[YAML] Add an optional argument `EnumMask` to the `yaml::IO::bitSetCase()`.

Some bit-set fields used in ELF file headers in fact contain two parts.
The first one is a regular bit-field. The second one is an enumeraion.
For example ELF header `e_flags` for MIPS target might contain the
following values:

Bit-set values:

  EF_MIPS_NOREORDER = 0x00000001
  EF_MIPS_PIC       = 0x00000002
  EF_MIPS_CPIC      = 0x00000004
  EF_MIPS_ABI2      = 0x00000020

Enumeration:

  EF_MIPS_ARCH_32   = 0x50000000
  EF_MIPS_ARCH_64   = 0x60000000
  EF_MIPS_ARCH_32R2 = 0x70000000
  EF_MIPS_ARCH_64R2 = 0x80000000

For printing bit-sets we use the `yaml::IO::bitSetCase()`. It does not
support bit-set/enumeration combinations and prints too many flags from
an enumeration part. This patch fixes this problem. New method
`yaml::IO::maskedBitSetCase()` handle "enumeration" part of bitset
defined by provided mask.

Patch reviewed by Nick Kledzik and Sean Silva.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209504 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 70 insertions, 19 deletions

diff --git a/docs/YamlIO.rst b/docs/YamlIO.rst
index dfb348da2f..76dd021f82 100644
--- a/docs/YamlIO.rst
+++ b/docs/YamlIO.rst
@@ -399,6 +399,42 @@ the above schema, a same valid YAML document is:
     name:    Tom
     flags:   [ pointy, flat ]
 
+Sometimes a "flags" field might contains an enumeration part
+defined by a bit-mask.
+
+.. code-block:: c++
+
+    enum {
+      flagsFeatureA = 1,
+      flagsFeatureB = 2,
+      flagsFeatureC = 4,
+
+      flagsCPUMask = 24,
+
+      flagsCPU1 = 8,
+      flagsCPU2 = 16
+    };
+
+To support reading and writing such fields, you need to use the maskedBitSet()
+method and provide the bit values, their names and the enumeration mask.
+
+.. code-block:: c++
+
+    template <>
+    struct ScalarBitSetTraits<MyFlags> {
+      static void bitset(IO &io, MyFlags &value) {
+        io.bitSetCase(value, "featureA",  flagsFeatureA);
+        io.bitSetCase(value, "featureB",  flagsFeatureB);
+        io.bitSetCase(value, "featureC",  flagsFeatureC);
+        io.maskedBitSetCase(value, "CPU1",  flagsCPU1, flagsCPUMask);
+        io.maskedBitSetCase(value, "CPU2",  flagsCPU2, flagsCPUMask);
+      }
+    };
+
+YAML I/O (when writing) will apply the enumeration mask to the flags field,
+and compare the result and values from the bitset. As in case of a regular
+bitset, each that matches will cause the corresponding string to be added
+to the flow sequence.
 
 Custom Scalar
 -------------
diff --git a/include/llvm/Support/YAMLTraits.h b/include/llvm/Support/YAMLTraits.h
index 7f4a922935..4ee05ed133 100644
--- a/include/llvm/Support/YAMLTraits.h
+++ b/include/llvm/Support/YAMLTraits.h
@@ -487,6 +487,19 @@ public:
     }
   }
 
+  template <typename T>
+  void maskedBitSetCase(T &Val, const char *Str, T ConstVal, T Mask) {
+    if (bitSetMatch(Str, outputting() && (Val & Mask) == ConstVal))
+      Val = Val | ConstVal;
+  }
+
+  template <typename T>
+  void maskedBitSetCase(T &Val, const char *Str, uint32_t ConstVal,
+                        uint32_t Mask) {
+    if (bitSetMatch(Str, outputting() && (Val & Mask) == ConstVal))
+      Val = Val | ConstVal;
+  }
+
   void *getContext();
   void setContext(void *);
 
