0], Ops[1]);
+}
+
+
/// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
/// getelementptr constantexpr, return the constant value being addressed by the
/// constant expression, or null if something is funny and we can't decide.
@@ -438,7 +499,8 @@
/// with the specified arguments, returning null if unsuccessful.
Constant *
-llvm::ConstantFoldCall(Function *F, Constant** Operands, unsigned NumOperands) {
+llvm::ConstantFoldCall(Function *F,
+ Constant* const* Operands, unsigned NumOperands) {
const ValueName *NameVal = F->getValueName();
if (NameVal == 0) return 0;
const char *Str = NameVal->getKeyData();