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move logic for computing signed integer overflow when constant folding 

into APInt.

llvm-svn: 116453
This commit is contained in:
Chris Lattner 2010-10-13 23:46:56 +00:00
parent 79bdd88fa4
commit 2edb926880
1 changed files with 22 additions and 27 deletions
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49
clang/lib/Lex/PPExpressions.cpp
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@ -519,7 +519,6 @@ static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
RHS.Val.setIsUnsigned(Res.isUnsigned());
}
// FIXME: All of these should detect and report overflow??
bool Overflow = false;
switch (Operator) {
default: assert(0 && "Unknown operator token!");
@ -534,9 +533,10 @@ static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
break;
case tok::slash:
if (RHS.Val != 0) {
Res = LHS.Val / RHS.Val;
if (LHS.Val.isSigned()) // MININT/-1 --> overflow.
Overflow = LHS.Val.isMinSignedValue() && RHS.Val.isAllOnesValue();
if (LHS.Val.isSigned())
Res = llvm::APSInt(LHS.Val.sdiv_ov(RHS.Val, Overflow), false);
else
Res = LHS.Val / RHS.Val;
} else if (ValueLive) {
PP.Diag(OpLoc, diag::err_pp_division_by_zero)
<< LHS.getRange() << RHS.getRange();
@ -545,23 +545,22 @@ static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
break;
case tok::star:
Res = LHS.Val * RHS.Val;
if (Res.isSigned() && LHS.Val != 0 && RHS.Val != 0)
Overflow = Res/RHS.Val != LHS.Val || Res/LHS.Val != RHS.Val;
if (Res.isSigned())
Res = llvm::APSInt(LHS.Val.smul_ov(RHS.Val, Overflow), false);
else
Res = LHS.Val * RHS.Val;
break;
case tok::lessless: {
// Determine whether overflow is about to happen.
unsigned ShAmt = static_cast<unsigned>(RHS.Val.getLimitedValue());
if (ShAmt >= LHS.Val.getBitWidth())
Overflow = true, ShAmt = LHS.Val.getBitWidth()-1;
else if (LHS.isUnsigned())
Overflow = false;
else if (LHS.Val.isNonNegative()) // Don't allow sign change.
Overflow = ShAmt >= LHS.Val.countLeadingZeros();
else
Overflow = ShAmt >= LHS.Val.countLeadingOnes();
Res = LHS.Val << ShAmt;
if (LHS.isUnsigned()) {
Overflow = ShAmt >= LHS.Val.getBitWidth();
if (Overflow)
ShAmt = LHS.Val.getBitWidth()-1;
Res = LHS.Val << ShAmt;
} else {
Res = llvm::APSInt(LHS.Val.sshl_ov(ShAmt, Overflow), false);
}
break;
}
case tok::greatergreater: {
@ -573,20 +572,16 @@ static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
break;
}
case tok::plus:
Res = LHS.Val + RHS.Val;
if (LHS.isUnsigned())
Overflow = false;
else if (LHS.Val.isNonNegative() == RHS.Val.isNonNegative() &&
Res.isNonNegative() != LHS.Val.isNonNegative())
Overflow = true; // Overflow for signed addition.
Res = LHS.Val + RHS.Val;
else
Res = llvm::APSInt(LHS.Val.sadd_ov(RHS.Val, Overflow), false);
break;
case tok::minus:
Res = LHS.Val - RHS.Val;
if (LHS.isUnsigned())
Overflow = false;
else if (LHS.Val.isNonNegative() != RHS.Val.isNonNegative() &&
Res.isNonNegative() != LHS.Val.isNonNegative())
Overflow = true; // Overflow for signed subtraction.
Res = LHS.Val - RHS.Val;
else
Res = llvm::APSInt(LHS.Val.ssub_ov(RHS.Val, Overflow), false);
break;
case tok::lessequal:
Res = LHS.Val <= RHS.Val;