+
+ // If the user has permitted this code to choose the IEEE 754
+ // rounding at run-time, emit the rounding attribute.
+ if (TM.Options.HonorSignDependentRoundingFPMathOption)
+ ATS.emitAttribute(ARMBuildAttrs::ABI_FP_rounding,
+ ARMBuildAttrs::Allowed);
+ } else {
+ if (!Subtarget->hasVFP2()) {
+ // When the target doesn't have an FPU (by design or
+ // intention), the assumptions made on the software support
+ // mirror that of the equivalent hardware support *if it
+ // existed*. For v7 and better we indicate that denormals are
+ // flushed preserving sign, and for V6 we indicate that
+ // denormals are flushed to positive zero.
+ if (Subtarget->hasV7Ops())
+ ATS.emitAttribute(ARMBuildAttrs::ABI_FP_denormal,
+ ARMBuildAttrs::PreserveFPSign);
+ } else if (Subtarget->hasVFP3()) {
+ // In VFPv4, VFPv4U, VFPv3, or VFPv3U, it is preserved. That is,
+ // the sign bit of the zero matches the sign bit of the input or
+ // result that is being flushed to zero.
+ ATS.emitAttribute(ARMBuildAttrs::ABI_FP_denormal,
+ ARMBuildAttrs::PreserveFPSign);
+ }
+ // For VFPv2 implementations it is implementation defined as
+ // to whether denormals are flushed to positive zero or to
+ // whatever the sign of zero is (ARM v7AR ARM 2.7.5). Historically
+ // LLVM has chosen to flush this to positive zero (most likely for
+ // GCC compatibility), so that's the chosen value here (the
+ // absence of its emission implies zero).