[APFloat] Ensure that we can properly parse strings that do not have null terminators.

rdar://14323230

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185397 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 33 insertions, 1 deletions

diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp
index a7ff9f6..ae4a101 100644
--- a/lib/Support/APFloat.cpp
+++ b/lib/Support/APFloat.cpp
@@ -2481,7 +2481,14 @@ APFloat::convertFromDecimalString(StringRef str, roundingMode rounding_mode)
            42039/12655 < L < 28738/8651  [ numerator <= 65536 ]
   */
 
-  if (decDigitValue(*D.firstSigDigit) >= 10U) {
+  // Test if we have a zero number allowing for strings with no null terminators
+  // and zero decimals with non-zero exponents.
+  // 
+  // We computed firstSigDigit by ignoring all zeros and dots. Thus if
+  // D->firstSigDigit equals str.end(), every digit must be a zero and there can
+  // be at most one dot. On the other hand, if we have a zero with a non-zero
+  // exponent, then we know that D.firstSigDigit will be non-numeric.
+  if (decDigitValue(*D.firstSigDigit) >= 10U || D.firstSigDigit == str.end()) {
     category = fcZero;
     fs = opOK;
 
diff --git a/unittests/ADT/APFloatTest.cpp b/unittests/ADT/APFloatTest.cpp
index d322bcd..46dfbd1 100644
--- a/unittests/ADT/APFloatTest.cpp
+++ b/unittests/ADT/APFloatTest.cpp
@@ -538,6 +538,31 @@ TEST(APFloatTest, Zero) {
   EXPECT_TRUE(APFloat(-0.0).isNegative());
 }
 
+TEST(APFloatTest, DecimalStringsWithoutNullTerminators) {
+  // Make sure that we can parse strings without null terminators.
+  // rdar://14323230.
+  APFloat Val(APFloat::IEEEdouble);
+  Val.convertFromString(StringRef("0.00", 3),
+                        llvm::APFloat::rmNearestTiesToEven);
+  EXPECT_EQ(Val.convertToDouble(), 0.0);
+  Val.convertFromString(StringRef("0.01", 3),
+                        llvm::APFloat::rmNearestTiesToEven);
+  EXPECT_EQ(Val.convertToDouble(), 0.0);
+  Val.convertFromString(StringRef("0.09", 3),
+                        llvm::APFloat::rmNearestTiesToEven);
+  EXPECT_EQ(Val.convertToDouble(), 0.0);
+  Val.convertFromString(StringRef("0.095", 4),
+                        llvm::APFloat::rmNearestTiesToEven);
+  EXPECT_EQ(Val.convertToDouble(), 0.09);
+  Val.convertFromString(StringRef("0.00e+3", 7),
+                        llvm::APFloat::rmNearestTiesToEven);
+  EXPECT_EQ(Val.convertToDouble(), 0.00);
+  Val.convertFromString(StringRef("0e+3", 4),
+                        llvm::APFloat::rmNearestTiesToEven);
+  EXPECT_EQ(Val.convertToDouble(), 0.00);
+
+}
+
 TEST(APFloatTest, fromZeroDecimalString) {
   EXPECT_EQ( 0.0, APFloat(APFloat::IEEEdouble,  "0").convertToDouble());
   EXPECT_EQ(+0.0, APFloat(APFloat::IEEEdouble, "+0").convertToDouble());