[PATCH] D63691: [APInt] Fix getBitsNeeded for INT_MIN values
Dmitry Venikov via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 28 05:27:59 PDT 2019
Quolyk updated this revision to Diff 207044.
Quolyk added a comment.
Update
Repository:
rL LLVM
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D63691/new/
https://reviews.llvm.org/D63691
Files:
lib/Support/APInt.cpp
unittests/ADT/APIntTest.cpp
Index: unittests/ADT/APIntTest.cpp
===================================================================
--- unittests/ADT/APIntTest.cpp
+++ unittests/ADT/APIntTest.cpp
@@ -1263,8 +1263,21 @@
EXPECT_EQ(6U, APInt::getBitsNeeded("-19", 10));
EXPECT_EQ(6U, APInt::getBitsNeeded("-20", 10));
- // TODO: INT_MIN cases need 1 less bit (PR40897)
- EXPECT_EQ(9U, APInt::getBitsNeeded("-128", 10));
+ EXPECT_EQ(1U, APInt::getBitsNeeded("-1", 10));
+ EXPECT_EQ(2U, APInt::getBitsNeeded("-2", 10));
+ EXPECT_EQ(3U, APInt::getBitsNeeded("-4", 10));
+ EXPECT_EQ(4U, APInt::getBitsNeeded("-8", 10));
+ EXPECT_EQ(5U, APInt::getBitsNeeded("-16", 10));
+ EXPECT_EQ(6U, APInt::getBitsNeeded("-23", 10));
+ EXPECT_EQ(6U, APInt::getBitsNeeded("-32", 10));
+ EXPECT_EQ(7U, APInt::getBitsNeeded("-64", 10));
+ EXPECT_EQ(8U, APInt::getBitsNeeded("-127", 10));
+ EXPECT_EQ(8U, APInt::getBitsNeeded("-128", 10));
+ EXPECT_EQ(9U, APInt::getBitsNeeded("-255", 10));
+ EXPECT_EQ(9U, APInt::getBitsNeeded("-256", 10));
+ EXPECT_EQ(10U, APInt::getBitsNeeded("-512", 10));
+ EXPECT_EQ(11U, APInt::getBitsNeeded("-1024", 10));
+ EXPECT_EQ(12U, APInt::getBitsNeeded("-1025", 10));
}
TEST(APIntTest, StringBitsNeeded16) {
Index: lib/Support/APInt.cpp
===================================================================
--- lib/Support/APInt.cpp
+++ lib/Support/APInt.cpp
@@ -482,10 +482,13 @@
APInt tmp(sufficient, StringRef(p, slen), radix);
// Compute how many bits are required. If the log is infinite, assume we need
- // just bit.
+ // just bit. If the log is exact and value is negative, then the value is
+ // MinSignedValue with (log + 1) bits.
unsigned log = tmp.logBase2();
if (log == (unsigned)-1) {
return isNegative + 1;
+ } else if (isNegative && tmp.isPowerOf2()) {
+ return isNegative + log;
} else {
return isNegative + log + 1;
}
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