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[RelLookupTableConverter] Drop unnamed_addr to avoid generating GOTPCREL relocations #142304

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Merged
dianqk merged 3 commits into from
Jun 1, 2025
Merged

[RelLookupTableConverter] Drop unnamed_addr to avoid generating GOTPCREL relocations #142304

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dianqk Jun 1, 2025
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[RelLookupTableConverter] Drop unnamed_addr to avoid generating GOTPC…
dianqk Jun 1, 2025
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dianqk Jun 1, 2025
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5 changes: 5 additions & 0 deletions llvm/lib/Transforms/Utils/RelLookupTableConverter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -110,6 +110,11 @@ static GlobalVariable *createRelLookupTable(Function &Func,

for (Use &Operand : LookupTableArr->operands()) {
Constant *Element = cast<Constant>(Operand);
// Drop unnamed_addr to avoid matching pattern in
// `handleIndirectSymViaGOTPCRel`, which generates GOTPCREL relocations not
// supported by the GNU linker and LLD versions below 18 on aarch64.
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@nikic nikic Jun 1, 2025

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As we are working around problems with specific linkers on specific platforms, we should add triple checks like you originally had, for aarch64 and for x86-darwin (and list which linker versions are affected, so this can be removed in the future).

Does BFD not support GOTPCREL on aarch64 even in the newest version?

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@dianqk dianqk Jun 1, 2025

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Does BFD not support GOTPCREL on aarch64 even in the newest version?

Probably nobody noticed this.

 /nix/...-binutils-aarch64-unknown-linux-gnu-2.44/bin/ld: /path/1.rcgu.o: unrecognized relocation type 0x13b in section `.rodata..Lswitch.table.bad.rel'
          /nix/...-binutils-aarch64-unknown-linux-gnu-2.44/bin/ld: is this version of the linker - (GNU Binutils) 2.44 - out of date ?
          /nix/...-binutils-aarch64-unknown-linux-gnu-2.44/bin/ld: final link failed: bad value
          collect2: error: ld returned 1 exit status

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@nikic nikic Jun 1, 2025

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Huh. It would be good to file a bug for that...

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@dianqk dianqk Jun 1, 2025

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Huh. It would be good to file a bug for that...

I'm still in the process of creating an account. :\ (https://sourceware.org/bugzilla/createaccount.cgi)

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@dianqk dianqk Jun 2, 2025

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Filed: https://sourceware.org/bugzilla/show_bug.cgi?id=33043.

if (auto *GlobalElement = dyn_cast<GlobalValue>(Element))
GlobalElement->setUnnamedAddr(GlobalValue::UnnamedAddr::None);
Type *IntPtrTy = M.getDataLayout().getIntPtrType(M.getContext());
Constant *Base = llvm::ConstantExpr::getPtrToInt(RelLookupTable, IntPtrTy);
Constant *Target = llvm::ConstantExpr::getPtrToInt(Element, IntPtrTy);
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88 changes: 88 additions & 0 deletions llvm/test/Transforms/RelLookupTableConverter/unnamed_addr.ll
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@nikic nikic Jun 1, 2025

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Need REQUIRES: x86-registered-target and REQUIRES: aarch64-registered-target.

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@dianqk dianqk Jun 1, 2025

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Oops, added: de7f2fb

Original file line number Diff line number Diff line change
@@ -0,0 +1,88 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals all --version 5
; RUN: opt < %s -passes=rel-lookup-table-converter -relocation-model=pic -mtriple=x86_64 -S | FileCheck -check-prefix=x86_64 %s
; RUN: opt < %s -passes=rel-lookup-table-converter -relocation-model=pic -mtriple=aarch64 -S | FileCheck -check-prefix=aarch64 %s

@a0 = private unnamed_addr constant i32 0
@a1 = private unnamed_addr constant i32 1
@a2 = private unnamed_addr constant i32 2
@load_relative_1.table = private unnamed_addr constant [3 x ptr] [ptr @a0, ptr @a1, ptr @a2]

@x0 = internal unnamed_addr constant i64 0
@x1 = internal unnamed_addr constant i64 1
@x2 = internal unnamed_addr constant i64 2
@x3 = internal unnamed_addr constant i64 3
@y0 = internal unnamed_addr constant ptr @x3
@y1 = internal unnamed_addr constant ptr @x2
@y2 = internal unnamed_addr constant ptr @x1
@y3 = internal unnamed_addr constant ptr @x0
@load_relative_2.table = private unnamed_addr constant [4 x ptr] [ptr @y3, ptr @y2, ptr @y1, ptr @y0]

