e018cbf720
There are two motivations. `-fno-pic -fstack-protector -mstack-protector-guard=global` created `__stack_chk_guard` is referenced directly on all ELF OSes except FreeBSD. This patch allows referencing the symbol indirectly with -fno-direct-access-external-data. Some Linux kernel folks want `-fno-pic -fstack-protector -mstack-protector-guard-reg=gs -mstack-protector-guard-symbol=__stack_chk_guard` created `__stack_chk_guard` to be referenced directly, avoiding R_X86_64_REX_GOTPCRELX (even if the relocation may be optimized out by the linker). https://github.com/llvm/llvm-project/issues/60116 Why they need this isn't so clear to me. --- Add module flag "direct-access-external-data" and set the dso_local property of the stack protector symbol. The module flag can benefit other LLVMCodeGen synthesized symbols that are not represented in LLVM IR. Nowadays, with `-fno-pic` being uncommon, ideally we should set "direct-access-external-data" when it is true. However, doing so would require ~90 clang/test tests to be updated, which are too much. As a compromise, we set "direct-access-external-data" only when it's different from the implied default value. Reviewed By: nickdesaulniers Differential Revision: https://reviews.llvm.org/D150841
34 lines
1.8 KiB
LLVM
34 lines
1.8 KiB
LLVM
; RUN: llc -filetype=obj -relocation-model=pic --verify-machineinstrs -print-after=postrapseudos < %s 2>&1 | FileCheck -check-prefix=CHECK-POST-RA %s
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; RUN: llc -filetype=obj -relocation-model=pic --verify-machineinstrs -print-after=arm-pseudo < %s 2>&1 | FileCheck -check-prefix=CHECK-POST-AP %s
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; CHECK-POST-RA: $r12 = t2LDRLIT_ga_pcrel target-flags(arm-got) @__stack_chk_guard
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; CHECK-POST-AP: $r12 = t2LDRpci %const.0, 14, $noreg
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target triple = "thumbv7-unknown-linux-android23"
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%"class.v8::internal::Assembler" = type {}
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%"class.v8::internal::Operand" = type { %"class.v8::internal::Register", %"class.v8::internal::Register", i32, i32, %"union.v8::internal::Operand::Value" }
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%"class.v8::internal::Register" = type {}
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%"union.v8::internal::Operand::Value" = type { i32, [20 x i8] }
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%"class.v8::internal::wasm::LiftoffAssembler" = type {}
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declare void @_ZN2v88internal9Assembler3addENS0_8RegisterES2_RKNS0_7OperandENS0_4SBitENS0_9ConditionE(ptr, [1 x i32], [1 x i32], ptr, i32, i32)
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; Function Attrs: ssp
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define void @_ZN2v88internal4wasm16LiftoffAssembler13emit_i32_addiENS0_8RegisterES3_i(ptr %0, [1 x i32] %1, [1 x i32] %2, i32 %3) #0 {
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%5 = alloca %"class.v8::internal::Operand", align 8
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%6 = getelementptr %"class.v8::internal::Operand", ptr %5
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%7 = getelementptr %"class.v8::internal::Operand", ptr %5
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%8 = getelementptr %"class.v8::internal::Operand", ptr %5
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%9 = getelementptr %"class.v8::internal::Operand", ptr %5
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%10 = getelementptr %"class.v8::internal::Operand", ptr %5, i32 0, i32 4, i32 0
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store i32 %3, ptr %10, align 4
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call void @_ZN2v88internal9Assembler3addENS0_8RegisterES2_RKNS0_7OperandENS0_4SBitENS0_9ConditionE(ptr %0, [1 x i32] %1, [1 x i32] %2, ptr %5, i32 0, i32 2)
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ret void
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}
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attributes #0 = { ssp }
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!llvm.module.flags = !{!0}
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!0 = !{i32 7, !"PIC Level", i32 2}
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