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[IRGen] Use llvm.used on ELF instead of llvm.compiler.used.
We changed to `llvm.compiler.used` because of the behaviour of `gold`, which refuses to coalesce sections that have different `SHF_GNU_RETAIN` flags, which causes problems with metadata. Originally I thought we were going to have to generate two sections with distinct names and have the runtime look for both of them, but it turns out that the runtime only wants to see sections that have `SHF_GNU_RETAIN` in any case. It's really the reflection code that is interested in being able to see non-retained sections. The upshot is that we don't need to use `llvm.compiler.used`; it's just fine if we have duplicate sections, as long as the reflection code looks for them when it's inspecting an ELF image. This also means we no longer need to pass `-z nostart-stop-gc` to the linker if we're using `lld`. rdar://123504095
1 parent d5e0ca5 commit aa15b23

10 files changed

+11
-35
lines changed

‎lib/Driver/UnixToolChains.cpp

Lines changed: 0 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -214,17 +214,6 @@ toolchains::GenericUnix::constructInvocation(const DynamicLinkJobAction &job,
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#else
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Arguments.push_back(context.Args.MakeArgString("-fuse-ld=" + Linker));
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#endif
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// Starting with lld 13, Swift stopped working with the lld --gc-sections
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// implementation for ELF, unless -z nostart-stop-gc is also passed to lld:
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//
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// https://reviews.llvm.org/D96914
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if (Linker == "lld" || (Linker.length() > 5 &&
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Linker.substr(Linker.length() - 6) == "ld.lld")) {
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Arguments.push_back("-Xlinker");
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Arguments.push_back("-z");
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Arguments.push_back("-Xlinker");
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Arguments.push_back("nostart-stop-gc");
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}
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}
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// Configure the toolchain.

‎lib/IRGen/GenDecl.cpp

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Original file line numberDiff line numberDiff line change
@@ -1030,15 +1030,6 @@ bool LinkInfo::isUsed(IRLinkage IRL) {
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///
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/// This value must have a definition by the time the module is finalized.
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void IRGenModule::addUsedGlobal(llvm::GlobalValue *global) {
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// As of reviews.llvm.org/D97448 "ELF: Create unique SHF_GNU_RETAIN sections
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// for llvm.used global objects" LLVM creates separate sections for globals in
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// llvm.used on ELF. Therefore we use llvm.compiler.used on ELF instead.
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if (TargetInfo.OutputObjectFormat == llvm::Triple::ELF) {
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addCompilerUsedGlobal(global);
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return;
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}
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LLVMUsed.push_back(global);
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}
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‎test/Distributed/distributed_actor_accessor_section_elf.swift

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -137,7 +137,7 @@ public distributed actor MyOtherActor {
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// CHECK-SAME: (ptr @"$s27distributed_actor_accessors12MyOtherActorC5emptyyyYaKFTETFTu" to i{{32|64}})
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// CHECK-SAME: , section "swift5_accessible_functions", {{.*}}
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// CHECK: @llvm.compiler.used = appending global [{{.*}} x ptr] [
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// CHECK: @llvm.used = appending global [{{.*}} x ptr] [
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// CHECK-SAME: @"$s27distributed_actor_accessors7MyActorC7simple1yySiYaKFTEHF"
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// CHECK-SAME: @"$s27distributed_actor_accessors7MyActorC7simple2ySSSiYaKFTEHF"
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// CHECK-SAME: @"$s27distributed_actor_accessors7MyActorC7simple3ySiSSYaKFTEHF"

‎test/Driver/link-time-opt.swift

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Original file line numberDiff line numberDiff line change
@@ -14,7 +14,6 @@
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// CHECK-SIMPLE-THIN-linux-gnu: clang
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// CHECK-SIMPLE-THIN-linux-gnu-DAG: -flto=thin
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// CHECK-SIMPLE-THIN-linux-gnu-DAG: -fuse-ld=lld
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// CHECK-SIMPLE-THIN-linux-gnu-DAG: -Xlinker -z -Xlinker nostart-stop-gc
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// CHECK-SIMPLE-THIN-linux-gnu-DAG: [[BITCODEFILE]]
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// CHECK-SIMPLE-THIN-linux-gnu-NOT: swift-autolink-extract
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@@ -36,7 +35,6 @@
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// CHECK-SIMPLE-FULL-linux-gnu: clang
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// CHECK-SIMPLE-FULL-linux-gnu-DAG: -flto=full
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// CHECK-SIMPLE-FULL-linux-gnu-DAG: -fuse-ld=lld
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// CHECK-SIMPLE-FULL-linux-gnu-DAG: -Xlinker -z -Xlinker nostart-stop-gc
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// CHECK-SIMPLE-FULL-linux-gnu-DAG: [[BITCODEFILE]]
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// CHECK-SIMPLE-FULL-linux-gnu-NOT: swift-autolink-extract
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‎test/IRGen/ELF-remove-autolink-section.swift

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Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
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print("Hi from Swift!")
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// ELF: @llvm.compiler.used = {{.*}}ptr @_swift1_autolink_entries
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// ELF: @llvm.used = {{.*}}ptr @_swift1_autolink_entries
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// SECTION: .swift1_autolink_entries
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// NOSECTION-NOT: .swift1_autolink_entries

