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Diffstat (limited to 'lib/Target/ARM/README.txt')
| -rw-r--r-- | lib/Target/ARM/README.txt | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/lib/Target/ARM/README.txt b/lib/Target/ARM/README.txt index 11c48ad..a6f26a5 100644 --- a/lib/Target/ARM/README.txt +++ b/lib/Target/ARM/README.txt @@ -596,3 +596,12 @@ Make use of the "rbit" instruction. Take a look at test/CodeGen/Thumb2/machine-licm.ll. ARM should be taught how to licm and cse the unnecessary load from cp#1. + +//===---------------------------------------------------------------------===// + +The CMN instruction sets the flags like an ADD instruction, while CMP sets +them like a subtract. Therefore to be able to use CMN for comparisons other +than the Z bit, we'll need additional logic to reverse the conditionals +associated with the comparison. Perhaps a pseudo-instruction for the comparison, +with a post-codegen pass to clean up and handle the condition codes? +See PR5694 for testcase. |
