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ReadOnlyGlobalVariables: don't convert external global vars to lets #66021

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Merged
merged 1 commit into from
May 20, 2023
Merged

ReadOnlyGlobalVariables: don't convert external global vars to lets #66021

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3 changes: 2 additions & 1 deletion SwiftCompilerSources/Sources/Optimizer/ModulePasses/ReadOnlyGlobalVariables.swift
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Expand Up @@ -35,7 +35,8 @@ let readOnlyGlobalVariablesPass = ModulePass(name: "read-only-global-variables")
}

for g in moduleContext.globalVariables {
if !g.isPossiblyUsedExternally,
if !g.isAvailableExternally,
!g.isPossiblyUsedExternally,
!g.isLet,
!writtenGlobals.contains(g) {
g.setIsLet(to: true, moduleContext)
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8 changes: 8 additions & 0 deletions SwiftCompilerSources/Sources/SIL/GlobalVariable.swift
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Expand Up @@ -35,6 +35,14 @@ final public class GlobalVariable : CustomStringConvertible, HasShortDescription
return bridged.isPossiblyUsedExternally()
}

/// True, if the linkage of the global indicates that it has a definition outside the
/// current compilation unit.
///
/// For example, `public_external` linkage.
public var isAvailableExternally: Bool {
return bridged.isAvailableExternally()
}

public var staticInitValue: SingleValueInstruction? {
bridged.getStaticInitializerValue().instruction as? SingleValueInstruction
}
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4 changes: 4 additions & 0 deletions include/swift/SIL/SILBridging.h
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Expand Up @@ -341,6 +341,10 @@ struct BridgedGlobalVar {
return getGlobal()->isPossiblyUsedExternally();
}

bool isAvailableExternally() const {
return swift::isAvailableExternally(getGlobal()->getLinkage());
}

SWIFT_IMPORT_UNSAFE
inline OptionalBridgedInstruction getStaticInitializerValue() const;

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10 changes: 4 additions & 6 deletions test/SILOptimizer/default-cmo.swift
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Expand Up @@ -12,18 +12,16 @@
import Module
import ModuleTBD

// CHECK-LABEL: sil_global public_external [let] @$s6Module0A6StructV22privateFunctionPointeryS2icvpZ : $@callee_guaranteed (Int) -> Int{{$}}
// CHECK-LABEL: sil_global public_external @$s6Module0A6StructV22privateFunctionPointeryS2icvpZ : $@callee_guaranteed (Int) -> Int{{$}}

public func callPublicFunctionPointer(_ x: Int) -> Int {
return Module.ModuleStruct.publicFunctionPointer(x)
}

// CHECK-LABEL: sil @$s4Main25callPublicFunctionPointeryS2iF :
// CHECK-NOT: global_addr
// CHECK-NOT: apply
// CHECK: builtin "sadd
// CHECK-NOT: global_addr
// CHECK-NOT: apply
// CHECK: global_addr
// CHECK: load
// CHECK: apply
// CHECK: } // end sil function '$s4Main25callPublicFunctionPointeryS2iF'
public func callPrivateFunctionPointer(_ x: Int) -> Int {
return Module.ModuleStruct.privateFunctionPointer(x)
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6 changes: 6 additions & 0 deletions test/SILOptimizer/read_only_global_vars.sil
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Expand Up @@ -23,6 +23,12 @@ sil_global @public_var : $Int32 = {
%initval = struct $Int32 (%0 : $Builtin.Int32)
}

// CHECK-LABEL: sil_global public_external @external_var : $Int32 = {
sil_global public_external @external_var : $Int32 = {
%0 = integer_literal $Builtin.Int32, 27
%initval = struct $Int32 (%0 : $Builtin.Int32)
}

sil @unknown_read_func : $@convention(thin) (@in Int32) -> ()

sil @read_var : $@convention(thin) (@inout Int32) -> Int32 {
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