aaron.ballman created this revision.
aaron.ballman added reviewers: mgehre-amd, erichkeane.
Herald added a project: All.
aaron.ballman requested review of this revision.
Herald added a project: clang.
@mgehre-amd pointed out the following post-commit review feedback on the
changes in 8cba72177dcd8de5d37177dbaf2347e5c1f0f1e8
<https://reviews.llvm.org/rG8cba72177dcd8de5d37177dbaf2347e5c1f0f1e8>:
As an example, the paper says 3wb /* Yields an _BitInt(3); two value bits,
one sign bit */.
So I would expect that 0xFwb gives _BitInt(5); four value bits, one sign bit,
but with this implementation I get _BitInt(2).
This is because ResultVal as 4 bits, and getMinSignedBits() inteprets it as
negative and thus says that 1 bit is enough to represent -1.
This corrects the behavior for calculating the bit-width and adds some test
coverage.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D122227
Files:
clang/lib/Sema/SemaExpr.cpp
clang/test/Lexer/bitint-constants.c
Index: clang/test/Lexer/bitint-constants.c
===================================================================
--- clang/test/Lexer/bitint-constants.c
+++ clang/test/Lexer/bitint-constants.c
@@ -142,3 +142,18 @@
0xFFFF'FFFF'FFFF'FFFF'FFFF'FFFF'FFFF'FFFF'1wb; // expected-error {{integer
literal is too large to be represented in any signed integer type}}
0xFFFF'FFFF'FFFF'FFFF'FFFF'FFFF'FFFF'FFFF'1uwb; // expected-error {{integer
literal is too large to be represented in any integer type}}
}
+
+void TestTypes(void) {
+ // 2 value bits, one sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(3wb), _BitInt(3)));
+ // 2 value bits, one sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(-3wb), _BitInt(3)));
+ // 2 value bits, no sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(3uwb), unsigned
_BitInt(2)));
+ // 4 value bits, one sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(0xFwb), _BitInt(5)));
+ // 4 value bits, one sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(-0xFwb), _BitInt(5)));
+ // 4 value bits, no sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(0xFuwb), unsigned
_BitInt(4)));
+}
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -3979,8 +3979,8 @@
if (Literal.isBitInt) {
// The signed version has one more bit for the sign value. There are no
// zero-width bit-precise integers, even if the literal value is 0.
- Width = Literal.isUnsigned ? std::max(ResultVal.getActiveBits(), 1u)
- : std::max(ResultVal.getMinSignedBits(),
2u);
+ Width = std::max(ResultVal.getActiveBits(), 1u) +
+ (Literal.isUnsigned ? 0u : 1u);
// Diagnose if the width of the constant is larger than
BITINT_MAXWIDTH,
// and reset the type to the largest supported width.
Index: clang/test/Lexer/bitint-constants.c
===================================================================
--- clang/test/Lexer/bitint-constants.c
+++ clang/test/Lexer/bitint-constants.c
@@ -142,3 +142,18 @@
0xFFFF'FFFF'FFFF'FFFF'FFFF'FFFF'FFFF'FFFF'1wb; // expected-error {{integer literal is too large to be represented in any signed integer type}}
0xFFFF'FFFF'FFFF'FFFF'FFFF'FFFF'FFFF'FFFF'1uwb; // expected-error {{integer literal is too large to be represented in any integer type}}
}
+
+void TestTypes(void) {
+ // 2 value bits, one sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(3wb), _BitInt(3)));
+ // 2 value bits, one sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(-3wb), _BitInt(3)));
+ // 2 value bits, no sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(3uwb), unsigned _BitInt(2)));
+ // 4 value bits, one sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(0xFwb), _BitInt(5)));
+ // 4 value bits, one sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(-0xFwb), _BitInt(5)));
+ // 4 value bits, no sign bit
+ _Static_assert(__builtin_types_compatible_p(__typeof__(0xFuwb), unsigned _BitInt(4)));
+}
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -3979,8 +3979,8 @@
if (Literal.isBitInt) {
// The signed version has one more bit for the sign value. There are no
// zero-width bit-precise integers, even if the literal value is 0.
- Width = Literal.isUnsigned ? std::max(ResultVal.getActiveBits(), 1u)
- : std::max(ResultVal.getMinSignedBits(), 2u);
+ Width = std::max(ResultVal.getActiveBits(), 1u) +
+ (Literal.isUnsigned ? 0u : 1u);
// Diagnose if the width of the constant is larger than BITINT_MAXWIDTH,
// and reset the type to the largest supported width.
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