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| author | Bill Wendling <isanbard@gmail.com> | 2012-02-29 01:46:50 +0000 |
|---|---|---|
| committer | Bill Wendling <isanbard@gmail.com> | 2012-02-29 01:46:50 +0000 |
| commit | f2c78f344e56b4571072560ca07cf7dbe88654c9 (patch) | |
| tree | 5449c9f7ec66e833bec3714895a7335833617f94 /llvm/lib/Object/COFFObjectFile.cpp | |
| parent | 9e821456a354807c098cdea25b649c2b02dfa1ba (diff) | |
| download | bcm5719-llvm-f2c78f344e56b4571072560ca07cf7dbe88654c9.tar.gz bcm5719-llvm-f2c78f344e56b4571072560ca07cf7dbe88654c9.zip | |
Restrict this transformation to equality conditions.
This transformation is not correct for not-equal conditions:
(trunc x) != C1 & (and x, CA) != C2 -> (and x, CA|CMAX) != C1|C2
Let
C1 == 0
C2 == 0
CA == 0xFF0000
CMAX == 0xFF
and truncating to i8.
The original truth table:
x | A: trunc x != 0 | B: x & 0xFF0000 != 0 | A & B != 0
--------------------------------------------------------------
0x00000 | 0 | 0 | 0
0x00001 | 1 | 0 | 0
0x10000 | 0 | 1 | 0
0x10001 | 1 | 1 | 1
The truth table of the replacement:
x | x & 0xFF00FF != 0
----------------------------
0x00000 | 0
0x00001 | 1
0x10000 | 1
0x10001 | 1
So they are different.
llvm-svn: 151691
Diffstat (limited to 'llvm/lib/Object/COFFObjectFile.cpp')
0 files changed, 0 insertions, 0 deletions
