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
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(
; 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: