[clang] [llvm] [clang] Avoid printing overly large integer/_BitInt numbers in static assertion failure diagnostics #71675 (PR #145053)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 4 16:48:05 PDT 2025
https://github.com/maramatias updated https://github.com/llvm/llvm-project/pull/145053
>From f58ea201585cb1b0128f97b9edb07f35621d81b0 Mon Sep 17 00:00:00 2001
From: Mara Matias <mara.matias1 at gmail.com>
Date: Wed, 18 Jun 2025 09:06:10 -0700
Subject: [PATCH 1/2] [clang] Avoid printing overly large integer/_BitInt
numbers in static assertion failure diagnostics #71675
---
clang/docs/ReleaseNotes.rst | 6 +++++-
clang/lib/Sema/SemaDeclCXX.cpp | 17 ++++++++++++++++-
clang/test/AST/ByteCode/intap.cpp | 8 ++++----
clang/test/Sema/enum.c | 2 +-
clang/test/SemaCXX/static-assert.cpp | 6 ++++++
5 files changed, 32 insertions(+), 7 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index bc8e157e2b1c0..9e48175700613 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -647,7 +647,11 @@ Improvements to Clang's diagnostics
#GH69470, #GH59391, #GH58172, #GH46215, #GH45915, #GH45891, #GH44490,
#GH36703, #GH32903, #GH23312, #GH69874.
-
+- Improved the performance of static assertions envolving large integers by
+ using hex format instead of string.
+
+ Fixes #GH71675
+
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 16645ecf411e5..71bf5f60d6e1b 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -47,6 +47,7 @@
#include "clang/Sema/SemaOpenMP.h"
#include "clang/Sema/Template.h"
#include "clang/Sema/TemplateDeduction.h"
+#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
@@ -17575,7 +17576,21 @@ static bool ConvertAPValueToString(const APValue &V, QualType T,
break;
}
}
- V.getInt().toString(Str);
+
+ llvm::APSInt vInt = V.getInt();
+ if (llvm::APSInt::compareValues(
+ vInt, llvm::APSInt::getUnsigned(
+ std::numeric_limits<uint64_t>::max())) >= 0 ||
+ vInt < std::numeric_limits<int64_t>::min()) {
+ // The value of cutSize is not special, it is just a number of
+ // characters that gives us enough info without losing readability.
+ const int cutSize = 20;
+ vInt.toString(Str, 16);
+ Str.erase(Str.begin() + cutSize, Str.end() - cutSize);
+ Str.insert(Str.begin() + cutSize, 3, '.');
+ } else {
+ vInt.toString(Str);
+ }
}
break;
diff --git a/clang/test/AST/ByteCode/intap.cpp b/clang/test/AST/ByteCode/intap.cpp
index 68883871ffd26..1381bba5050a2 100644
--- a/clang/test/AST/ByteCode/intap.cpp
+++ b/clang/test/AST/ByteCode/intap.cpp
@@ -87,12 +87,12 @@ typedef unsigned __int128 uint128_t;
static const __uint128_t UINT128_MAX =__uint128_t(__int128_t(-1L));
static_assert(UINT128_MAX == -1, "");
static_assert(UINT128_MAX == 1, ""); // both-error {{static assertion failed}} \
- // both-note {{'340282366920938463463374607431768211455 == 1'}}
+ // both-note {{'FFFFFFFFFFFFFFFFFFFF...FFFFFFFFFFFFFFFFFFFF == 1'}}
static const __int128_t INT128_MAX = UINT128_MAX >> (__int128_t)1;
static_assert(INT128_MAX != 0, "");
static_assert(INT128_MAX == 0, ""); // both-error {{failed}} \
- // both-note {{evaluates to '170141183460469231731687303715884105727 == 0'}}
+ // both-note {{evaluates to '7FFFFFFFFFFFFFFFFFFF...FFFFFFFFFFFFFFFFFFFF == 0'}}
static const __int128_t INT128_MIN = -INT128_MAX - 1;
@@ -113,14 +113,14 @@ namespace i128 {
static const __uint128_t UINT128_MAX =__uint128_t(__int128_t(-1L));
