From e7d9182a666a2a8f903bd330c82d7c623b783371 Mon Sep 17 00:00:00 2001 From: Simon Pilgrim Date: Sat, 22 Aug 2020 14:41:40 +0100 Subject: [PATCH] Enable constexpr on BITREVERSE builtin intrinsics (PR47249) This enables us to use the __builtin_bitreverse 8/16/32/64 intrinsics inside constexpr code. Differential Revision: https://reviews.llvm.org/D86339 --- clang/docs/LanguageExtensions.rst | 2 +- clang/docs/ReleaseNotes.rst | 4 ++++ clang/lib/AST/ExprConstant.cpp | 11 +++++++++++ clang/test/Sema/constant-builtins-2.c | 5 +++++ 4 files changed, 21 insertions(+), 1 deletion(-) diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst index fd563b0..a431239 100644 --- a/clang/docs/LanguageExtensions.rst +++ b/clang/docs/LanguageExtensions.rst @@ -1984,7 +1984,7 @@ Query for this feature with ``__has_builtin(__builtin_convertvector)``. The '``__builtin_bitreverse``' family of builtins is used to reverse the bitpattern of an integer value; for example ``0b10110110`` becomes -``0b01101101``. +``0b01101101``. These builtins can be used within constant expressions. ``__builtin_rotateleft`` ------------------------ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 7a94039..ba2b540 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -56,6 +56,10 @@ Improvements to Clang's diagnostics Non-comprehensive list of changes in this release ------------------------------------------------- +- The builtin intrinsics ``__builtin_bitreverse8``, ``__builtin_bitreverse16``, + ``__builtin_bitreverse32`` and ``__builtin_bitreverse64`` may now be used + within constant expressions. + - The builtin intrinsics ``__builtin_rotateleft8``, ``__builtin_rotateleft16``, ``__builtin_rotateleft32`` and ``__builtin_rotateleft64`` may now be used within constant expressions. diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 09ef562..c23233a 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -11180,6 +11180,17 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E, return Success(AlignedVal, E); } + case Builtin::BI__builtin_bitreverse8: + case Builtin::BI__builtin_bitreverse16: + case Builtin::BI__builtin_bitreverse32: + case Builtin::BI__builtin_bitreverse64: { + APSInt Val; + if (!EvaluateInteger(E->getArg(0), Val, Info)) + return false; + + return Success(Val.reverseBits(), E); + } + case Builtin::BI__builtin_bswap16: case Builtin::BI__builtin_bswap32: case Builtin::BI__builtin_bswap64: { diff --git a/clang/test/Sema/constant-builtins-2.c b/clang/test/Sema/constant-builtins-2.c index b0f566e..19d1599 100644 --- a/clang/test/Sema/constant-builtins-2.c +++ b/clang/test/Sema/constant-builtins-2.c @@ -169,6 +169,11 @@ char parity8[__builtin_parity(~0) == 0 ? 1 : -1]; char parity9[__builtin_parityl(1L << (BITSIZE(long) - 1)) == 1 ? 1 : -1]; char parity10[__builtin_parityll(1LL << (BITSIZE(long long) - 1)) == 1 ? 1 : -1]; +char bitreverse1[__builtin_bitreverse8(0x01) == 0x80 ? 1 : -1]; +char bitreverse2[__builtin_bitreverse16(0x3C48) == 0x123C ? 1 : -1]; +char bitreverse3[__builtin_bitreverse32(0x12345678) == 0x1E6A2C48 ? 1 : -1]; +char bitreverse4[__builtin_bitreverse64(0x0123456789ABCDEFULL) == 0xF7B3D591E6A2C480 ? 1 : -1]; + char rotateleft1[__builtin_rotateleft8(0x01, 5) == 0x20 ? 1 : -1]; char rotateleft2[__builtin_rotateleft16(0x3210, 11) == 0x8190 ? 1 : -1]; char rotateleft2[__builtin_rotateleft32(0x76543210, 22) == 0x841D950C ? 1 : -1]; -- 2.7.4