Make APFloat->int conversions deterministic even in
cases with undefined behavior.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42328 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp
index b3705f5..348b8ab 100644
--- a/lib/Support/APFloat.cpp
+++ b/lib/Support/APFloat.cpp
@@ -1399,13 +1399,28 @@
unsigned int msb, partsCount;
int bits;
- /* Handle the three special cases first. */
- if(category == fcInfinity || category == fcNaN)
- return opInvalidOp;
-
partsCount = partCountForBits(width);
- if(category == fcZero) {
+ /* Handle the three special cases first. We produce
+ a deterministic result even for the Invalid cases. */
+ if (category == fcNaN) {
+ // Neither sign nor isSigned affects this.
+ APInt::tcSet(parts, 0, partsCount);
+ return opInvalidOp;
+ }
+ if (category == fcInfinity) {
+ if (!sign && isSigned)
+ APInt::tcSetLeastSignificantBits(parts, partsCount, width-1);
+ else if (!sign && !isSigned)
+ APInt::tcSetLeastSignificantBits(parts, partsCount, width);
+ else if (sign && isSigned) {
+ APInt::tcSetLeastSignificantBits(parts, partsCount, 1);
+ APInt::tcShiftLeft(parts, partsCount, width-1);
+ } else // sign && !isSigned
+ APInt::tcSet(parts, 0, partsCount);
+ return opInvalidOp;
+ }
+ if (category == fcZero) {
APInt::tcSet(parts, 0, partsCount);
return opOK;
}
@@ -1418,6 +1433,19 @@
if(bits > 0) {
lost_fraction = tmp.shiftSignificandRight(bits);
} else {
+ if (-bits >= semantics->precision) {
+ // Unrepresentably large.
+ if (!sign && isSigned)
+ APInt::tcSetLeastSignificantBits(parts, partsCount, width-1);
+ else if (!sign && !isSigned)
+ APInt::tcSetLeastSignificantBits(parts, partsCount, width);
+ else if (sign && isSigned) {
+ APInt::tcSetLeastSignificantBits(parts, partsCount, 1);
+ APInt::tcShiftLeft(parts, partsCount, width-1);
+ } else // sign && !isSigned
+ APInt::tcSet(parts, 0, partsCount);
+ return (opStatus)(opOverflow | opInexact);
+ }
tmp.shiftSignificandLeft(-bits);
lost_fraction = lfExactlyZero;
}