4f42e16516
If the pointer to be checked is statically known to be zero, the tag check will always pass since: 1) the tag is zero 2) shadow memory for address 0 is initialized to 0 and never updated. We can therefore elide the tag check. We perform the elision in two places: 1) the HWASan pass 2) when lowering the CHECK_MEMACCESS intrinsic. Conceivably, the HWASan pass may encounter a "cannot currently statically prove to be null" pointer (and is therefore unable to omit the intrinsic) that later optimization passes convert into a statically known-null pointer. As a last line of defense, we perform elision here too. This also updates the tests from https://github.com/llvm/llvm-project/pull/122186
68 lines
2.6 KiB
LLVM
68 lines
2.6 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
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; RUN: llc -filetype asm -o - %s | FileCheck %s
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; This shows that CodeGen for AArch64 will elide the tag check when lowering
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; the HWASan memaccess intrinsic for null pointers.
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;
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; N.B. The HWASan pass will normally omit the memaccess intrinsic if the
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; pointer is already statically known to be null.
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;
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; The source was generated from llvm/test/Instrumentation/HWAddressSanitizer/zero-ptr.ll
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; with the memaccess deliberately retained.
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; ModuleID = '<stdin>'
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source_filename = "<stdin>"
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target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
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target triple = "aarch64--linux-android10000"
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$hwasan.module_ctor = comdat any
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@__start_hwasan_globals = external hidden constant [0 x i8]
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@__stop_hwasan_globals = external hidden constant [0 x i8]
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@hwasan.note = private constant { i32, i32, i32, [8 x i8], i32, i32 } { i32 8, i32 8, i32 3, [8 x i8] c"LLVM\00\00\00\00", i32 trunc (i64 sub (i64 ptrtoint (ptr @__start_hwasan_globals to i64), i64 ptrtoint (ptr @hwasan.note to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @__stop_hwasan_globals to i64), i64 ptrtoint (ptr @hwasan.note to i64)) to i32) }, section ".note.hwasan.globals", comdat($hwasan.module_ctor), align 4
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; Function Attrs: sanitize_hwaddress
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define void @test_store_to_zeroptr() #0 {
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; CHECK-LABEL: test_store_to_zeroptr:
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; CHECK: // %bb.0: // %entry
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; CHECK-NEXT: str x30, [sp, #-16]! // 8-byte Folded Spill
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; CHECK-NEXT: .cfi_def_cfa_offset 16
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; CHECK-NEXT: .cfi_offset w30, -16
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; CHECK-NEXT: mov x8, xzr
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; CHECK-NEXT: mov w9, #42 // =0x2a
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; CHECK-NEXT: str x9, [x8]
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; CHECK-NEXT: ldr x30, [sp], #16 // 8-byte Folded Reload
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; CHECK-NEXT: ret
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entry:
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%.hwasan.shadow = call ptr asm "", "=r,0"(ptr null)
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%b = inttoptr i64 0 to ptr
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call void @llvm.hwasan.check.memaccess.shortgranules.fixedshadow(ptr %b, i32 19, i64 0)
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store i64 42, ptr %b, align 8
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ret void
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}
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; Function Attrs: nounwind
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declare void @llvm.hwasan.check.memaccess.shortgranules.fixedshadow(ptr, i32 immarg, i64 immarg) #1
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attributes #0 = { sanitize_hwaddress }
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attributes #1 = { nounwind }
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declare void @__hwasan_init()
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; Function Attrs: nounwind
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define internal void @hwasan.module_ctor() #1 comdat {
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; CHECK-LABEL: hwasan.module_ctor:
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; CHECK: // %bb.0:
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; CHECK-NEXT: str x30, [sp, #-16]! // 8-byte Folded Spill
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; CHECK-NEXT: bl __hwasan_init
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; CHECK-NEXT: ldr x30, [sp], #16 // 8-byte Folded Reload
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; CHECK-NEXT: ret
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call void @__hwasan_init()
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ret void
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}
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!llvm.module.flags = !{!1}
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!0 = !{ptr @hwasan.note}
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!1 = !{i32 4, !"nosanitize_hwaddress", i32 1}
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