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LowerTypeTests: Set small code model on imported globals. #141324

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Merged
merged 4 commits into from
May 27, 2025
Merged

LowerTypeTests: Set small code model on imported globals. #141324

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[𝘀𝗽𝗿] changes to main this commit is based on
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[𝘀𝗽𝗿] initial version
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[𝘀𝗽𝗿] changes introduced through rebase
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18 changes: 16 additions & 2 deletions llvm/lib/Transforms/IPO/LowerTypeTests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1019,8 +1019,22 @@ LowerTypeTestsModule::importTypeId(StringRef TypeId) {
return C;
};

if (TIL.TheKind != TypeTestResolution::Unsat)
TIL.OffsetedGlobal = ImportGlobal("global_addr");
if (TIL.TheKind != TypeTestResolution::Unsat) {
auto *GV = ImportGlobal("global_addr");
// This is either a vtable (in .data.rel.ro) or a jump table (in .text).
// Either way it's expected to be in the low 2 GiB, so set the small code
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preferably there would be some reference why we would expect that

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Added comment with an explanation.

// model.
//
// For .data.rel.ro, we currently place all such sections in the low 2 GiB
// [1], and for .text the sections are expected to be in the low 2 GiB under
// the small and medium code models [2] and this pass only supports those
// code models (e.g. jump tables use jmp instead of movabs/jmp).
//
// [1]https://github.com/llvm/llvm-project/pull/137742
// [2]https://maskray.me/blog/2023-05-14-relocation-overflow-and-code-models
GV->setCodeModel(CodeModel::Small);
TIL.OffsetedGlobal = GV;
}

if (TIL.TheKind == TypeTestResolution::ByteArray ||
TIL.TheKind == TypeTestResolution::Inline ||
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14 changes: 7 additions & 7 deletions llvm/test/Transforms/LowerTypeTests/import.ll
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Expand Up @@ -6,29 +6,29 @@ target datalayout = "e-p:64:64"

declare i1 @llvm.type.test(ptr %ptr, metadata %bitset) nounwind readnone

; CHECK-DAG: @__typeid_single_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_inline6_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_single_global_addr = external hidden global [0 x i8], code_model "small"
; CHECK-DAG: @__typeid_inline6_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_inline6_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_inline6_size_m1 = external hidden global [0 x i8], !absolute_symbol !1
; X86-DAG: @__typeid_inline6_inline_bits = external hidden global [0 x i8], !absolute_symbol !2
; CHECK-DAG: @__typeid_inline5_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_inline5_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_inline5_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_inline5_size_m1 = external hidden global [0 x i8], !absolute_symbol !3
; X86-DAG: @__typeid_inline5_inline_bits = external hidden global [0 x i8], !absolute_symbol !4
; CHECK-DAG: @__typeid_bytearray32_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_bytearray32_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_bytearray32_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_bytearray32_size_m1 = external hidden global [0 x i8], !absolute_symbol !4
; CHECK-DAG: @__typeid_bytearray32_byte_array = external hidden global [0 x i8]
; X86-DAG: @__typeid_bytearray32_bit_mask = external hidden global [0 x i8], !absolute_symbol !0
; CHECK-DAG: @__typeid_bytearray7_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_bytearray7_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_bytearray7_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_bytearray7_size_m1 = external hidden global [0 x i8], !absolute_symbol !5
; CHECK-DAG: @__typeid_bytearray7_byte_array = external hidden global [0 x i8]
; X86-DAG: @__typeid_bytearray7_bit_mask = external hidden global [0 x i8], !absolute_symbol !0
; CHECK-DAG: @__typeid_allones32_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_allones32_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_allones32_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_allones32_size_m1 = external hidden global [0 x i8], !absolute_symbol !4
; CHECK-DAG: @__typeid_allones7_global_addr = external hidden global [0 x i8]
; CHECK-DAG: @__typeid_allones7_global_addr = external hidden global [0 x i8], code_model "small"
; X86-DAG: @__typeid_allones7_align = external hidden global [0 x i8], !absolute_symbol !0
; X86-DAG: @__typeid_allones7_size_m1 = external hidden global [0 x i8], !absolute_symbol !5

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