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ADT: Correct APInt::getActiveWords for zero values

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PR15138 was opened because of a segfault in the Bitcode writer.
The actual issue ended up being a bug in APInt where calls to
APInt::getActiveWords returns a bogus value when the APInt value
is 0.  This patch fixes the problem by ensuring that getActiveWords
returns 1 for 0 valued APInts.

llvm-svn: 174641
This commit is contained in:
Meador Inge
2013-02-07 18:36:50 +00:00
parent b31d71367b
commit 32dc724920
2 changed files with 10 additions and 1 deletions
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3
llvm/include/llvm/ADT/APInt.h
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@@ -1191,7 +1191,8 @@ public:
/// APInt. This is used in conjunction with getActiveData to extract the raw
/// value of the APInt.
unsigned getActiveWords() const {
return whichWord(getActiveBits()-1) + 1;
unsigned numActiveBits = getActiveBits();
return numActiveBits ? whichWord(numActiveBits - 1) + 1 : 1;
}
/// Computes the minimum bit width for this APInt while considering it to be

8
llvm/unittests/ADT/APIntTest.cpp
View File

@@ -56,6 +56,14 @@ TEST(APIntTest, i33_Count) {
#endif
TEST(APIntTest, i65_Count) {
APInt i65(65, 0, true);
EXPECT_EQ(65u, i65.countLeadingZeros());
EXPECT_EQ(0u, i65.countLeadingOnes());
EXPECT_EQ(0u, i65.getActiveBits());
EXPECT_EQ(1u, i65.getActiveWords());
EXPECT_EQ(65u, i65.countTrailingZeros());
EXPECT_EQ(0u, i65.countPopulation());
APInt i65minus(65, 0, true);
i65minus.setBit(64);
EXPECT_EQ(0u, i65minus.countLeadingZeros());