llvm-project

3ebfbac7 - [TableGen] Support for optional chain in Selection DAG nodes

[TableGen] Support for optional chain in Selection DAG nodes This change adds a new property for Selection DAG nodes used in pattern descriptions: SDNPMayHaveChain. A node with this property may have or may not have a chain operand. For example, both of the following variants become valid: t3: f32,ch = fnearbyint t0, t2 t3: f32 = fnearbyint t2 The specific variant is determined during pattern matching, based on whether the first operand is a chain (i.e. has the type MVT::Other). This feature is intended to be used for floating point operations. They have side effects in a strictfp environment and are pure functions in the default FP environment. Currently each such operation requires two opcodes - one for each kind of FP environment. These opcodes represent the same operation and are processed similarly, which increase amount of code. With this feature the support of strictfp environment should be easier, as it can use the same opcode as the default environment.