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BooleanLiteralFolding: remove dead blocks #71339

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Merged
merged 1 commit into from
Feb 5, 2024
Merged

BooleanLiteralFolding: remove dead blocks #71339

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11 changes: 8 additions & 3 deletions SwiftCompilerSources/Sources/Optimizer/FunctionPasses/BooleanLiteralFolding.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -46,25 +46,30 @@ import SIL
let booleanLiteralFolding = FunctionPass(name: "boolean-literal-folding") {
(function: Function, context: FunctionPassContext) in

var changed = false
for block in function.blocks {
if let condBr = block.terminator as? CondBranchInst {
fold(condBranch: condBr, context)
changed = fold(condBranch: condBr, context) || changed
}
}
if changed {
_ = context.removeDeadBlocks(in: function)
}
}

private func fold(condBranch: CondBranchInst, _ context: FunctionPassContext) {
private func fold(condBranch: CondBranchInst, _ context: FunctionPassContext) -> Bool {
guard let structExtract = condBranch.condition as? StructExtractInst,
let initApply = structExtract.struct as? ApplyInst,
initApply.hasSemanticsAttribute("bool.literal_init"),
initApply.arguments.count == 2,
let literal = initApply.arguments[0] as? IntegerLiteralInst,
let literalValue = literal.value else
{
return
return false
}

let builder = Builder(before: condBranch, context)
builder.createBranch(to: literalValue == 0 ? condBranch.falseBlock : condBranch.trueBlock)
context.erase(instruction: condBranch)
return true
}
9 changes: 8 additions & 1 deletion test/SILOptimizer/boolean-literal-folding.sil
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Expand Up @@ -15,6 +15,9 @@ sil public_external [_semantics "bool.literal_init"] @wrong_bool_literal_init :
// CHECK: struct_extract
// CHECK-NEXT: br bb1
// CHECK: bb1:
// CHECK-NEXT: debug_step
// CHECK-NEXT: br bb2
// CHECK-NOT: bb3
// CHECK: } // end sil function 'replace_true'
sil [ossa] @replace_true : $@convention(thin) () -> () {
bb0:
Expand All @@ -25,6 +28,7 @@ bb0:
%4 = struct_extract %3 : $Bool, #Bool._value
cond_br %4, bb1, bb2
bb1:
debug_step
br bb3
bb2:
br bb3
Expand All @@ -35,8 +39,10 @@ bb3:

// CHECK-LABEL: sil [ossa] @replace_false :
// CHECK: struct_extract
// CHECK-NEXT: br bb2
// CHECK-NEXT: br bb1
// CHECK: bb1:
// CHECK-NEXT: br bb2
// CHECK-NOT: bb3
// CHECK: } // end sil function 'replace_false'
sil [ossa] @replace_false : $@convention(thin) () -> () {
bb0:
Expand All @@ -47,6 +53,7 @@ bb0:
%4 = struct_extract %3 : $Bool, #Bool._value
cond_br %4, bb1, bb2
bb1:
debug_step
br bb3
bb2:
br bb3
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6 changes: 3 additions & 3 deletions test/SILOptimizer/discard_checking.swift
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Expand Up @@ -33,15 +33,15 @@ struct Basics: ~Copyable {
repeat {
switch c {
case .red:
fatalError("bah!") // expected-error {{must consume 'self' before exiting method that discards self}}
fatalError("bah!")
case .blue:
throw E.someError // expected-error {{must consume 'self' before exiting method that discards self}}
throw E.someError
case .green:
self = Basics()
default: print("hi")
}
} while true
discard self // expected-note 2{{discarded self here}}
discard self
}

consuming func test2_fixed(_ c: Color) throws {
Expand Down