[llvm] r188062 - [SystemZ] Update README
Richard Sandiford
rsandifo at linux.vnet.ibm.com
Fri Aug 9 02:25:57 PDT 2013
Author: rsandifo
Date: Fri Aug 9 04:25:57 2013
New Revision: 188062
URL: http://llvm.org/viewvc/llvm-project?rev=188062&view=rev
Log:
[SystemZ] Update README
Modified:
llvm/trunk/lib/Target/SystemZ/README.txt
Modified: llvm/trunk/lib/Target/SystemZ/README.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/README.txt?rev=188062&r1=188061&r2=188062&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/README.txt (original)
+++ llvm/trunk/lib/Target/SystemZ/README.txt Fri Aug 9 04:25:57 2013
@@ -47,7 +47,7 @@ There is no scheduling support.
--
-We don't use the BRANCH ON COUNT or BRANCH ON INDEX families of instruction.
+We don't use the BRANCH ON INDEX instructions.
--
@@ -56,18 +56,7 @@ and conditional returns.
--
-We don't use the condition code results of anything except comparisons.
-
-Implementing this may need something more finely grained than the z_cmp
-and z_ucmp that we have now. It might (or might not) also be useful to
-have a mask of "don't care" values in conditional branches. For example,
-integer comparisons never set CC to 3, so the bottom bit of the CC mask
-isn't particularly relevant. JNLH and JE are equally good for testing
-equality after an integer comparison, etc.
-
---
-
-We don't use the LOAD AND TEST or TEST DATA CLASS instructions.
+We don't use the TEST DATA CLASS instructions.
--
@@ -77,9 +66,10 @@ condition codes. For example, we could
--
-We don't optimize block memory operations.
+We don't optimize block memory operations, except using single MVCs
+for memcpy.
-It's definitely worth using things like MVC, CLC, NC, XC and OC with
+It's definitely worth using things like CLC, NC, XC and OC with
constant lengths. MVCIN may be worthwhile too.
We should probably implement things like memcpy using MVC with EXECUTE.
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