[PATCH] D126048: [SplitKit] Handle early clobber + tied to def correctly

[Matthias Braun via Phabricator via llvm-commits]

MatzeB added inline comments.


================
Comment at: llvm/lib/CodeGen/SplitKit.cpp:1376
+      // in [16e, 32d).
+      unsigned OpIdx = MI->findRegisterUseOperandIdx(MO.getReg());
+      unsigned DefOpIdx = MI->findTiedOperandIdx(OpIdx);
----------------
kito-cheng wrote:
> MatzeB wrote:
> > Use `getOperandNo` that's faster and avoids trouble if multiple operands use the same register.
> Seems like `getOperandNo` only work with iterator? and that is what we don't have here :(
> 
> Anyway I change to that, but it is because I hit a regression for a testcase from X86...so I just try to traverse all input operand see which operand is tied-def and using same register as MO here...
> 
> See CodeGen/X86/statepoint-invoke-ra.mir:
> ```
>   dead %40:gr64 = STATEPOINT 2882400000, 0, 1, target-flags(x86-plt) @quux, $edi, 2, 0, 2, 0, 2, 6, 1, 4, %stack.0, 0, 1, 4, %stack.1, 0, 1, 4, %stack.2, 0, 1, 4, %stack.3, 0, %40:gr64, 1, 4, %stack.4, 0, 2, 1, %40:gr64(tied-def 0), 2, 0, 2, 1, 0, 0, <regmask $bh $bl $bp $bph $bpl $bx $ebp $ebx $hbp $hbx $rbp $rbx $r12 $r13 $r14 $r15 $r12b $r13b $r14b $r15b $r12bh $r13bh $r14bh $r15bh $r12d $r13d $r14d $r15d $r12w $r13w $r14w $r15w $r12wh and 3 more...>, implicit-def $rsp, implicit-def $ssp :: (volatile load store (s32) on %stack.0), (volatile load store (s32) on %stack.1), (volatile load store (s32) on %stack.2), (volatile load store (s32) on %stack.3), (volatile load store (s32) on %stack.4)
> ```
> 
> %40 appeared 3 times in this instruction, one for def, and two for use, and only one def has `tied-def 0`.
Well it's defined as `using const_mop_iterator = const MachineOperand *;`, so you should be good passing in the pointer, there's a some other places in the code that do the same.


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  https://reviews.llvm.org/D126048/new/

https://reviews.llvm.org/D126048