maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/test/CodeGen/X86/icall-branch-funnel.ll

172 lines
4.7 KiB
LLVM
Raw Normal View History

[X86] Enable the MachineVerifier by default The machine verifier was disabled for x86 by default. There are now only 9 tests failing, compared to what previously was between 20 and 30. This is a good opportunity to file bugs for all the remaining issues, then explicitly disable the failing tests and enabling the machine verifier by default. This allows us to avoid adding new tests that break the verifier. PR27481 llvm-svn: 345513
2018-10-30 00:57:43 +08:00
; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
; RUN: llc -mtriple=x86_64-unknown-linux -verify-machineinstrs=0 < %s | FileCheck %s
Use branch funnels for virtual calls when retpoline mitigation is enabled. The retpoline mitigation for variant 2 of CVE-2017-5715 inhibits the branch predictor, and as a result it can lead to a measurable loss of performance. We can reduce the performance impact of retpolined virtual calls by replacing them with a special construct known as a branch funnel, which is an instruction sequence that implements virtual calls to a set of known targets using a binary tree of direct branches. This allows the processor to speculately execute valid implementations of the virtual function without allowing for speculative execution of of calls to arbitrary addresses. This patch extends the whole-program devirtualization pass to replace certain virtual calls with calls to branch funnels, which are represented using a new llvm.icall.jumptable intrinsic. It also extends the LowerTypeTests pass to recognize the new intrinsic, generate code for the branch funnels (x86_64 only for now) and lay out virtual tables as required for each branch funnel. The implementation supports full LTO as well as ThinLTO, and extends the ThinLTO summary format used for whole-program devirtualization to support branch funnels. For more details see RFC: http://lists.llvm.org/pipermail/llvm-dev/2018-January/120672.html Differential Revision: https://reviews.llvm.org/D42453 llvm-svn: 327163
2018-03-10 03:11:44 +08:00
@g = external global i8
declare void @f0()
declare void @f1()
declare void @f2()
declare void @f3()
declare void @f4()
declare void @f5()
declare void @f6()
declare void @f7()
declare void @f8()
declare void @f9()
declare void @llvm.icall.branch.funnel(...)
define void @jt2(i8* nest, ...) {
; CHECK: jt2:
; CHECK: leaq g+1(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB0_1
; CHECK-NEXT: #
; CHECK-NEXT: jmp f0
; CHECK-NEXT: .LBB0_1:
; CHECK-NEXT: jmp f1
musttail call void (...) @llvm.icall.branch.funnel(
i8* %0,
i8* getelementptr (i8, i8* @g, i64 0), void ()* @f0,
i8* getelementptr (i8, i8* @g, i64 1), void ()* @f1,
...
)
ret void
}
define void @jt3(i8* nest, ...) {
; CHECK: jt3:
; CHECK: leaq g+1(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB1_1
; CHECK-NEXT: #
; CHECK-NEXT: jmp f0
; CHECK-NEXT: .LBB1_1:
; CHECK-NEXT: jne .LBB1_2
; CHECK-NEXT: #
; CHECK-NEXT: jmp f1
; CHECK-NEXT: .LBB1_2:
; CHECK-NEXT: jmp f2
musttail call void (...) @llvm.icall.branch.funnel(
i8* %0,
i8* getelementptr (i8, i8* @g, i64 0), void ()* @f0,
i8* getelementptr (i8, i8* @g, i64 2), void ()* @f2,
i8* getelementptr (i8, i8* @g, i64 1), void ()* @f1,
...
