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[NFC][APInt] Add (exhaustive) test for multiplicativeInverse() 

Else there is no direct test coverage at all.
The function should either return '0' or precise answer.

llvm-svn: 364599
This commit is contained in:
Roman Lebedev 2019-06-27 21:51:54 +00:00
parent 4a8dc61534
commit a59cf87822
1 changed files with 17 additions and 0 deletions
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17
llvm/unittests/ADT/APIntTest.cpp
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@ -2505,4 +2505,21 @@ TEST(APIntTest, SolveQuadraticEquationWrap) {
Iterate(i);
}
TEST(APIntTest, MultiplicativeInverseExaustive) {
for (unsigned BitWidth = 1; BitWidth <= 16; ++BitWidth) {
for (unsigned Value = 0; Value < (1 << BitWidth); ++Value) {
APInt V = APInt(BitWidth, Value);
APInt MulInv =
V.zext(BitWidth + 1)
.multiplicativeInverse(APInt::getSignedMinValue(BitWidth + 1))
.trunc(BitWidth);
APInt One = V * MulInv;
EXPECT_TRUE(MulInv.isNullValue() || One.isOneValue())
<< " bitwidth = " << BitWidth << ", value = " << Value
<< ", computed multiplicative inverse = " << MulInv
<< ", value * multiplicative inverse = " << One << " (should be 1)";
}
}
}
} // end anonymous namespace