‎test/IRGen/autolink_elf.swift

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Original file line numberDiff line numberDiff line change
@@ -10,5 +10,4 @@ import Empty
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// as used.
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// CHECK-DAG: @_swift1_autolink_entries = private constant [26 x i8] c"-lswiftEmpty\00-lanotherLib\00", section ".swift1_autolink_entries",{{.*}} align 8
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// CHECK-DAG: @llvm.compiler.used = appending global [{{.*}} x ptr] [{{.*}}ptr @_swift1_autolink_entries{{.*}}], section "llvm.metadata"
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// CHECK-DAG: @llvm.used = appending global [{{.*}} x ptr] [{{.*}}ptr @_swift1_autolink_entries{{.*}}], section "llvm.metadata"

‎test/IRGen/objc_protocol_vars.sil

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Original file line numberDiff line numberDiff line change
@@ -27,6 +27,5 @@ import Foundation
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}
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// CHECK-macho: @llvm.used = appending global [{{.*}}] [{{.*}}, ptr @"\01l_OBJC_LABEL_PROTOCOL_$__TtP18objc_protocol_vars1T_", ptr @"\01l_OBJC_PROTOCOL_REFERENCE_$__TtP18objc_protocol_vars1T_", {{.*}}], {{.*}}
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// CHECK-elf: @llvm.compiler.used = appending global [{{.*}}] [{{.*}}, ptr @"\01l_OBJC_LABEL_PROTOCOL_$__TtP18objc_protocol_vars1T_", ptr @"\01l_OBJC_PROTOCOL_REFERENCE_$__TtP18objc_protocol_vars1T_", {{.*}}], {{.*}}
30+
// CHECK-elf: @llvm.used = appending global [{{.*}}] [{{.*}}, ptr @"\01l_OBJC_LABEL_PROTOCOL_$__TtP18objc_protocol_vars1T_", ptr @"\01l_OBJC_PROTOCOL_REFERENCE_$__TtP18objc_protocol_vars1T_", {{.*}}], {{.*}}
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// CHECK-coff: @llvm.used = appending global [{{.*}}] [{{.*}}, ptr @"\01l_OBJC_LABEL_PROTOCOL_$__TtP18objc_protocol_vars1T_", ptr @"\01l_OBJC_PROTOCOL_REFERENCE_$__TtP18objc_protocol_vars1T_", {{.*}}], {{.*}}
32-

‎test/IRGen/section_asm.swift

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Original file line numberDiff line numberDiff line change
@@ -2,24 +2,24 @@
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// REQUIRES: swift_in_compiler
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// UNSUPPORTED: CPU=wasm32
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5-
// CHECK: .section{{.*}}__TEXT,__mysection
5+
// CHECK: .section{{.*}}"__TEXT,__mysection","ax"
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// CHECK-NOT: .section
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// CHECK: $s7section3fooyyF:
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// CHECK: .section{{.*}}__TEXT,__mysection
9+
// CHECK: .section{{.*}}"__TEXT,__mysection","ax"
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// CHECK-NOT: .section
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// CHECK: $s7section8MyStructV3fooyyF:
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13-
// CHECK: .section{{.*}}__DATA,__mysection
13+
// CHECK: .section{{.*}}"__DATA,__mysection","aw"
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// CHECK-NOT: .section
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// CHECK: $s7section2g0Sivp:
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// CHECK-NOT: .section
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// CHECK: $s7section2g1Si_Sitvp:
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// CHECK-NOT: .section
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// CHECK: $s7section2g2Sbvp:
20-
// CHECK-NOT: .section
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// CHECK: .section{{.*}}"__DATA,__mysection","awR"
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// CHECK: $s7section2g3Sbvp:
22-
// CHECK-NOT: .section
22+
// CHECK: .section{{.*}}"__DATA,__mysection","aw"
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// CHECK: $s7section2g4SpySiGSgvp:
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// CHECK-NOT: .section
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// CHECK: $s7section2g5SpySiGSgvp:

‎test/IRGen/unused.sil

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -56,7 +56,7 @@ bb0(%0 : $Int32, %1 : $UnsafeMutablePointer<Optional<UnsafeMutablePointer<Int8>>
5656
// CHECK-elf: @"\01l_entry_point" = private constant { i32, i32 } { i32 trunc (i64 sub (i64 ptrtoint (ptr @main to i64), i64 ptrtoint (ptr @"\01l_entry_point" to i64)) to i32), i32 0 }, section "swift5_entry", align 4
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5858
// CHECK-macho: @llvm.used = appending global [4 x ptr] [ptr @frieda, ptr @main, ptr @"\01l_entry_point", ptr @__swift_reflection_version], section "llvm.metadata"
59-
// CHECK-elf: @llvm.compiler.used = appending global [5 x ptr] [ptr @frieda, ptr @main, ptr @"\01l_entry_point", ptr @__swift_reflection_version, ptr @_swift1_autolink_entries], section "llvm.metadata"
59+
// CHECK-elf: @llvm.used = appending global [5 x ptr] [ptr @frieda, ptr @main, ptr @"\01l_entry_point", ptr @__swift_reflection_version, ptr @_swift1_autolink_entries], section "llvm.metadata"
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// CHECK: define linkonce_odr hidden swiftcc void @qux()
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// CHECK: define hidden swiftcc void @fred()

‎test/embedded/internalize-no-stdlib.swift

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Original file line numberDiff line numberDiff line change
@@ -26,7 +26,7 @@ public func main() {
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}
2727

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// CHECK-ELF: @_swift1_autolink_entries =
29-
// CHECK-ELF: @llvm.compiler.used = appending global [1 x ptr] [ptr @_swift1_autolink_entries], section "llvm.metadata"
29+
// CHECK-ELF: @llvm.used = appending global [1 x ptr] [ptr @_swift1_autolink_entries], section "llvm.metadata"
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// CHECK-ELF-NOT: @llvm.used
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// CHECK-MACHO-NOT: @llvm.compiler.used

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