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| author | Nick Desaulniers <ndesaulniers@google.com> | 2023-04-27 13:39:54 -0700 |
|---|---|---|
| committer | Tom Stellard <tstellar@redhat.com> | 2023-05-01 21:09:22 -0700 |
| commit | e861196707993f45503621cd8472e94ddd1d8c97 (patch) | |
| tree | c11d10c33a7bada985c082234abf3d8d1f737d5d | |
| parent | ec79a47304289d9e32022e5570fe6c7efa40c59b (diff) | |
| download | llvm-e861196707993f45503621cd8472e94ddd1d8c97.tar.gz | |
[CodeGen][MachineLastInstrsCleanup] fix INLINEASM_BR hazard
If the removable definition resides in an INLINEASM_BR target, the
reuseable candidate might not dominate the INLINEASM_BR.
bb0:
INLINEASM_BR &"" %bb.1
renamable $x8 = MOVi64imm 29273397577910035
B %bb.2
...
bb1:
renamable $x8 = MOVi64imm 29273397577910035
renamable $x8 = ADDXri killed renamable $x8, 2048, 0
bb2:
Removing the second mov is a hazard when the inline asm branches to bb1.
Skip such replacements when the to be removed instruction is in the
target of such an INLINEASM_BR instruction.
We could get more aggressive about this in the future, but for now
simply abort.
This is causing a boot failure on linux-4.19.y branches of the LTS Linux
kernel for ARCH=arm64 with CONFIG_RANDOMIZE_BASE=y (KASLR) and
CONFIG_UNMAP_KERNEL_AT_EL0=y (KPTI).
Link: https://reviews.llvm.org/D123394
Link: https://github.com/ClangBuiltLinux/linux/issues/1837
Thanks to @nathanchance for the report, and @ardb for debugging.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D149191
(cherry picked from commit 012ea747ed0275c499f69c82ac0f635f4c76f746)
| -rw-r--r-- | llvm/lib/CodeGen/MachineLateInstrsCleanup.cpp | 3 | ||||
| -rw-r--r-- | llvm/test/CodeGen/AArch64/machine-latecleanup-inlineasm.mir | 3 |
2 files changed, 4 insertions, 2 deletions
diff --git a/llvm/lib/CodeGen/MachineLateInstrsCleanup.cpp b/llvm/lib/CodeGen/MachineLateInstrsCleanup.cpp index c400ce190b46..bb33b843e024 100644 --- a/llvm/lib/CodeGen/MachineLateInstrsCleanup.cpp +++ b/llvm/lib/CodeGen/MachineLateInstrsCleanup.cpp @@ -175,7 +175,8 @@ bool MachineLateInstrsCleanup::processBlock(MachineBasicBlock *MBB) { Reg2DefMap &MBBDefs = RegDefs[MBB->getNumber()]; // Find reusable definitions in the predecessor(s). - if (!MBB->pred_empty() && !MBB->isEHPad()) { + if (!MBB->pred_empty() && !MBB->isEHPad() && + !MBB->isInlineAsmBrIndirectTarget()) { MachineBasicBlock *FirstPred = *MBB->pred_begin(); for (auto [Reg, DefMI] : RegDefs[FirstPred->getNumber()]) if (llvm::all_of( diff --git a/llvm/test/CodeGen/AArch64/machine-latecleanup-inlineasm.mir b/llvm/test/CodeGen/AArch64/machine-latecleanup-inlineasm.mir index af18e6de374a..f3538122505a 100644 --- a/llvm/test/CodeGen/AArch64/machine-latecleanup-inlineasm.mir +++ b/llvm/test/CodeGen/AArch64/machine-latecleanup-inlineasm.mir @@ -159,8 +159,9 @@ body: | ; CHECK-NEXT: {{ $}} ; CHECK-NEXT: bb.1.bb8 (machine-block-address-taken, inlineasm-br-indirect-target): ; CHECK-NEXT: successors: %bb.2(0x80000000) - ; CHECK-NEXT: liveins: $w20, $x19, $x21, $x22, $x23, $x24, $x8 + ; CHECK-NEXT: liveins: $w20, $x19, $x21, $x22, $x23, $x24 ; CHECK-NEXT: {{ $}} + ; CHECK-NEXT: renamable $x8 = MOVi64imm 29273397577910035 ; CHECK-NEXT: renamable $x8 = ADDXri killed renamable $x8, 2048, 0 ; CHECK-NEXT: {{ $}} ; CHECK-NEXT: bb.2.bb9: |