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llvm-project/llvm/test/CodeGen/X86/icall-branch-funnel.ll

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[CodeGen] Make branch funnels pass the machine verifier We previously marked all the tests with branch funnels as `-verify-machineinstrs=0`. This is an attempt to fix it. 1) `ICALL_BRANCH_FUNNEL` has no defs. Mark it as `let OutOperandList = (outs)` 2) After that we hit an assert: ``` Assertion failed: (Op.getValueType() != MVT::Other && Op.getValueType() != MVT::Glue && "Chain and glue operands should occur at end of operand list!"), function AddOperand, file /Users/francisvm/llvm/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp, line 461. ``` The chain operand was added at the beginning of the operand list. Move that to the end. 3) After that we hit another verifier issue in the pseudo expansion where the registers used in the cmps and jmps are not added to the livein lists. Add the `EFLAGS` to all the new MBBs that we create. PR39436 Differential Review: https://reviews.llvm.org/D54155 llvm-svn: 365058
2019-07-04 01:16:45 +08:00
; RUN: llc -mtriple=x86_64-unknown-linux < %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
}