go/src/cmd/compile/internal/ssa/fuse_branchredirect.go

// fuseBranchRedirect checks for a CFG in which the outbound branch
// of an If block can be derived from its predecessor If block, in
// some such cases, we can redirect the predecessor If block to the
// corresponding successor block directly. For example:
//
//	p:
//	  v11 = Less64 <bool> v10 v8
//	  If v11 goto b else u
//	b: <- p ...
//	  v17 = Leq64 <bool> v10 v8
//	  If v17 goto s else o
//
// We can redirect p to s directly.
//
// The implementation here borrows the framework of the prove pass.
//
//	1, Traverse all blocks of function f to find If blocks.
//	2,   For any If block b, traverse all its predecessors to find If blocks.
//	3,     For any If block predecessor p, update relationship p->b.
//	4,     Traverse all successors of b.
//	5,       For any successor s of b, try to update relationship b->s, if a
//	         contradiction is found then redirect p to another successor of b.
func fuseBranchRedirect(f *Func) bool { … }