60433c63ac
This function has a bug which will incorrectly reschedule instructions
after an INLINEASM_BR (which can branch). (The bug may also allow
scheduling past a throwing-CALL, I'm not certain.)
I could fix that bug, but, as the removed FIXME notes, it's better to
attempt rescheduling before converting to 3-addr form, as that may
remove the need to convert in the first place. In fact, the code to do
such reordering was added to this pass only a few months later, in
2011, via the addition of the function rescheduleMIBelowKill. That
code does not contain the same bug.
The removal of the sink3AddrInstruction function is not a no-op: in
some cases it would move an instruction post-conversion, when
rescheduleMIBelowKill would not move the instruction pre-converison.
However, this does not appear to be important: the machine instruction
scheduler can reorder the after-conversion instructions, in any case.
This patch fixes a kernel panic 4.4 LTS x86_64 Linux kernels, when
built with clang after 4b0aa5724f.
Link: https://github.com/ClangBuiltLinux/linux/issues/1085
Differential Revision: https://reviews.llvm.org/D83708
36 lines
1.1 KiB
LLVM
36 lines
1.1 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
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;; Verify that the machine instructions generated from the first
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;; getelementptr don't get sunk below the callbr. (Reduced from a bug
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;; report.)
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%struct1 = type { i8*, i32 }
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define void @klist_dec_and_del(%struct1*) {
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; CHECK-LABEL: klist_dec_and_del:
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; CHECK: # %bb.0:
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; CHECK-NEXT: leaq 8(%rdi), %rax
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; CHECK-NEXT: #APP
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; CHECK-NEXT: # 8(%rdi) .Ltmp0
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; CHECK-NEXT: #NO_APP
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; CHECK-NEXT: # %bb.2:
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; CHECK-NEXT: retq
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; CHECK-NEXT: .Ltmp0: # Block address taken
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; CHECK-NEXT: .LBB0_1:
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; CHECK-NEXT: movq $0, -8(%rax)
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; CHECK-NEXT: retq
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%2 = getelementptr inbounds %struct1, %struct1* %0, i64 0, i32 1
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callbr void asm sideeffect "# $0 $1", "*m,X,~{memory},~{dirflag},~{fpsr},~{flags}"(i32* %2, i8* blockaddress(@klist_dec_and_del, %3))
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to label %6 [label %3]
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3:
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%4 = getelementptr i32, i32* %2, i64 -2
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%5 = bitcast i32* %4 to i8**
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store i8* null, i8** %5, align 8
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br label %6
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6:
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ret void
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}
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