llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-02-15 09:33:39 +00:00

History

Jakob Stoklund Olesen 07a267faec Set sub-register <undef> flags more accurately.

When widening an existing <def,reads-undef> operand to a super-register,
it may be necessary to clear the <undef> flag because the wider register
is now read-modify-write through the instruction.

Conversely, it may be necessary to add an <undef> flag when the
coalescer turns a full-register def into a sub-register def, but the
larger register wasn't live before the instruction.

This happens in test/CodeGen/ARM/coalesce-subregs.ll, but the test
is too small for the <undef> flags to affect the generated code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156951 91177308-0d34-0410-b5e6-96231b3b80d8

2012-05-16 21:22:35 +00:00

Analysis

reuse the result of some expensive computations in getSignExtendExpr() and getZeroExtendExpr()

2012-05-15 20:20:14 +00:00