afd20587f9
Fix https://github.com/llvm/llvm-project/issues/63579 ``` % cat a.c void foo() {} % clang --target=arm-none-eabi -mthumb -mno-unaligned-access -fsanitize=kcfi a.c -S -o - | grep p2align .p2align 1 % clang --target=armv6m-none-eabi -fsanitize=function a.c -S -o - | grep p2align .p2align 1 ``` Ensure that -fsanitize={function,kcfi} instrumented functions are aligned by at least 4, so that loading the type hash before the function label will not cause a misaligned access. This is especially important for -mno-unaligned-access configurations that don't set `setMinFunctionAlignment` to 4 or greater. With this patch, the generated assembly for the examples above will contain `.p2align 2` before the type hash. If `__attribute__((aligned(N)))` or `-falign-functions=N` is specified, the larger alignment will be used. Reviewed By: simon_tatham, samitolvanen Differential Revision: https://reviews.llvm.org/D154125
29 lines
733 B
LLVM
29 lines
733 B
LLVM
; RUN: llc -mtriple=thumbv6m-none-eabi < %s | FileCheck %s
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; CHECK-LABEL: .globl nosan
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; CHECK-NEXT: .p2align 1
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; CHECK-NEXT: .type nosan,%function
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; CHECK-NEXT: .code 16
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; CHECK-NEXT: .thumb_func
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; CHECK-NEXT: nosan:
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define dso_local void @nosan() nounwind {
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ret void
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}
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;; The alignment is at least 4 to avoid unaligned type hash loads when this
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;; instrumented function is indirectly called.
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; CHECK-LABEL: .globl f1
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; CHECK-NEXT: .p2align 2
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; CHECK-NEXT: .type f1,%function
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; CHECK-NEXT: .long 3170468932
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; CHECK-NEXT: .code 16
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; CHECK-NEXT: .thumb_func
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; CHECK-NEXT: f1:
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define void @f1(ptr noundef %x) !kcfi_type !1 {
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ret void
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}
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!llvm.module.flags = !{!0}
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!0 = !{i32 4, !"kcfi", i32 1}
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!1 = !{i32 -1124498364}
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