MIR Serialization: Change MIR syntax - use custom syntax for MBBs.

This commit modifies the way the machine basic blocks are serialized - now the
machine basic blocks are serialized using a custom syntax instead of relying on
YAML primitives. Instead of using YAML mappings to represent the individual
machine basic blocks in a machine function's body, the new syntax uses a single
YAML block scalar which contains all of the machine basic blocks and
instructions for that function.

This is an example of a function's body that uses the old syntax:

    body:
      - id: 0
        name: entry
        instructions:
          - '%eax = MOV32r0 implicit-def %eflags'
          - 'RETQ %eax'
    ...

The same body is now written like this:

    body: |
      bb.0.entry:
        %eax = MOV32r0 implicit-def %eflags
        RETQ %eax
    ...

This syntax change is motivated by the fact that the bundled machine
instructions didn't map that well to the old syntax which was using a single
YAML sequence to store all of the machine instructions in a block. The bundled
machine instructions internally use flags like BundledPred and BundledSucc to
determine the bundles, and serializing them as MI flags using the old syntax
would have had a negative impact on the readability and the ease of editing
for MIR files. The new syntax allows me to serialize the bundled machine
instructions using a block construct without relying on the internal flags,
for example:

   BUNDLE implicit-def dead %itstate, implicit-def %s1 ... {
      t2IT 1, 24, implicit-def %itstate
      %s1 = VMOVS killed %s0, 1, killed %cpsr, implicit killed %itstate
   }

This commit also converts the MIR testcases to the new syntax. I developed
a script that can convert from the old syntax to the new one. I will post the
script on the llvm-commits mailing list in the thread for this commit.

llvm-svn: 244982

1 files changed, 12 insertions, 16 deletions

diff --git a/llvm/test/CodeGen/MIR/X86/unknown-named-machine-basic-block.mir b/llvm/test/CodeGen/MIR/X86/unknown-named-machine-basic-block.mir
index f304113f40b..6627273d447 100644
--- a/llvm/test/CodeGen/MIR/X86/unknown-named-machine-basic-block.mir
+++ b/llvm/test/CodeGen/MIR/X86/unknown-named-machine-basic-block.mir
@@ -20,20 +20,16 @@
 ...
 ---
 name:            foo
-body:
- - id:              0
-   name:            entry
-   instructions:
-     - '%eax = MOV32rm %rdi, 1, _, 0, _'
-     - 'CMP32ri8 %eax, 10, implicit-def %eflags'
-     # CHECK: [[@LINE+1]]:14: the name of machine basic block #2 isn't 'hit'
-     - 'JG_1 %bb.2.hit, implicit %eflags'
- - id:              1
-   name:            less
-   instructions:
-     - '%eax = MOV32r0 implicit-def %eflags'
- - id:              2
-   name:            exit
-   instructions:
-     - 'RETQ %eax'
+body: |
+  bb.0.entry:
+    %eax = MOV32rm %rdi, 1, _, 0, _
+    CMP32ri8 %eax, 10, implicit-def %eflags
+    ; CHECK: [[@LINE+1]]:10: the name of machine basic block #2 isn't 'hit'
+    JG_1 %bb.2.hit, implicit %eflags
+
+  bb.1.less:
+    %eax = MOV32r0 implicit-def %eflags
+
+  bb.2.exit:
+    RETQ %eax
 ...