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Mark main() as used #33197

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Merged
merged 1 commit into from
Jul 31, 2020
Merged

Mark main() as used #33197

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12 changes: 2 additions & 10 deletions lib/IRGen/GenDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1908,11 +1908,7 @@ void irgen::updateLinkageForDefinition(IRGenModule &IGM,

// Everything externally visible is considered used in Swift.
// That mostly means we need to be good at not marking things external.
//
// Exclude "main", because it should naturally be used, and because adding it
// to llvm.used leaves a dangling use when the REPL attempts to discard
// intermediate mains.
if (LinkInfo::isUsed(IRL) && global->getName() != SWIFT_ENTRY_POINT_FUNCTION)
if (LinkInfo::isUsed(IRL))
IGM.addUsedGlobal(global);
}

Expand Down Expand Up @@ -2003,11 +1999,7 @@ llvm::Function *irgen::createFunction(IRGenModule &IGM,

// Everything externally visible is considered used in Swift.
// That mostly means we need to be good at not marking things external.
//
// Exclude "main", because it should naturally be used, and because adding it
// to llvm.used leaves a dangling use when the REPL attempts to discard
// intermediate mains.
if (linkInfo.isUsed() && name != SWIFT_ENTRY_POINT_FUNCTION) {
if (linkInfo.isUsed()) {
IGM.addUsedGlobal(fn);
}

Expand Down
14 changes: 12 additions & 2 deletions test/IRGen/unused.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@
// REQUIRES: CPU=x86_64

sil_stage canonical
import Builtin
import Swift

sil private @foo : $@convention(thin) () -> () {
bb0:
Expand Down Expand Up @@ -43,12 +45,20 @@ bb0:
return %1 : $()
}

// CHECK-macho: @llvm.used = appending global [2 x i8*] [i8* bitcast (void ()* @frieda to i8*), i8* bitcast (i16* @__swift_reflection_version to i8*)], section "llvm.metadata"
// CHECK-elf: @llvm.used = appending global [3 x i8*] [i8* bitcast (void ()* @frieda to i8*), i8* bitcast (i16* @__swift_reflection_version to i8*), i8* getelementptr inbounds ([0 x i8], [0 x i8]* @_swift1_autolink_entries, i32 0, i32 0)], section "llvm.metadata"
sil @main : $@convention(c) (Int32, UnsafeMutablePointer<Optional<UnsafeMutablePointer<Int8>>>) -> Int32 {
bb0(%0 : $Int32, %1 : $UnsafeMutablePointer<Optional<UnsafeMutablePointer<Int8>>>):
%2 = integer_literal $Builtin.Int32, 0 // user: %3
%3 = struct $Int32 (%2 : $Builtin.Int32) // user: %4
return %3 : $Int32 // id: %4
}

// CHECK-macho: @llvm.used = appending global [3 x i8*] [i8* bitcast (void ()* @frieda to i8*), i8* bitcast (i32 (i32, i8**)* @main to i8*), i8* bitcast (i16* @__swift_reflection_version to i8*)], section "llvm.metadata"
// CHECK-elf: @llvm.used = appending global [4 x i8*] [i8* bitcast (void ()* @frieda to i8*), i8* bitcast (i32 (i32, i8**)* @main to i8*), i8* bitcast (i16* @__swift_reflection_version to i8*), i8* getelementptr inbounds ([{{[0-9]+}} x i8], [{{[0-9]+}} x i8]* @_swift1_autolink_entries, i32 0, i32 0)], section "llvm.metadata"

// CHECK: define linkonce_odr hidden swiftcc void @qux()
// CHECK: define hidden swiftcc void @fred()
// CHECK: define{{( dllexport)?}}{{( protected)?}} swiftcc void @frieda()
// CHECK: define{{( dllexport)?}}{{( protected)?}} i32 @main

// NEGATIVE-NOT: @foo
// NEGATIVE-NOT: @bar
Expand Down