llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Serge Pavlov (spavloff) <details> <summary>Changes</summary> 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. --- Full diff: https://github.com/llvm/llvm-project/pull/73770.diff 2 Files Affected: - (modified) clang/lib/AST/ExprConstant.cpp (+4-2) - (modified) clang/test/SemaCXX/rounding-math.cpp (+21) ``````````diff diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 16697e5f076a8f8..e0abe832c47a9f1 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -4623,10 +4623,12 @@ struct IncDecSubobjectHandler { if (Old) *Old = APValue(Value); APFloat One(Value.getSemantics(), 1); + llvm::RoundingMode RM = + E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode(); if (AccessKind == AK_Increment) - Value.add(One, APFloat::rmNearestTiesToEven); + Value.add(One, RM); else - Value.subtract(One, APFloat::rmNearestTiesToEven); + Value.subtract(One, RM); return true; } bool foundPointer(APValue &Subobj, QualType 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, ""); `````````` </details> https://github.com/llvm/llvm-project/pull/73770 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