static_assert(UINT128_MAX == -1, "");
static_assert(UINT128_MAX == 1, ""); // both-error {{static assertion failed}} \
- // both-note {{'340282366920938463463374607431768211455 == 1'}}
+ // both-note {{'FFFFFFFFFFFFFFFFFFFF...FFFFFFFFFFFFFFFFFFFF == 1'}}
constexpr uint128_t TooMuch = UINT128_MAX * 2;
static const __int128_t INT128_MAX = UINT128_MAX >> (__int128_t)1;
static_assert(INT128_MAX != 0, "");
static_assert(INT128_MAX == 0, ""); // both-error {{failed}} \
- // both-note {{evaluates to '170141183460469231731687303715884105727 == 0'}}
+ // both-note {{evaluates to '7FFFFFFFFFFFFFFFFFFF...FFFFFFFFFFFFFFFFFFFF == 0'}}
constexpr int128_t TooMuch2 = INT128_MAX * INT128_MAX; // both-error {{must be initialized by a constant expression}} \
// both-note {{value 28948022309329048855892746252171976962977213799489202546401021394546514198529 is outside the range of representable}}
diff --git a/clang/test/Sema/enum.c b/clang/test/Sema/enum.c
index 01e41d4ebe956..80315a0c29b6a 100644
--- a/clang/test/Sema/enum.c
+++ b/clang/test/Sema/enum.c
@@ -196,7 +196,7 @@ enum GH59352 { // expected-warning {{enumeration values exceed range of largest
BigVal = 66666666666666666666wb
};
_Static_assert(BigVal == 66666666666666666666wb); /* expected-error {{static assertion failed due to requirement 'BigVal == 66666666666666666666wb'}}
- expected-note {{expression evaluates to '11326434445538011818 == 66666666666666666666'}}
+ expected-note {{expression evaluates to '11326434445538011818 == 39D2F941E420AAAAA<U+0000><U+0000><U+0000>...<U+0000><U+0000><U+0000>39D2F941E420AAAAA'}}
*/
_Static_assert(
_Generic(BigVal, // expected-error {{static assertion failed}}
diff --git a/clang/test/SemaCXX/static-assert.cpp b/clang/test/SemaCXX/static-assert.cpp
index bf6a2eeb432a3..4b9d23cb8c808 100644
--- a/clang/test/SemaCXX/static-assert.cpp
+++ b/clang/test/SemaCXX/static-assert.cpp
@@ -255,6 +255,12 @@ int f() {
}
}
+namespace GH71675 {
+constexpr unsigned _BitInt(__BITINT_MAXWIDTH__ >> 6) F = ~0; // expected-warning {{Clang extension}}
+static_assert(F == 1,""); // expected-error {{static assertion failed due to requirement 'F == 1'}} \
+ // expected-note {{expression evaluates to 'FFFFFFFFFFFFFFFFFFFF...FFFFFFFFFFFFFFFFFFFF == 1'}}
+} // namespace GH71675
+
namespace Diagnostics {
/// No notes for literals.
static_assert(false, ""); // expected-error {{failed}}
>From c60c2bf0be937d64e83da993a83e0aa4fc3f1bdb Mon Sep 17 00:00:00 2001
From: Mara Matias <mara.matias1 at gmail.com>
Date: Fri, 4 Jul 2025 16:19:32 -0700
Subject: [PATCH 2/2] fixup! [clang] Avoid printing overly large
integer/_BitInt numbers in static assertion failure diagnostics #71675
---
clang/docs/ReleaseNotes.rst | 4 ++--
clang/lib/Sema/SemaDeclCXX.cpp | 15 +--------------
clang/test/Sema/enum.c | 2 +-
clang/test/SemaCXX/static-assert.cpp | 6 +++++-
llvm/include/llvm/ADT/APInt.h | 11 +++++++++++
llvm/include/llvm/ADT/APSInt.h | 6 ++++++
llvm/lib/Support/APInt.cpp | 27 +++++++++++++++++++++++++++
7 files changed, 53 insertions(+), 18 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9e48175700613..8b069a1f7fe36 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -647,8 +647,8 @@ Improvements to Clang's diagnostics
#GH69470, #GH59391, #GH58172, #GH46215, #GH45915, #GH45891, #GH44490,
#GH36703, #GH32903, #GH23312, #GH69874.
