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authorEvan Cheng <evan.cheng@apple.com>2007-02-08 06:04:54 +0000
committerEvan Cheng <evan.cheng@apple.com>2007-02-08 06:04:54 +0000
commitf50d09ad21dbb16e35460d63d23d331a2cac7a91 (patch)
treef1e80bbc2db213e6ed32bd1c0c9b29af9bbaca1c /docs/CommandGuide
parentf596a97287dc7c00486089162796dd66b627dadf (diff)
Fixed a long standing spiller bug that's exposed by Thumb:
The code sequence before the spiller is something like: = tMOVrr %reg1117 = tMOVrr %reg1078 = tLSLri %reg1117, 2 The it starts spilling: %r0 = tRestore <fi#5>, 0 %r1 = tRestore <fi#7>, 0 %r1 = tMOVrr %r1<kill> tSpill %r1, <fi#5>, 0 %reg1078 = tLSLri %reg1117, 2 It restores the value while processing the first tMOVrr. At this point, the spiller remembers fi#5 is available in %r0. Next it processes the second move. It restores the source before the move and spills the result afterwards. The move becomes a noop and is deleted. However, a spill has been inserted and that should invalidate reuse of %r0 for fi#5 and add reuse of %r1 for fi#5. Therefore, %reg1117 (which is also assigned fi#5) should get %r1, not %r0. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34039 91177308-0d34-0410-b5e6-96231b3b80d8
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