Some new entries about truncate / anyext

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28548 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index e4a9b55c45..d944cbf103 100644
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -606,3 +606,19 @@ _bar:
 
 The current isel scheme will not allow the load to be folded in the call since
 the load's chain result is read by the callseq_start.
+
+//===---------------------------------------------------------------------===//
+
+Don't forget to find a way to squash noop truncates in the JIT environment.
+
+//===---------------------------------------------------------------------===//
+
+Implement anyext in the same manner as truncate that would allow them to be
+eliminated.
+
+//===---------------------------------------------------------------------===//
+
+How about implementing truncate / anyext as a property of machine instruction
+operand? i.e. Print as 32-bit super-class register / 16-bit sub-class register.
+Do this for the cases where a truncate / anyext is guaranteed to be eliminated.
+For IA32 that is truncate from 32 to 16 and anyext from 16 to 32.