[ADT] Tighten static_assert in Bitfields

[kazutakahirata]

This patch tightens the static_assert. FirstBit and LastBit are
0-based bit indices of a bitfield, so they must be strictly less than
StorageBits.

[llvmbot]

@llvm/pr-subscribers-llvm-adt

Author: Kazu Hirata (kazutakahirata)

Changes

This patch tightens the static_assert. FirstBit and LastBit are
0-based bit indices of a bitfield, so they must be strictly less than
StorageBits.

---

Full diff: https://github.com/llvm/llvm-project/pull/165099.diff

1 Files Affected:

• (modified) llvm/include/llvm/ADT/Bitfields.h (+2-2)

diff --git a/llvm/include/llvm/ADT/Bitfields.h b/llvm/include/llvm/ADT/Bitfields.h
index 1fbc41c472581..be9546e9cc4cb 100644
--- a/llvm/include/llvm/ADT/Bitfields.h
+++ b/llvm/include/llvm/ADT/Bitfields.h
@@ -100,8 +100,8 @@ template <typename Bitfield, typename StorageType> struct Impl {
   using IntegerType = typename Bitfield::IntegerType;
 
   static constexpr size_t StorageBits = sizeof(StorageType) * CHAR_BIT;
-  static_assert(Bitfield::FirstBit <= StorageBits, "Data must fit in mask");
-  static_assert(Bitfield::LastBit <= StorageBits, "Data must fit in mask");
+  static_assert(Bitfield::FirstBit < StorageBits, "Data must fit in mask");
+  static_assert(Bitfield::LastBit < StorageBits, "Data must fit in mask");
   static constexpr StorageType LowMask =
       maskTrailingOnes<StorageType>(Bitfield::Bits);
   static constexpr StorageType Mask = LowMask << Bitfield::Shift;

[llvm-ci]

LLVM Buildbot has detected a new failure on builder ppc64le-mlir-rhel-clang running on ppc64le-mlir-rhel-test while building llvm at step 3 "clean-build-dir".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/129/builds/32187

Here is the relevant piece of the build log for the reference

Step 3 (clean-build-dir) failure: Delete failed. (failure) (timed out)
Step 6 (test-build-check-mlir-build-only-check-mlir) failure: 1200 seconds without output running [b'ninja', b'check-mlir'], attempting to kill
...
PASS: MLIR-Unit :: IR/./MLIRIRTests/101/130 (3598 of 3609)
PASS: MLIR :: Pass/pipeline-parsing.mlir (3599 of 3609)
PASS: MLIR-Unit :: IR/./MLIRIRTests/100/130 (3600 of 3609)
PASS: MLIR-Unit :: IR/./MLIRIRTests/38/130 (3601 of 3609)
PASS: MLIR-Unit :: IR/./MLIRIRTests/39/130 (3602 of 3609)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/11/22 (3603 of 3609)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/12/22 (3604 of 3609)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/13/22 (3605 of 3609)
PASS: MLIR-Unit :: IR/./MLIRIRTests/0/130 (3606 of 3609)
PASS: MLIR :: mlir-reduce/dce-test.mlir (3607 of 3609)
command timed out: 1200 seconds without output running [b'ninja', b'check-mlir'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=2195.575427

[llvm-ci]

LLVM Buildbot has detected a new failure on builder ppc64le-flang-rhel-clang running on ppc64le-flang-rhel-test while building llvm at step 6 "test-build-unified-tree-check-flang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/157/builds/41902

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-flang) failure: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
...
PASS: Flang :: Driver/linker-flags.f90 (3944 of 3954)
PASS: Flang :: Transforms/debug-line-table.fir (3945 of 3954)
PASS: Flang :: Lower/OpenMP/rtl-flags.f90 (3946 of 3954)
PASS: Flang :: Driver/use-module-error.f90 (3947 of 3954)
PASS: Flang :: Transforms/tbaa3.fir (3948 of 3954)
PASS: Flang :: Transforms/debug-dwarf-version.fir (3949 of 3954)
PASS: Flang :: Transforms/tbaa-local-alloc-threshold.fir (3950 of 3954)
PASS: Flang :: Driver/fopenmp.f90 (3951 of 3954)
PASS: Flang :: Driver/omp-driver-offload.f90 (3952 of 3954)
PASS: Flang :: Intrinsics/math-codegen.fir (3953 of 3954)
command timed out: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=3502.037892