[llvm] r216934 - Add note to documentation about machine node chains.
Matthew.Arsenault at amd.com
Tue Sep 2 12:18:53 PDT 2014
Date: Tue Sep 2 14:18:52 2014
New Revision: 216934
Add note to documentation about machine node chains.
I've been assuming chain operands were always the first operand,
since the documentation says this. I was confused about why they
were missing after instruction selection. Apparently the convention
changes to using the last operand for MachineSDNodes and I've never
--- llvm/trunk/docs/CodeGenerator.rst (original)
+++ llvm/trunk/docs/CodeGenerator.rst Tue Sep 2 14:18:52 2014
@@ -769,7 +769,9 @@ provide an ordering between nodes that h
calls, returns, etc). All nodes that have side effects should take a token
chain as input and produce a new one as output. By convention, token chain
inputs are always operand #0, and chain results are always the last value
-produced by an operation.
+produced by an operation. However, after instruction selection, the
+machine nodes have their chain after the instruction's operands, and
+may be followed by glue nodes.
A SelectionDAG has designated "Entry" and "Root" nodes. The Entry node is
always a marker node with an Opcode of ``ISD::EntryToken``. The Root node is
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