-- Improved the performance of static assertions envolving large integers by
- using hex format instead of string.
+- Improved the performance of static assertions involving large integers by
+ using hex format instead of string for particularly large values.
Fixes #GH71675
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 71bf5f60d6e1b..218d50994ed86 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -17577,20 +17577,7 @@ static bool ConvertAPValueToString(const APValue &V, QualType T,
}
}
- llvm::APSInt vInt = V.getInt();
- if (llvm::APSInt::compareValues(
- vInt, llvm::APSInt::getUnsigned(
- std::numeric_limits<uint64_t>::max())) >= 0 ||
- vInt < std::numeric_limits<int64_t>::min()) {
- // The value of cutSize is not special, it is just a number of
- // characters that gives us enough info without losing readability.
- const int cutSize = 20;
- vInt.toString(Str, 16);
- Str.erase(Str.begin() + cutSize, Str.end() - cutSize);
- Str.insert(Str.begin() + cutSize, 3, '.');
- } else {
- vInt.toString(Str);
- }
+ V.getInt().toStringTruncated(Str);
}
break;
diff --git a/clang/test/Sema/enum.c b/clang/test/Sema/enum.c
index 80315a0c29b6a..01e41d4ebe956 100644
--- a/clang/test/Sema/enum.c
+++ b/clang/test/Sema/enum.c
@@ -196,7 +196,7 @@ enum GH59352 { // expected-warning {{enumeration values exceed range of largest
BigVal = 66666666666666666666wb
};
_Static_assert(BigVal == 66666666666666666666wb); /* expected-error {{static assertion failed due to requirement 'BigVal == 66666666666666666666wb'}}
- expected-note {{expression evaluates to '11326434445538011818 == 39D2F941E420AAAAA<U+0000><U+0000><U+0000>...<U+0000><U+0000><U+0000>39D2F941E420AAAAA'}}
+ expected-note {{expression evaluates to '11326434445538011818 == 66666666666666666666'}}
*/
_Static_assert(
_Generic(BigVal, // expected-error {{static assertion failed}}
diff --git a/clang/test/SemaCXX/static-assert.cpp b/clang/test/SemaCXX/static-assert.cpp
index 4b9d23cb8c808..2488e235d7f7e 100644
--- a/clang/test/SemaCXX/static-assert.cpp
+++ b/clang/test/SemaCXX/static-assert.cpp
@@ -258,7 +258,11 @@ int f() {
namespace GH71675 {
constexpr unsigned _BitInt(__BITINT_MAXWIDTH__ >> 6) F = ~0; // expected-warning {{Clang extension}}
static_assert(F == 1,""); // expected-error {{static assertion failed due to requirement 'F == 1'}} \
- // expected-note {{expression evaluates to 'FFFFFFFFFFFFFFFFFFFF...FFFFFFFFFFFFFFFFFFFF == 1'}}
+ // expected-note {{expression evaluates to '40141321820360630391...65812318570934173695 == 1'}}
+
+constexpr unsigned _BitInt(__BITINT_MAXWIDTH__) G = ~0; // expected-warning {{Clang extension}}
+static_assert(G == 1,""); // expected-error {{static assertion failed due to requirement 'G == 1'}} \
+ // expected-note {{expression evaluates to '...85551374411818336255 == 1'}}
} // namespace GH71675
namespace Diagnostics {
diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index 295506393a1c4..8cc8747bbedcd 100644
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -1686,6 +1686,17 @@ class [[nodiscard]] APInt {
bool UpperCase = true,
bool InsertSeparators = false) const;
+ /// Converts an APInt to a string and append it to Str. Str is commonly a
+ /// SmallString. If Radix > 10, UpperCase determine the case of letter
+ /// digits.
