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| author | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2012-10-12 18:03:04 +0000 |
|---|---|---|
| committer | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2012-10-12 18:03:04 +0000 |
| commit | 795f951c6d5c60a10ffc8e0fdfa22b7c3b499f35 (patch) | |
| tree | 62bd5cb59ca7cba27eae9ba14cf44cee5eebfa2b /docs/BitCodeFormat.rst | |
| parent | 562892034651ee4e29c31d03e55e8b8576f56369 (diff) | |
Fix coalescing with IMPLICIT_DEF values.
PHIElimination inserts IMPLICIT_DEF instructions to guarantee that all
PHI predecessors have a live-out value. These IMPLICIT_DEF values are
not considered to be real interference when coalescing virtual
registers:
%vreg1 = IMPLICIT_DEF
%vreg2 = MOV32r0
When joining %vreg1 and %vreg2, the IMPLICIT_DEF instruction and its
value number should simply be erased since the %vreg2 value number now
provides a live-out value for the PHI predecesor block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165813 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/BitCodeFormat.rst')
0 files changed, 0 insertions, 0 deletions