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add uadd_ov/usub_ov to apint, consolidate constant folding

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logic to use the new APInt methods.  Among other things this
implements rdar://8501501 - llvm.smul.with.overflow.i32 should constant fold

which comes from "clang -ftrapv", originally brought to my attention from PR8221.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116457 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2010-10-14 00:05:07 +00:00
parent 08e90f5646
commit eafc5cb80d
4 changed files with 54 additions and 35 deletions
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60
lib/Analysis/ConstantFolding.cpp
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@@ -1001,6 +1001,7 @@ llvm::canConstantFoldCallTo(const Function *F) {
case Intrinsic::usub_with_overflow:
case Intrinsic::sadd_with_overflow:
case Intrinsic::ssub_with_overflow:
case Intrinsic::smul_with_overflow:
case Intrinsic::convert_from_fp16:
case Intrinsic::convert_to_fp16:
return true;
@@ -1248,42 +1249,37 @@ llvm::ConstantFoldCall(Function *F,
if (ConstantInt *Op2 = dyn_cast<ConstantInt>(Operands[1])) {
switch (F->getIntrinsicID()) {
default: break;
case Intrinsic::uadd_with_overflow: {
Constant *Res = ConstantExpr::getAdd(Op1, Op2); // result.
case Intrinsic::sadd_with_overflow:
case Intrinsic::uadd_with_overflow:
case Intrinsic::ssub_with_overflow:
case Intrinsic::usub_with_overflow:
case Intrinsic::smul_with_overflow: {
APInt Res;
bool Overflow;
switch (F->getIntrinsicID()) {
default: assert(0 && "Invalid case");
case Intrinsic::sadd_with_overflow:
Res = Op1->getValue().sadd_ov(Op2->getValue(), Overflow);
break;
case Intrinsic::uadd_with_overflow:
Res = Op1->getValue().uadd_ov(Op2->getValue(), Overflow);
break;
case Intrinsic::ssub_with_overflow:
Res = Op1->getValue().ssub_ov(Op2->getValue(), Overflow);
break;
case Intrinsic::usub_with_overflow:
Res = Op1->getValue().usub_ov(Op2->getValue(), Overflow);
break;
case Intrinsic::smul_with_overflow:
Res = Op1->getValue().smul_ov(Op2->getValue(), Overflow);
break;
}
Constant *Ops[] = {
Res, ConstantExpr::getICmp(CmpInst::ICMP_ULT, Res, Op1) // overflow.
ConstantInt::get(F->getContext(), Res),
ConstantInt::get(Type::getInt1Ty(F->getContext()), Overflow)
};
return ConstantStruct::get(F->getContext(), Ops, 2, false);
}
case Intrinsic::usub_with_overflow: {
Constant *Res = ConstantExpr::getSub(Op1, Op2); // result.
Constant *Ops[] = {
Res, ConstantExpr::getICmp(CmpInst::ICMP_UGT, Res, Op1) // overflow.
};
return ConstantStruct::get(F->getContext(), Ops, 2, false);
}
case Intrinsic::sadd_with_overflow: {
Constant *Res = ConstantExpr::getAdd(Op1, Op2); // result.
Constant *Overflow = ConstantExpr::getSelect(
ConstantExpr::getICmp(CmpInst::ICMP_SGT,
ConstantInt::get(Op1->getType(), 0), Op1),
ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op2),
ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op2)); // overflow.
Constant *Ops[] = { Res, Overflow };
return ConstantStruct::get(F->getContext(), Ops, 2, false);
}
case Intrinsic::ssub_with_overflow: {
Constant *Res = ConstantExpr::getSub(Op1, Op2); // result.
Constant *Overflow = ConstantExpr::getSelect(
ConstantExpr::getICmp(CmpInst::ICMP_SGT,
ConstantInt::get(Op2->getType(), 0), Op2),
ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op1),
ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op1)); // overflow.
Constant *Ops[] = { Res, Overflow };
return ConstantStruct::get(F->getContext(), Ops, 2, false);
}
}
}