+ /// Very large numbers ar truncated and only the first and last 20 digits will
+ /// be added with an elipsis separating them.
+ LLVM_ABI void toStringTruncated(SmallVectorImpl<char> &Str, unsigned Radix,
+ bool Signed, bool truncate = true,
+ bool formatAsCLiteral = false,
+ bool UpperCase = true,
+ bool InsertSeparators = false) const;
+
/// Considers the APInt to be unsigned and converts it into a string in the
/// radix given. The radix can be 2, 8, 10 16, or 36.
void toStringUnsigned(SmallVectorImpl<char> &Str, unsigned Radix = 10) const {
diff --git a/llvm/include/llvm/ADT/APSInt.h b/llvm/include/llvm/ADT/APSInt.h
index 88a7a6e71c817..f3b5c79569301 100644
--- a/llvm/include/llvm/ADT/APSInt.h
+++ b/llvm/include/llvm/ADT/APSInt.h
@@ -86,6 +86,12 @@ class [[nodiscard]] APSInt : public APInt {
}
using APInt::toString;
+ void toStringTruncated(SmallVectorImpl<char> &Str,
+ unsigned Radix = 10) const {
+ APInt::toStringTruncated(Str, Radix, isSigned());
+ }
+ using APInt::toStringTruncated;
+
/// If this int is representable using an int64_t.
bool isRepresentableByInt64() const {
// For unsigned values with 64 active bits, they technically fit into a
diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp
index 954af7fff92a8..37e625c946f9d 100644
--- a/llvm/lib/Support/APInt.cpp
+++ b/llvm/lib/Support/APInt.cpp
@@ -2164,6 +2164,13 @@ void APInt::fromString(unsigned numbits, StringRef str, uint8_t radix) {
void APInt::toString(SmallVectorImpl<char> &Str, unsigned Radix, bool Signed,
bool formatAsCLiteral, bool UpperCase,
bool InsertSeparators) const {
+ toStringTruncated(Str, Radix, Signed, false, formatAsCLiteral, UpperCase,
+ InsertSeparators);
+}
+
+void APInt::toStringTruncated(SmallVectorImpl<char> &Str, unsigned Radix,
+ bool Signed, bool truncate, bool formatAsCLiteral,
+ bool UpperCase, bool InsertSeparators) const {
assert((Radix == 10 || Radix == 8 || Radix == 16 || Radix == 2 ||
Radix == 36) &&
"Radix should be 2, 8, 10, 16, or 36!");
@@ -2278,8 +2285,28 @@ void APInt::toString(SmallVectorImpl<char> &Str, unsigned Radix, bool Signed,
}
} else {
int Pos = 0;
+ // The value of cutOffSize is not special, it is just a number of
+ // characters that gives us enough info without losing readability.
+ constexpr int cutOffSize = 20;
while (Tmp.getBoolValue()) {
uint64_t Digit;
+ if (truncate && Pos == cutOffSize) {
+ unsigned numDigits = (int32_t)(Tmp.logBase2()/log2(Radix))+1;
+ if(numDigits-cutOffSize > 0) {
+ // Calculating pow of exponents over 300000 takes a long time.
+ // To keep note printing time short(under 3s), values with more digits
+ // will only return the last 20 digits.
+ if(numDigits < 300000) {
+ APInt divider = APIntOps::pow(APInt(Tmp.getBitWidth(),Radix),numDigits-cutOffSize);
+ Tmp = Tmp.udiv(divider);
+ Str.append(3,'.');
+ }
+ else {
+ Str.append(3,'.');
+ break;
+ }
+ }
+ }
udivrem(Tmp, Radix, Tmp, Digit);
assert(Digit < Radix && "divide failed");
if (InsertSeparators && Pos % Grouping == 0 && Pos > 0)
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