MIR Parser: Report an error when parsing machine function with an empty body.

This commit adds a new error which is reported when the MIR Parser encounters
a machine function without any machine basic blocks. The machine verifier
expects that the machine functions have at least one MBB, and this error will
prevent machine functions without MBBs from reaching the machine verifier and
crashing with an assertion.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241862 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MIRParser/MIRParser.cpp

@@ -275,6 +275,9 @@ bool MIRParserImpl::initializeMachineFunction(MachineFunction &MF) {
                    Twine(YamlMBB.ID));
   }
 
+  if (YamlMF.BasicBlocks.empty())
+    return error(Twine("machine function '") + Twine(MF.getName()) +
+                 "' requires at least one machine basic block in its body");
   // Initialize the machine basic blocks after creating them all so that the
   // machine instructions parser can resolve the MBB references.
   unsigned I = 0;

test/CodeGen/MIR/llvmIR.mir

@@ -32,4 +32,6 @@
 ...
 ---
 name: foo
+body:
+  - id: 0
 ...

test/CodeGen/MIR/llvmIRMissing.mir

@@ -4,4 +4,6 @@
 ---
 # CHECK: name: foo
 name: foo
+body:
+  - id: 0
 ...

test/CodeGen/MIR/machine-function-missing-body-error.mir

@@ -0,0 +1,15 @@
+# RUN: not llc -start-after branch-folder -stop-after branch-folder -o /dev/null %s 2>&1 | FileCheck %s
+# This test ensures that the MIR parser reports an error when it encounters a
+# machine function with an empty body.
+
+--- |
+
+  define i32 @foo() {
+    ret i32 0
+  }
+
+...
+---
+# CHECK: machine function 'foo' requires at least one machine basic block in its body
+name:            foo
+...

test/CodeGen/MIR/machine-function-missing-function.mir

@@ -12,8 +12,12 @@
 ...
 ---
 name:            foo
+body:
+  - id: 0
 ...
 ---
 # CHECK: function 'faa' isn't defined in the provided LLVM IR
 name:            faa
+body:
+  - id: 0
 ...

test/CodeGen/MIR/machine-function-missing-name.mir

@@ -16,7 +16,11 @@
 ---
 # CHECK: [[@LINE+1]]:1: missing required key 'name'
 nme:             foo
+body:
+  - id: 0
 ...
 ---
 name:            bar
+body:
+  - id: 0
 ...

test/CodeGen/MIR/machine-function.mir

@@ -27,6 +27,8 @@
 # CHECK-NEXT: hasInlineAsm: false
 # CHECK: ...
 name:            foo
+body:
+  - id: 0
 ...
 ---
 # CHECK: name: bar
@@ -35,6 +37,8 @@ name:            foo
 # CHECK-NEXT: hasInlineAsm: false
 # CHECK: ...
 name:            bar
+body:
+  - id: 0
 ...
 ---
 # CHECK: name: func
@@ -44,6 +48,8 @@ name:            bar
 # CHECK: ...
 name:            func
 alignment:       8
+body:
+  - id: 0
 ...
 ---
 # CHECK: name: func2
@@ -55,4 +61,6 @@ name:            func2
 alignment:       16
 exposesReturnsTwice: true
 hasInlineAsm:    true
+body:
+  - id: 0
 ...

test/CodeGen/MIR/register-info.mir

@@ -22,6 +22,8 @@
 # CHECK-NEXT: tracksSubRegLiveness: false
 # CHECK: ...
 name:            foo
+body:
+  - id: 0
 ...
 ---
 # CHECK: name: bar
@@ -33,4 +35,6 @@ name: bar
 isSSA: false
 tracksRegLiveness: true
 tracksSubRegLiveness: true
+body:
+  - id: 0
 ...