https://github.com/MaxGraey updated https://github.com/llvm/llvm-project/pull/189160
>From 88ca557592ed9e5b6a6be515f3fdef97d7157ac8 Mon Sep 17 00:00:00 2001 From: MaxGraey <[email protected]> Date: Sat, 28 Mar 2026 14:30:04 +0200 Subject: [PATCH 1/4] optimize NextPowerOf2 --- llvm/include/llvm/Support/MathExtras.h | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/llvm/include/llvm/Support/MathExtras.h b/llvm/include/llvm/Support/MathExtras.h index de2813094a950..59e7e40b742aa 100644 --- a/llvm/include/llvm/Support/MathExtras.h +++ b/llvm/include/llvm/Support/MathExtras.h @@ -370,14 +370,10 @@ constexpr uint64_t MinAlign(uint64_t A, uint64_t B) { /// Returns the next power of two (in 64-bits) that is strictly greater than A. /// Returns zero on overflow. -constexpr uint64_t NextPowerOf2(uint64_t A) { - A |= (A >> 1); - A |= (A >> 2); - A |= (A >> 4); - A |= (A >> 8); - A |= (A >> 16); - A |= (A >> 32); - return A + 1; +inline uint64_t NextPowerOf2(uint64_t A) { + if (A > UINT64_MAX / 2) + return 0; + return UINT64_C(1) << Log2_64_Ceil(A + 1); } /// Returns the power of two which is greater than or equal to the given value. >From 018b4ca86510dff8e80571aa449bd205bf1510dd Mon Sep 17 00:00:00 2001 From: MaxGraey <[email protected]> Date: Sat, 28 Mar 2026 14:56:54 +0200 Subject: [PATCH 2/4] add NextPowerOf2Constexpr --- llvm/include/llvm/ADT/BitmaskEnum.h | 2 +- llvm/include/llvm/Support/MathExtras.h | 13 +++++++++++++ llvm/include/llvm/Support/TypeSize.h | 2 +- 3 files changed, 15 insertions(+), 2 deletions(-) diff --git a/llvm/include/llvm/ADT/BitmaskEnum.h b/llvm/include/llvm/ADT/BitmaskEnum.h index c10a38c8ce4cb..53fae55e2c1ea 100644 --- a/llvm/include/llvm/ADT/BitmaskEnum.h +++ b/llvm/include/llvm/ADT/BitmaskEnum.h @@ -126,7 +126,7 @@ namespace BitmaskEnumDetail { template <typename E> constexpr std::underlying_type_t<E> Mask() { // On overflow, NextPowerOf2 returns zero with the type uint64_t, so // subtracting 1 gives us the mask with all bits set, like we want. - return NextPowerOf2(largest_bitmask_enum_bit<E>::value) - 1; + return NextPowerOf2Constexpr(largest_bitmask_enum_bit<E>::value) - 1; } /// Check that Val is in range for E, and return Val cast to E's underlying diff --git a/llvm/include/llvm/Support/MathExtras.h b/llvm/include/llvm/Support/MathExtras.h index 59e7e40b742aa..321ddf3329806 100644 --- a/llvm/include/llvm/Support/MathExtras.h +++ b/llvm/include/llvm/Support/MathExtras.h @@ -368,6 +368,19 @@ constexpr uint64_t MinAlign(uint64_t A, uint64_t B) { return (A | B) & (1 + ~(A | B)); } +/// Returns the next power of two (in 64-bits) that is strictly greater than A. +/// A constexpr version of NextPowerOf2. +/// Returns zero on overflow. +constexpr uint64_t NextPowerOf2Constexpr(uint64_t A) { + A |= (A >> 1); + A |= (A >> 2); + A |= (A >> 4); + A |= (A >> 8); + A |= (A >> 16); + A |= (A >> 32); + return A + 1; +} + /// Returns the next power of two (in 64-bits) that is strictly greater than A. /// Returns zero on overflow. inline uint64_t NextPowerOf2(uint64_t A) { diff --git a/llvm/include/llvm/Support/TypeSize.h