[MIR] Update MIRLangRef with documentation on bundled instructions

Differential Revision: https://reviews.llvm.org/D41872

llvm-svn: 322198

1 files changed, 15 insertions, 1 deletions

diff --git a/llvm/docs/MIRLangRef.rst b/llvm/docs/MIRLangRef.rst
index 84bd6021f29..17f64e88b07 100644
--- a/llvm/docs/MIRLangRef.rst
+++ b/llvm/docs/MIRLangRef.rst
@@ -378,6 +378,21 @@ instruction's name:
 
 .. _registers:
 
+Bundled Instructions
+^^^^^^^^^^^^^^^^^^^^
+
+The syntax for bundled instructions is the following:
+
+.. code-block:: text
+
+    BUNDLE implicit-def %r0, implicit-def %r1, implicit %r2 {
+      %r0 = SOME_OP %r2
+      %r1 = ANOTHER_OP internal %r0
+    }
+
+The first instruction is often a bundle header. The instructions between ``{``
+and ``}`` are bundled with the first instruction.
+
 Registers
 ---------
 
@@ -743,7 +758,6 @@ For an int eq predicate ``ICMP_EQ``, the syntax is:
 
 .. TODO: Describe the parsers default behaviour when optional YAML attributes
    are missing.
-.. TODO: Describe the syntax for the bundled instructions.
 .. TODO: Describe the syntax for virtual register YAML definitions.
 .. TODO: Describe the machine function's YAML flag attributes.
 .. TODO: Describe the syntax for the register mask machine operands.