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

// fuseIntegerComparisons optimizes inequalities such as '1 <= x && x < 5',
// which can be optimized to 'unsigned(x-1) < 4'.
//
// Look for branch structure like:
//
//	p
//	|\
//	| b
//	|/ \
//	s0 s1
//
// In our example, p has control '1 <= x', b has control 'x < 5',
// and s0 and s1 are the if and else results of the comparison.
//
// This will be optimized into:
//
//	p
//	 \
//	  b
//	 / \
//	s0 s1
//
// where b has the combined control value 'unsigned(x-1) < 4'.
// Later passes will then fuse p and b.
func fuseIntegerComparisons(b *Block) bool { … }

// getConstIntArgIndex returns the index of the first argument that is a
// constant integer or -1 if no such argument exists.
func getConstIntArgIndex(v *Value) int { … }

// isSignedInequality reports whether op represents the inequality < or ≤
// in the signed domain.
func isSignedInequality(v *Value) bool { … }

// isUnsignedInequality reports whether op represents the inequality < or ≤
// in the unsigned domain.
func isUnsignedInequality(v *Value) bool { … }

func areMergeableInequalities(x, y *Value) bool { … }