[llvm] r265944 - [SystemZ] README: remove an implemented idea, add some new ones

[Ulrich Weigand via llvm-commits]

Author: uweigand
Date: Mon Apr 11 09:38:47 2016
New Revision: 265944

URL: http://llvm.org/viewvc/llvm-project?rev=265944&view=rev
Log:
[SystemZ] README: remove an implemented idea, add some new ones

The note about conditional returns can now be removed, as they are
implemented. Let's also add 2 new ones in exchange.

Author: koriakin
Differential Revision: http://reviews.llvm.org/D18962


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=265944&r1=265943&r2=265944&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/README.txt (original)
+++ llvm/trunk/lib/Target/SystemZ/README.txt Mon Apr 11 09:38:47 2016
@@ -43,11 +43,6 @@ We don't use the BRANCH ON INDEX instruc
 
 --
 
-We might want to use BRANCH ON CONDITION for conditional indirect calls
-and conditional returns.
-
---
-
 We don't use the TEST DATA CLASS instructions.
 
 --
@@ -166,3 +161,16 @@ If needed, we can support 16-byte atomic
 
 We might want to model all access registers and use them to spill
 32-bit values.
+
+--
+
+We might want to use 'j .+2' as a trap instruction, like gcc does.  It can
+also be made conditional like the return instruction, allowing us to utilize
+compare-and-trap and load-and-trap instructions.
+
+--
+
+We might want to use the 'overflow' condition of eg. AR to support
+llvm.sadd.with.overflow.i32 and related instructions - the generated code
+for signed overflow check is currently quite bad.  This would improve
+the results of using -ftrapv.