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teach ConstantRange that zero times X is always zero

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160317 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nuno Lopes 2012-07-16 20:47:16 +00:00
parent 98819c9d1e
commit 7e733eab2f
2 changed files with 14 additions and 0 deletions
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6
lib/Support/ConstantRange.cpp
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@ -537,6 +537,12 @@ ConstantRange::multiply(const ConstantRange &Other) const {
if (isEmptySet() || Other.isEmptySet())
return ConstantRange(getBitWidth(), /*isFullSet=*/false);
// If any of the operands is zero, then the result is also zero.
if ((getSingleElement() && *getSingleElement() == 0) ||
(Other.getSingleElement() && *Other.getSingleElement() == 0))
return ConstantRange(APInt(getBitWidth(), 0));
if (isFullSet() || Other.isFullSet())
return ConstantRange(getBitWidth(), /*isFullSet=*/true);

8
unittests/Support/ConstantRangeTest.cpp
View File

@ -382,6 +382,14 @@ TEST_F(ConstantRangeTest, Multiply) {
EXPECT_EQ(Some.multiply(Wrap), Full);
EXPECT_EQ(Wrap.multiply(Wrap), Full);
ConstantRange Zero(APInt(16, 0));
EXPECT_EQ(Zero.multiply(Full), Zero);
EXPECT_EQ(Zero.multiply(Some), Zero);
EXPECT_EQ(Zero.multiply(Wrap), Zero);
EXPECT_EQ(Full.multiply(Zero), Zero);
EXPECT_EQ(Some.multiply(Zero), Zero);
EXPECT_EQ(Wrap.multiply(Zero), Zero);
// http://llvm.org/PR4545
EXPECT_EQ(ConstantRange(APInt(4, 1), APInt(4, 6)).multiply(
ConstantRange(APInt(4, 6), APInt(4, 2))),