Skip to content

[APInt] Extend isSameValue to also do signed-compares #178854

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
artagnon merged 2 commits into from
Feb 1, 2026
Merged

[APInt] Extend isSameValue to also do signed-compares #178854

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
e34f5d3
[APInt] Introduce isSameSignedValue
artagnon Jan 30, 2026
c66495a
[APInt] Fold isSameSignedValue into isSameValue
artagnon Jan 30, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 11 additions & 5 deletions llvm/include/llvm/ADT/APInt.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -549,16 +549,22 @@ class [[nodiscard]] APInt {
/// \returns the low "numBits" bits of this APInt.
LLVM_ABI APInt getLoBits(unsigned numBits) const;

/// Determine if two APInts have the same value, after zero-extending
/// one of them (if needed!) to ensure that the bit-widths match.
static bool isSameValue(const APInt &I1, const APInt &I2) {
/// Determine if two APInts have the same value, after zero-extending or
/// sign-extending (if \p SignedCompare) one of them (if needed!) to ensure
/// that the bit-widths match.
static bool isSameValue(const APInt &I1, const APInt &I2,
bool SignedCompare = false) {
if (I1.getBitWidth() == I2.getBitWidth())
return I1 == I2;

auto ZExtOrSExt = [SignedCompare](const APInt &I, unsigned BitWidth) {
return SignedCompare ? I.sext(BitWidth) : I.zext(BitWidth);
};

if (I1.getBitWidth() > I2.getBitWidth())
return I1 == I2.zext(I1.getBitWidth());
return I1 == ZExtOrSExt(I2, I1.getBitWidth());

return I1.zext(I2.getBitWidth()) == I2;
return ZExtOrSExt(I1, I2.getBitWidth()) == I2;
}

/// Overload to compute a hash_code for an APInt value.
Expand Down
23 changes: 22 additions & 1 deletion llvm/unittests/ADT/APIntTest.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,6 @@
#include "llvm/Support/Alignment.h"
#include "gtest/gtest.h"
#include <array>
#include <climits>
#include <limits>
#include <optional>

Expand All @@ -29,6 +28,28 @@ TEST(APIntTest, ValueInit) {
EXPECT_TRUE(!Zero.sext(64));
}

TEST(APIntTest, IsSameValue) {
APInt One8(8, 1, /*isSigned=*/false);
APInt Three4(4, 3, /*isSigned=*/false);
EXPECT_FALSE(APInt::isSameValue(One8, Three4, /*SignedCompare=*/false));
EXPECT_FALSE(APInt::isSameValue(One8, Three4, /*SignedCompare=*/true));

APInt Two8(8, 2, /*isSigned=*/false);
APInt Two4(4, 2, /*isSigned=*/false);
EXPECT_TRUE(APInt::isSameValue(Two8, Two4, /*SignedCompare=*/false));
EXPECT_TRUE(APInt::isSameValue(Two8, Two4, /*SignedCompare=*/true));

APInt Seven8(8, 7, /*isSigned=*/false);
APInt Seven3(3, 7, /*isSigned=*/false);
EXPECT_TRUE(APInt::isSameValue(Seven8, Seven3, /*SignedCompare=*/false));
EXPECT_FALSE(APInt::isSameValue(Seven8, Seven3, /*SignedCompare=*/true));

APInt Ones8 = APInt::getAllOnes(8);
APInt Ones4 = APInt::getAllOnes(4);
EXPECT_FALSE(APInt::isSameValue(Ones8, Ones4, /*SignedCompare=*/false));
EXPECT_TRUE(APInt::isSameValue(Ones8, Ones4, /*SignedCompare=*/true));
}

// Test that 0^5 == 0
TEST(APIntTest, PowZeroTo5) {
APInt Zero = APInt::getZero(32);
Expand Down