[MIR] Print target-specific constant pools

This should enable us to test the generation of target-specific constant
pools, e.g. for ARM:

constants:
 - id:              0
   value:           'g(GOT_PREL)-(LPC0+8-.)'
   alignment:       4
   isTargetSpecific: true

I intend to use this to test PIC support in GlobalISel for ARM.

This is difficult to test outside of that context, since the existing
MIR tests usually rely on parser support as well, and that seems a bit
trickier to add. We could try to add a unit test, but the setup for that
seems rather convoluted and overkill.

We do test however that the parser reports a nice error when
encountering a target-specific constant pool.

Differential Revision: https://reviews.llvm.org/D36092

llvm-svn: 309806

llvm/include/llvm/CodeGen/MIRYamlMapping.h

@@ -310,9 +310,11 @@ struct MachineConstantPoolValue {
   UnsignedValue ID;
   StringValue Value;
   unsigned Alignment = 0;
+  bool IsTargetSpecific = false;
   bool operator==(const MachineConstantPoolValue &Other) const {
     return ID == Other.ID && Value == Other.Value &&
-           Alignment == Other.Alignment;
+           Alignment == Other.Alignment &&
+           IsTargetSpecific == Other.IsTargetSpecific;
   }
 };
 
@@ -321,6 +323,7 @@ template <> struct MappingTraits<MachineConstantPoolValue> {
     YamlIO.mapRequired("id", Constant.ID);
     YamlIO.mapOptional("value", Constant.Value, StringValue());
     YamlIO.mapOptional("alignment", Constant.Alignment, (unsigned)0);
+    YamlIO.mapOptional("isTargetSpecific", Constant.IsTargetSpecific, false);
   }
 };
 

llvm/lib/CodeGen/MIRParser/MIRParser.cpp

@@ -719,6 +719,10 @@ bool MIRParserImpl::initializeConstantPool(PerFunctionMIParsingState &PFS,
   const auto &M = *MF.getFunction()->getParent();
   SMDiagnostic Error;
   for (const auto &YamlConstant : YamlMF.Constants) {
+    if (YamlConstant.IsTargetSpecific)
+      // FIXME: Support target-specific constant pools
+      return error(YamlConstant.Value.SourceRange.Start,
+                   "Can't parse target-specific constant pool entries yet");
     const Constant *Value = dyn_cast_or_null<Constant>(
         parseConstantValue(YamlConstant.Value.Value, Error, M));
     if (!Value)

llvm/lib/CodeGen/MIRPrinter.cpp

@@ -458,17 +458,20 @@ void MIRPrinter::convert(yaml::MachineFunction &MF,
                          const MachineConstantPool &ConstantPool) {
   unsigned ID = 0;
   for (const MachineConstantPoolEntry &Constant : ConstantPool.getConstants()) {
-    // TODO: Serialize target specific constant pool entries.
-    if (Constant.isMachineConstantPoolEntry())
-      llvm_unreachable("Can't print target specific constant pool entries yet");
-
-    yaml::MachineConstantPoolValue YamlConstant;
     std::string Str;
     raw_string_ostream StrOS(Str);
-    Constant.Val.ConstVal->printAsOperand(StrOS);
+    if (Constant.isMachineConstantPoolEntry()) {
+      Constant.Val.MachineCPVal->print(StrOS);
+    } else {
+      Constant.Val.ConstVal->printAsOperand(StrOS);
+    }
+
+    yaml::MachineConstantPoolValue YamlConstant;
     YamlConstant.ID = ID++;
     YamlConstant.Value = StrOS.str();
     YamlConstant.Alignment = Constant.getAlignment();
+    YamlConstant.IsTargetSpecific = Constant.isMachineConstantPoolEntry();
+
     MF.Constants.push_back(YamlConstant);
   }
 }

llvm/test/CodeGen/MIR/ARM/target-constant-pools-error.mir

@@ -0,0 +1,27 @@
+# RUN: not llc -mtriple arm-unknown -run-pass none -o /dev/null %s 2>&1 | FileCheck %s
+--- |
+  target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+
+  @g = private global i32 4
+  define void @target_constant_pool() { ret void }
+...
+---
+name:            target_constant_pool
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: gpr, preferred-register: '' }
+  - { id: 1, class: gpr, preferred-register: '' }
+constants:
+  - id:              0
+  # CHECK: [[@LINE+1]]:22: Can't parse target-specific constant pool entries yet
+    value:           'g-(LPC0+8)'
+    alignment:       4
+    isTargetSpecific: true
+body:             |
+  bb.0.entry:
+    %0 = LDRi12 %const.0, 0, 14, _ :: (load 4 from constant-pool)
+    %1 = PICLDR killed %0, 0, 14, _ :: (dereferenceable load 4 from @g)
+    %r0 = COPY %1
+    BX_RET 14, _, implicit %r0
+
+...

llvm/test/CodeGen/MIR/X86/constant-pool.mir

@@ -46,9 +46,11 @@
 # CHECK-NEXT: - id: 0
 # CHECK-NEXT:   value: 'double 3.250000e+00'
 # CHECK-NEXT:   alignment: 8
+# CHECK-NEXT:   isTargetSpecific: false
 # CHECK-NEXT: - id: 1
 # CHECK-NEXT:   value: 'float 6.250000e+00'
 # CHECK-NEXT:   alignment: 4
+# CHECK-NEXT:   isTargetSpecific: false
 name:            test
 constants:
   - id:          0
@@ -74,9 +76,11 @@ body: |
 # CHECK-NEXT: - id: 0
 # CHECK-NEXT:   value: 'double 3.250000e+00'
 # CHECK-NEXT:   alignment: 8
+# CHECK-NEXT:   isTargetSpecific: false
 # CHECK-NEXT: - id: 1
 # CHECK-NEXT:   value: 'float 6.250000e+00'
 # CHECK-NEXT:   alignment: 4
+# CHECK-NEXT:   isTargetSpecific: false
 name:            test2
 constants:
   - id:          0
@@ -98,9 +102,11 @@ body: |
 # CHECK-NEXT: - id: 0
 # CHECK-NEXT:   value: 'double 3.250000e+00'
 # CHECK-NEXT:   alignment: 128
+# CHECK-NEXT:   isTargetSpecific: false
 # CHECK-NEXT: - id: 1
 # CHECK-NEXT:   value: 'float 6.250000e+00'
 # CHECK-NEXT:   alignment: 1
+# CHECK-NEXT:   isTargetSpecific: false
 name:            test3
 constants:
   - id:          0