low.scf.while

← low dialect

Condition-controlled target-low loop with explicit condition and body regions and loop-carried register state.

Operation contract

Property	Value
Semantic phase	executable
Traits	StorageRelation
Interfaces	LoopLike

Signature

Kind	Name	Type	Cardinality	Description
Operand	iter_args	register	variadic	Initial loop-carried register values.
Result	results	register	variadic	—
Region	before	region	required	Runs before each condition check. Terminated by low.scf.condition. (single block, terminator low.scf.condition.)
Region	after	region	required	Runs while the condition is true. Terminated by low.scf.yield. (single block, terminator low.scf.yield.)

Verification constraints

• IterArgsMatchResults(iter_args, results)
• BlockArgCount(before, iter_args)
• BlockArgsMatchTypes(before, iter_args)
• BlockArgCount(after, iter_args)
• BlockArgsMatchTypes(after, iter_args)
• ConditionForwardedCountMatchesBlockArgs(before, after, iter_args)
• ConditionForwardedTypesMatchBlockArgs(before, after, iter_args)
• YieldCountMatchesResults(after, results)
• YieldTypesMatchResults(after, results)

Examples

low.scf.while {
  low.scf.condition %condition : reg<spirv.id : i1>
} do {
  low.scf.yield
}

%result = low.scf.while(%before = %initial : reg<spirv.id : i32>) -> (reg<spirv.id : i32>) {
  low.scf.condition %keep_going, %before : reg<spirv.id : i1>, reg<spirv.id : i32>
} do(%body: reg<spirv.id : i32>) {
  low.scf.yield %body : reg<spirv.id : i32>
}