Author: Serge Pavlov Date: 2023-11-30T17:33:35+07:00 New Revision: e620035a28d5d957623aa7b4aeda35ab5130e2c9
URL: https://github.com/llvm/llvm-project/commit/e620035a28d5d957623aa7b4aeda35ab5130e2c9 DIFF: https://github.com/llvm/llvm-project/commit/e620035a28d5d957623aa7b4aeda35ab5130e2c9.diff LOG: [clang] Use current rounding mode for float inc/dec (#73770) Increment and decrement are equivalent to adding or subtracting 1. For the floating-point values these operations depend on the current rounding mode. Teach constant evaluator to perform ++ and -- according to the current floating-point environment. Pull request: https://github.com/llvm/llvm-project/pull/73770 Added: Modified: clang/lib/AST/ExprConstant.cpp clang/test/SemaCXX/rounding-math.cpp Removed: ################################################################################ diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 16697e5f076a8f8..2aafe5bd5289fc2 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -4623,11 +4623,13 @@ struct IncDecSubobjectHandler { if (Old) *Old = APValue(Value); APFloat One(Value.getSemantics(), 1); + llvm::RoundingMode RM = getActiveRoundingMode(Info, E); + APFloat::opStatus St; if (AccessKind == AK_Increment) - Value.add(One, APFloat::rmNearestTiesToEven); + St = Value.add(One, RM); else - Value.subtract(One, APFloat::rmNearestTiesToEven); - return true; + St = Value.subtract(One, RM); + return checkFloatingPointResult(Info, E, St); } bool foundPointer(APValue &Subobj, QualType SubobjType) { if (!checkConst(SubobjType)) diff --git a/clang/test/SemaCXX/rounding-math.cpp b/clang/test/SemaCXX/rounding-math.cpp index 73f9f10e6d59417..e7ead05041b560d 100644 --- a/clang/test/SemaCXX/rounding-math.cpp +++ b/clang/test/SemaCXX/rounding-math.cpp @@ -77,3 +77,24 @@ struct S1d { int f; }; static_assert(sizeof(S1d) == sizeof(int), ""); + +constexpr float incr_down(float k) { + float x = k; + ++x; + return x; +} + +// 0x1.0p23 = 8388608.0, inc(8388608.0) = 8388609.0 +static_assert(incr_down(0x1.0p23F) == 0x1.000002p23F, ""); +// 0x1.0p24 = 16777216.0, inc(16777216.0) = 16777217.0 -> round down -> 16777216.0 +static_assert(incr_down(0x1.0p24F) == 0x1.0p24F, ""); + +#pragma STDC FENV_ROUND FE_UPWARD +constexpr float incr_up(float k) { + float x = k; + ++x; + return x; +} +static_assert(incr_up(0x1.0p23F) == 0x1.000002p23F, ""); +// 0x1.0p24 = 16777216.0, inc(16777216.0) = 16777217.0 -> round up -> 16777218.0 +static_assert(incr_up(0x1.0p24F) == 0x1.000002p24F, ""); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits