[PATCH] D100296: [Live Intervals] Teach Greedy RA to recognize special case live-through

Tue Apr 13 19:54:38 PDT 2021

skatkov added inline comments.

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Comment at: llvm/test/CodeGen/X86/statepoint-regs.ll:58
 ; CHECK:       ## %bb.0: ## %entry
-; CHECK-NEXT:    subq $24, %rsp
+; CHECK-NEXT:    pushq %rbp
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
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reames wrote:
> This test delta (and all the following analogous ones) is interesting.  It's correct, but it's a case where we'd have better off pushing the deopt operands onto the stack.  (Note: "push" here is key word.  General spilling and leaving other values in registers would be smaller code wise, but probably *not* faster due to stack engine.)
> 
> Probably a good case to look into for regalloc quality around deopt.  
I guess it is a case of better use spilling instead of first usage of callee saved register.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100296/new/

https://reviews.llvm.org/D100296