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
62 lines
3.6 KiB
LLVM
62 lines
3.6 KiB
LLVM
; RUN: rm -rf %t && split-file %s %t && cd %t
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; RUN: cat a.ll pic.ll > b.ll
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; RUN: llc < b.ll -mtriple=arm64-apple-ios -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=DARWIN
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; RUN: llc < b.ll -mtriple=arm64-apple-ios -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=DARWIN
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; RUN: llc < b.ll -mtriple=aarch64-linux-gnu -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC-LINUX
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; RUN: llc < a.ll -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=large -no-integrated-as | FileCheck %s -check-prefix=STATIC-LARGE
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; RUN: llc < a.ll -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=small -no-integrated-as | FileCheck %s -check-prefix=STATIC-SMALL
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; RUN: llc < b.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=arm64-apple-ios -relocation-model=pic -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=DARWIN,FALLBACK
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; RUN: llc < b.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=arm64-apple-ios -relocation-model=static -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=DARWIN,FALLBACK
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; RUN: llc < b.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=pic -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=PIC-LINUX,FALLBACK
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; RUN: llc < a.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=large -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=STATIC-LARGE,FALLBACK
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; RUN: llc < a.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=small -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=STATIC-SMALL,FALLBACK
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; DARWIN: foo2
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; DARWIN: adrp [[R0:x[0-9]+]], ___stack_chk_guard@GOTPAGE
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; DARWIN: ldr [[R1:x[0-9]+]], [[[R0]], ___stack_chk_guard@GOTPAGEOFF]
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; DARWIN: ldr {{x[0-9]+}}, [[[R1]]]
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; PIC-LINUX: foo2
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; PIC-LINUX: adrp [[R0:x[0-9]+]], :got:__stack_chk_guard
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; PIC-LINUX: ldr [[R1:x[0-9]+]], [[[R0]], :got_lo12:__stack_chk_guard]
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; PIC-LINUX: ldr {{x[0-9]+}}, [[[R1]]]
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; STATIC-LARGE: foo2
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; STATIC-LARGE: movz [[R0:x[0-9]+]], #:abs_g0_nc:__stack_chk_guard
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; STATIC-LARGE: movk [[R0]], #:abs_g1_nc:__stack_chk_guard
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; STATIC-LARGE: movk [[R0]], #:abs_g2_nc:__stack_chk_guard
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; STATIC-LARGE: movk [[R0]], #:abs_g3:__stack_chk_guard
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; STATIC-LARGE: ldr {{x[0-9]+}}, [[[R0]]]
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; STATIC-SMALL: foo2
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; STATIC-SMALL: adrp [[R0:x[0-9]+]], __stack_chk_guard
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; STATIC-SMALL: ldr {{x[0-9]+}}, [[[R0]], :lo12:__stack_chk_guard]
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; FALLBACK-NOT: remark:{{.*}}llvm.lifetime.end
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; FALLBACK-NOT: remark:{{.*}}llvm.lifetime.start
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;--- a.ll
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define i32 @test_stack_guard_remat() #0 {
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entry:
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%a1 = alloca [256 x i32], align 4
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call void @llvm.lifetime.start.p0(i64 1024, ptr %a1)
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call void @foo3(ptr %a1)
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call void asm sideeffect "foo2", "~{w0},~{w1},~{w2},~{w3},~{w4},~{w5},~{w6},~{w7},~{w8},~{w9},~{w10},~{w11},~{w12},~{w13},~{w14},~{w15},~{w16},~{w17},~{w18},~{w19},~{w20},~{w21},~{w22},~{w23},~{w24},~{w25},~{w26},~{w27},~{w28},~{w29},~{w30}"()
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call void @llvm.lifetime.end.p0(i64 1024, ptr %a1)
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ret i32 0
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}
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; Function Attrs: nounwind
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declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
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declare void @foo3(ptr)
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; Function Attrs: nounwind
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declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
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attributes #0 = { nounwind sspstrong "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
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;--- pic.ll
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!llvm.module.flags = !{!0}
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!0 = !{i32 8, !"PIC Level", i32 2}
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