)
ret void
}
define void @jt7(i8* nest, ...) {
; CHECK: jt7:
; CHECK: leaq g+3(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB2_1
; CHECK-NEXT: #
; CHECK-NEXT: leaq g+1(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB2_6
; CHECK-NEXT: #
; CHECK-NEXT: jmp f0
; CHECK-NEXT: .LBB2_1:
; CHECK-NEXT: jne .LBB2_2
; CHECK-NEXT: #
; CHECK-NEXT: jmp f3
; CHECK-NEXT: .LBB2_6:
; CHECK-NEXT: jne .LBB2_7
; CHECK-NEXT: #
; CHECK-NEXT: jmp f1
; CHECK-NEXT: .LBB2_2:
; CHECK-NEXT: leaq g+5(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB2_3
; CHECK-NEXT: #
; CHECK-NEXT: jmp f4
; CHECK-NEXT: .LBB2_7:
; CHECK-NEXT: jmp f2
; CHECK-NEXT: .LBB2_3:
; CHECK-NEXT: jne .LBB2_4
; CHECK-NEXT: #
; CHECK-NEXT: jmp f5
; CHECK-NEXT: .LBB2_4:
; CHECK-NEXT: jmp f6
musttail call void (...) @llvm.icall.branch.funnel(
i8* %0,
i8* getelementptr (i8, i8* @g, i64 0), void ()* @f0,
i8* getelementptr (i8, i8* @g, i64 1), void ()* @f1,
i8* getelementptr (i8, i8* @g, i64 2), void ()* @f2,
i8* getelementptr (i8, i8* @g, i64 3), void ()* @f3,
i8* getelementptr (i8, i8* @g, i64 4), void ()* @f4,
i8* getelementptr (i8, i8* @g, i64 5), void ()* @f5,
i8* getelementptr (i8, i8* @g, i64 6), void ()* @f6,
...
)
ret void
}
define void @jt10(i8* nest, ...) {
; CHECK: jt10:
; CHECK: leaq g+5(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB3_1
; CHECK-NEXT: #
; CHECK-NEXT: leaq g+1(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB3_7
; CHECK-NEXT: #
; CHECK-NEXT: jmp f0
; CHECK-NEXT: .LBB3_1:
; CHECK-NEXT: jne .LBB3_2
; CHECK-NEXT: #
; CHECK-NEXT: jmp f5
; CHECK-NEXT: .LBB3_7:
; CHECK-NEXT: jne .LBB3_8
; CHECK-NEXT: #
; CHECK-NEXT: jmp f1
; CHECK-NEXT: .LBB3_2:
; CHECK-NEXT: leaq g+7(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB3_3
; CHECK-NEXT: #
; CHECK-NEXT: jmp f6
; CHECK-NEXT: .LBB3_8:
; CHECK-NEXT: leaq g+3(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB3_9
; CHECK-NEXT: #
; CHECK-NEXT: jmp f2
; CHECK-NEXT: .LBB3_3:
; CHECK-NEXT: jne .LBB3_4
; CHECK-NEXT: #
; CHECK-NEXT: jmp f7
; CHECK-NEXT: .LBB3_9:
; CHECK-NEXT: jne .LBB3_10
; CHECK-NEXT: #
; CHECK-NEXT: jmp f3
; CHECK-NEXT: .LBB3_4:
; CHECK-NEXT: leaq g+9(%rip), %r11
; CHECK-NEXT: cmpq %r11, %r10
; CHECK-NEXT: jae .LBB3_5
; CHECK-NEXT: #
; CHECK-NEXT: jmp f8
; CHECK-NEXT: .LBB3_10:
; CHECK-NEXT: jmp f4
; CHECK-NEXT: .LBB3_5:
; CHECK-NEXT: jmp f9
musttail call void (...) @llvm.icall.branch.funnel(
i8* %0,
i8* getelementptr (i8, i8* @g, i64 0), void ()* @f0,
i8* getelementptr (i8, i8* @g, i64 1), void ()* @f1,
i8* getelementptr (i8, i8* @g, i64 2), void ()* @f2,
i8* getelementptr (i8, i8* @g, i64 3), void ()* @f3,
i8* getelementptr (i8, i8* @g, i64 4), void ()* @f4,
i8* getelementptr (i8, i8* @g, i64 5), void ()* @f5,
i8* getelementptr (i8, i8* @g, i64 6), void ()* @f6,
i8* getelementptr (i8, i8* @g, i64 7), void ()* @f7,
i8* getelementptr (i8, i8* @g, i64 8), void ()* @f8,
i8* getelementptr (i8, i8* @g, i64 9), void ()* @f9,
...
)
ret void
}