[PATCH] D77852: Outline CFI Instructions in Tail Calls

[Vedant Kumar via Phabricator via llvm-commits]

vsk added a comment.

Hi all,

I'm seeing what looks like an unexpected use of $noreg when I run some of these tests with synthetic debug uses inserted into the MIR stream (with -debugify-and-strip-all-safe). This is what I see:

  ~/src/builds/llvm-project-master-RA (1) $ ./bin/llc -debugify-and-strip-all-safe -mtriple=aarch64 -run-pass=machine-outliner -verify-machineinstrs /Users/vsk/src/llvm-project-master/llvm/test/CodeGen/AArch64/machine-outliner-side-effect.mir -o - > bad2.mir
  ~/src/builds/llvm-project-master-RA (0) $ ./bin/llc -debugify-and-strip-all-safe=0 -mtriple=aarch64 -run-pass=machine-outliner -verify-machineinstrs /Users/vsk/src/llvm-project-master/llvm/test/CodeGen/AArch64/machine-outliner-side-effect.mir -o - > good2.mir
  ~/src/builds/llvm-project-master-RA (0) $ diff -u {good,bad}2.mir
  --- good2.mir   2020-04-24 16:53:17.000000000 -0700
  +++ bad2.mir    2020-04-24 16:53:08.000000000 -0700
  @@ -62,11 +62,11 @@
     bb.0:
       liveins: $x0, $x20
  
  -    BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit $x20, implicit $sp
  +    BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit $noreg, implicit $sp, implicit $x20
       renamable $x21 = COPY $x0
  -    BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit $x20, implicit $sp
  +    BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit $noreg, implicit $sp, implicit $x20
       renamable $x22 = COPY $x0
  -    BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit $x20, implicit $sp
  +    BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit $noreg, implicit $sp, implicit $x20
       renamable $x3 = COPY $x0
       RET_ReallyLR

Not sure if that's something to worry about (or even whether this patch causes the difference), just thought I'd report the difference. Generally we don't expect tests to fail when -debugify-and-strip-all-safe is added, but there are exceptions of course.


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https://reviews.llvm.org/D77852