b/llvm/include/llvm/Support/TypeSize.h index 421d6613bfafc..0a6e285935e1e 100644 --- a/llvm/include/llvm/Support/TypeSize.h +++ b/llvm/include/llvm/Support/TypeSize.h @@ -259,7 +259,7 @@ template <typename LeafTy, typename ValueTy> class FixedOrScalableQuantity { constexpr LeafTy coefficientNextPowerOf2() const { return LeafTy::get( - static_cast<ScalarTy>(llvm::NextPowerOf2(getKnownMinValue())), + static_cast<ScalarTy>(llvm::NextPowerOf2Constexpr(getKnownMinValue())), isScalable()); } >From e43d871333b6b9d0a254598bdc0d09b1791bbc75 Mon Sep 17 00:00:00 2001 From: MaxGraey <[email protected]> Date: Sat, 28 Mar 2026 15:36:10 +0200 Subject: [PATCH 3/4] fixes --- .../clang/DependencyScanning/DependencyScanningService.h | 2 +- flang/lib/Parser/openmp-parsers.cpp | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/clang/include/clang/DependencyScanning/DependencyScanningService.h b/clang/include/clang/DependencyScanning/DependencyScanningService.h index 0575dbc7cca9a..407de737f1468 100644 --- a/clang/include/clang/DependencyScanning/DependencyScanningService.h +++ b/clang/include/clang/DependencyScanning/DependencyScanningService.h @@ -46,7 +46,7 @@ enum class ScanningOutputFormat { }; #define DSS_LAST_BITMASK_ENUM(Id) \ - LLVM_MARK_AS_BITMASK_ENUM(Id), All = llvm::NextPowerOf2(Id) - 1 + LLVM_MARK_AS_BITMASK_ENUM(Id), All = llvm::NextPowerOf2Constexpr(Id) - 1 enum class ScanningOptimizations { None = 0, diff --git a/flang/lib/Parser/openmp-parsers.cpp b/flang/lib/Parser/openmp-parsers.cpp index 3b5d43db56ec2..4978ce66942b9 100644 --- a/flang/lib/Parser/openmp-parsers.cpp +++ b/flang/lib/Parser/openmp-parsers.cpp @@ -44,7 +44,7 @@ namespace Fortran::parser { using namespace Fortran::parser::omp; using DirectiveSet = - llvm::Bitset<llvm::NextPowerOf2(llvm::omp::Directive_enumSize)>; + llvm::Bitset<llvm::NextPowerOf2Constexpr(llvm::omp::Directive_enumSize)>; // Helper function to print the buffer contents starting at the current point. [[maybe_unused]] static std::string ahead(const ParseState &state) { >From 1933a57bca464a35dd7d1349e4f475e013527325 Mon Sep 17 00:00:00 2001 From: MaxGraey <[email protected]> Date: Tue, 31 Mar 2026 16:46:59 +0300 Subject: [PATCH 4/4] use countl_zero_constexpr for NextPowerOf2Constexpr --- llvm/include/llvm/Support/MathExtras.h | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/llvm/include/llvm/Support/MathExtras.h b/llvm/include/llvm/Support/MathExtras.h index 321ddf3329806..22fa8e6ebc783 100644 --- a/llvm/include/llvm/Support/MathExtras.h +++ b/llvm/include/llvm/Support/MathExtras.h @@ -372,13 +372,9 @@ constexpr uint64_t MinAlign(uint64_t A, uint64_t B) { /// A constexpr version of NextPowerOf2. /// Returns zero on overflow. constexpr uint64_t NextPowerOf2Constexpr(uint64_t A) { - A |= (A >> 1); - A |= (A >> 2); - A |= (A >> 4); - A |= (A >> 8); - A |= (A >> 16); - A |= (A >> 32); - return A + 1; + if (A > UINT64_MAX / 2) + return 0; + return UINT64_C(1) << (64 - llvm::countl_zero_constexpr(A)); } /// Returns the next power of two (in 64-bits) that is strictly greater than A. _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