;.
; x86_64: @a0 = private constant i32 0
; x86_64: @a1 = private constant i32 1
; x86_64: @a2 = private constant i32 2
; x86_64: @load_relative_1.table.rel = private unnamed_addr constant [3 x i32] [i32 trunc (i64 sub (i64 ptrtoint (ptr @a0 to i64), i64 ptrtoint (ptr @load_relative_1.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @a1 to i64), i64 ptrtoint (ptr @load_relative_1.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @a2 to i64), i64 ptrtoint (ptr @load_relative_1.table.rel to i64)) to i32)], align 4
; x86_64: @x0 = internal unnamed_addr constant i64 0
; x86_64: @x1 = internal unnamed_addr constant i64 1
; x86_64: @x2 = internal unnamed_addr constant i64 2
; x86_64: @x3 = internal unnamed_addr constant i64 3
; x86_64: @y0 = internal constant ptr @x3
; x86_64: @y1 = internal constant ptr @x2
; x86_64: @y2 = internal constant ptr @x1
; x86_64: @y3 = internal constant ptr @x0
; x86_64: @load_relative_2.table.rel = private unnamed_addr constant [4 x i32] [i32 trunc (i64 sub (i64 ptrtoint (ptr @y3 to i64), i64 ptrtoint (ptr @load_relative_2.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @y2 to i64), i64 ptrtoint (ptr @load_relative_2.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @y1 to i64), i64 ptrtoint (ptr @load_relative_2.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @y0 to i64), i64 ptrtoint (ptr @load_relative_2.table.rel to i64)) to i32)], align 4
;.
; aarch64: @a0 = private constant i32 0
; aarch64: @a1 = private constant i32 1
; aarch64: @a2 = private constant i32 2
; aarch64: @load_relative_1.table.rel = private unnamed_addr constant [3 x i32] [i32 trunc (i64 sub (i64 ptrtoint (ptr @a0 to i64), i64 ptrtoint (ptr @load_relative_1.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @a1 to i64), i64 ptrtoint (ptr @load_relative_1.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @a2 to i64), i64 ptrtoint (ptr @load_relative_1.table.rel to i64)) to i32)], align 4
; aarch64: @x0 = internal unnamed_addr constant i64 0
; aarch64: @x1 = internal unnamed_addr constant i64 1
; aarch64: @x2 = internal unnamed_addr constant i64 2
; aarch64: @x3 = internal unnamed_addr constant i64 3
; aarch64: @y0 = internal constant ptr @x3
; aarch64: @y1 = internal constant ptr @x2
; aarch64: @y2 = internal constant ptr @x1
; aarch64: @y3 = internal constant ptr @x0
; aarch64: @load_relative_2.table.rel = private unnamed_addr constant [4 x i32] [i32 trunc (i64 sub (i64 ptrtoint (ptr @y3 to i64), i64 ptrtoint (ptr @load_relative_2.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @y2 to i64), i64 ptrtoint (ptr @load_relative_2.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @y1 to i64), i64 ptrtoint (ptr @load_relative_2.table.rel to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @y0 to i64), i64 ptrtoint (ptr @load_relative_2.table.rel to i64)) to i32)], align 4
;.
define ptr @load_relative_1(i64 %offset) {
; x86_64-LABEL: define ptr @load_relative_1(
; x86_64-SAME: i64 [[OFFSET:%.*]]) {
; x86_64-NEXT: [[RELTABLE_SHIFT:%.*]] = shl i64 [[OFFSET]], 2
; x86_64-NEXT: [[RELTABLE_INTRINSIC:%.*]] = call ptr @llvm.load.relative.i64(ptr @load_relative_1.table.rel, i64 [[RELTABLE_SHIFT]])
; x86_64-NEXT: ret ptr [[RELTABLE_INTRINSIC]]
;
; aarch64-LABEL: define ptr @load_relative_1(
; aarch64-SAME: i64 [[OFFSET:%.*]]) {
; aarch64-NEXT: [[RELTABLE_SHIFT:%.*]] = shl i64 [[OFFSET]], 2
; aarch64-NEXT: [[RELTABLE_INTRINSIC:%.*]] = call ptr @llvm.load.relative.i64(ptr @load_relative_1.table.rel, i64 [[RELTABLE_SHIFT]])
; aarch64-NEXT: ret ptr [[RELTABLE_INTRINSIC]]
;
%gep = getelementptr inbounds [3 x ptr], ptr @load_relative_1.table, i64 0, i64 %offset
%load = load ptr, ptr %gep
ret ptr %load
}

define ptr @load_relative_2(i64 %offset) {
; x86_64-LABEL: define ptr @load_relative_2(
; x86_64-SAME: i64 [[OFFSET:%.*]]) {
; x86_64-NEXT: [[RELTABLE_SHIFT:%.*]] = shl i64 [[OFFSET]], 2
; x86_64-NEXT: [[RELTABLE_INTRINSIC:%.*]] = call ptr @llvm.load.relative.i64(ptr @load_relative_2.table.rel, i64 [[RELTABLE_SHIFT]])
; x86_64-NEXT: ret ptr [[RELTABLE_INTRINSIC]]
;
; aarch64-LABEL: define ptr @load_relative_2(
; aarch64-SAME: i64 [[OFFSET:%.*]]) {
; aarch64-NEXT: [[RELTABLE_SHIFT:%.*]] = shl i64 [[OFFSET]], 2
; aarch64-NEXT: [[RELTABLE_INTRINSIC:%.*]] = call ptr @llvm.load.relative.i64(ptr @load_relative_2.table.rel, i64 [[RELTABLE_SHIFT]])
; aarch64-NEXT: ret ptr [[RELTABLE_INTRINSIC]]
;
%gep = getelementptr inbounds [4 x ptr], ptr @load_relative_2.table, i64 0, i64 %offset
%load = load ptr, ptr %gep
ret ptr %load
}
;.
; x86_64: attributes #[[ATTR0:[0-9]+]] = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
;.
; aarch64: attributes #[[ATTR0:[0-9]+]] = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
;.
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