d10110a8a6
When GCC added support for stack smashing protections, it was defined that: > This hook returns a CALL_EXPR that alerts the runtime that the stack > protect guard variable has been modified. This expression should > involve a call to a noreturn function. > The default version of this hook invokes a function called > ‘__stack_chk_fail’, taking no arguments. Do so as well for __stack_smash_handler for OpenBSD. Every libc implementation I could find has __stack_chk_fail marked noreturn, or the implementation calls abort, exit, or panic (which themselves are noreturn). Glibc: https://sourceware.org/git/?p=glibc.git;a=blob;f=debug/stack_chk_fail.c Musl: https://git.musl-libc.org/cgit/musl/tree/src/env/__stack_chk_fail.c Bionic: https://android.googlesource.com/platform/bionic/+/refs/heads/master/libc/bionic/__stack_chk_fail.cpp FreeBSD: https://cgit.freebsd.org/src/tree/lib/libc/secure/stack_protector.c OpenBSD: https://github.com/openbsd/src/blob/master/lib/libc/sys/stack_protector.c NetBSD: https://github.com/NetBSD/src/blob/trunk/lib/libc/misc/stack_protector.c Linux Kernel: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/panic.c Apple: https://opensource.apple.com/source/Libc/Libc-1439.40.11/sys/OpenBSD/stack_protector.c.auto.html Link: https://gcc.gnu.org/onlinedocs/gccint/Stack-Smashing-Protection.html#Stack-Smashing-Protection This will later help us diagnose functions that fall through to other functions vs end in calls to functions that are noreturn. Reviewed By: efriedma Differential Revision: https://reviews.llvm.org/D146339
50 lines
2.3 KiB
LLVM
50 lines
2.3 KiB
LLVM
; RUN: llc -mtriple=x86_64-apple-darwin -print-after=finalize-isel -enable-selectiondag-sp=true %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=DARWIN-SELDAG
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; RUN: llc -mtriple=x86_64-apple-darwin -print-after=finalize-isel -enable-selectiondag-sp=false %s -o /dev/null 2>&1 | FileCheck %s --check-prefix=DARWIN-IR
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; RUN: llc -mtriple=i386-pc-windows-msvc -print-after=finalize-isel -enable-selectiondag-sp=true %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=MSVC-SELDAG
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; RUN: llc -mtriple=i386-pc-windows-msvc -print-after=finalize-isel -enable-selectiondag-sp=false %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=MSVC-IR
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; DARWIN-SELDAG: # Machine code for function test_branch_weights:
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; DARWIN-SELDAG: successors: %bb.[[SUCCESS:[0-9]+]](0x7ffff800), %bb.[[FAILURE:[0-9]+]]
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; DARWIN-SELDAG: bb.[[FAILURE]]{{[0-9a-zA-Z_.]+}}:
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; DARWIN-SELDAG: CALL64pcrel32 &__stack_chk_fail
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; DARWIN-SELDAG: bb.[[SUCCESS]]{{[0-9a-zA-Z_.]+}}:
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; DARWIN-IR: # Machine code for function test_branch_weights:
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; DARWIN-IR: successors: %bb.[[SUCCESS:[0-9]+]](0x7ffff800), %bb.[[FAILURE:[0-9]+]]
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; DARWIN-IR: bb.[[SUCCESS]]{{[0-9a-zA-Z_.]+}}:
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; DARWIN-IR: bb.[[FAILURE]]{{[0-9a-zA-Z_.]+}}:
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; DARWIN-IR: CALL64pcrel32 @__stack_chk_fail
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; MSVC-SELDAG: # Machine code for function test_branch_weights:
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; MSVC-SELDAG: :: (volatile load (s32) from @__security_cookie)
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; MSVC-SELDAG: (store (s32) into stack)
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; MSVC-SELDAG: (volatile load (s32) from %stack.0.StackGuardSlot)
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; MSVC-SELDAG: CALLpcrel32 @__security_check_cookie
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; MSVC always uses selection DAG now.
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; MSVC-IR: # Machine code for function test_branch_weights:
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; MSVC-IR: :: (volatile load (s32) from @__security_cookie)
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; MSVC-IR: (store (s32) into stack)
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; MSVC-IR: (volatile load (s32) from %stack.0.StackGuardSlot)
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; MSVC-IR: CALLpcrel32 @__security_check_cookie
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define i32 @test_branch_weights(i32 %n) #0 {
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entry:
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%a = alloca [128 x i32], align 16
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call void @llvm.lifetime.start.p0(i64 512, ptr %a)
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call void @foo2(ptr %a)
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%idxprom = sext i32 %n to i64
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%arrayidx = getelementptr inbounds [128 x i32], ptr %a, i64 0, i64 %idxprom
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%0 = load i32, ptr %arrayidx, align 4
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call void @llvm.lifetime.end.p0(i64 512, ptr %a)
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ret i32 %0
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}
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declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
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declare void @foo2(ptr)
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declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
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attributes #0 = { sspstrong "stack-protector-buffer-size"="8" }
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