diff --git a/lib/Object/ELFYAML.cpp b/lib/Object/ELFYAML.cpp
index 8329853340..7d50f23417 100644
--- a/lib/Object/ELFYAML.cpp
+++ b/lib/Object/ELFYAML.cpp
@@ -246,16 +246,17 @@ void ScalarBitSetTraits<ELFYAML::ELF_EF>::bitset(IO &IO,
   const auto *Object = static_cast<ELFYAML::Object *>(IO.getContext());
   assert(Object && "The IO context is not initialized");
 #define BCase(X) IO.bitSetCase(Value, #X, ELF::X);
+#define BCaseMask(X, M) IO.maskedBitSetCase(Value, #X, ELF::X, ELF::M);
   switch (Object->Header.Machine) {
   case ELF::EM_ARM:
     BCase(EF_ARM_SOFT_FLOAT)
     BCase(EF_ARM_VFP_FLOAT)
-    BCase(EF_ARM_EABI_UNKNOWN)
-    BCase(EF_ARM_EABI_VER1)
-    BCase(EF_ARM_EABI_VER2)
-    BCase(EF_ARM_EABI_VER3)
-    BCase(EF_ARM_EABI_VER4)
-    BCase(EF_ARM_EABI_VER5)
+    BCaseMask(EF_ARM_EABI_UNKNOWN, EF_ARM_EABIMASK)
+    BCaseMask(EF_ARM_EABI_VER1, EF_ARM_EABIMASK)
+    BCaseMask(EF_ARM_EABI_VER2, EF_ARM_EABIMASK)
+    BCaseMask(EF_ARM_EABI_VER3, EF_ARM_EABIMASK)
+    BCaseMask(EF_ARM_EABI_VER4, EF_ARM_EABIMASK)
+    BCaseMask(EF_ARM_EABI_VER5, EF_ARM_EABIMASK)
     break;
   case ELF::EM_MIPS:
     BCase(EF_MIPS_NOREORDER)
@@ -266,17 +267,17 @@ void ScalarBitSetTraits<ELFYAML::ELF_EF>::bitset(IO &IO,
     BCase(EF_MIPS_ABI_O32)
     BCase(EF_MIPS_MICROMIPS)
     BCase(EF_MIPS_ARCH_ASE_M16)
-    BCase(EF_MIPS_ARCH_1)
-    BCase(EF_MIPS_ARCH_2)
-    BCase(EF_MIPS_ARCH_3)
-    BCase(EF_MIPS_ARCH_4)
-    BCase(EF_MIPS_ARCH_5)
-    BCase(EF_MIPS_ARCH_32)
-    BCase(EF_MIPS_ARCH_64)
-    BCase(EF_MIPS_ARCH_32R2)
-    BCase(EF_MIPS_ARCH_64R2)
-    BCase(EF_MIPS_ARCH_32R6)
-    BCase(EF_MIPS_ARCH_64R6)
+    BCaseMask(EF_MIPS_ARCH_1, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_2, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_3, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_4, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_5, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_32, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_64, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_32R2, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_64R2, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_32R6, EF_MIPS_ARCH)
+    BCaseMask(EF_MIPS_ARCH_64R6, EF_MIPS_ARCH)
     break;
   case ELF::EM_HEXAGON:
     BCase(EF_HEXAGON_MACH_V2)
@@ -292,6 +293,7 @@ void ScalarBitSetTraits<ELFYAML::ELF_EF>::bitset(IO &IO,
     llvm_unreachable("Unsupported architecture");
   }
 #undef BCase
+#undef BCaseMask
 }
 
 void ScalarEnumerationTraits<ELFYAML::ELF_SHT>::enumeration(
diff --git a/test/Object/obj2yaml.test b/test/Object/obj2yaml.test
index db03f5afa4..1c1526349f 100644
--- a/test/Object/obj2yaml.test
+++ b/test/Object/obj2yaml.test
@@ -191,7 +191,7 @@ ELF-MIPSEL-NEXT:   Class:           ELFCLASS32
 ELF-MIPSEL-NEXT:   Data:            ELFDATA2LSB
 ELF-MIPSEL-NEXT:   Type:            ET_REL
 ELF-MIPSEL-NEXT:   Machine:         EM_MIPS
-ELF-MIPSEL-NEXT:   Flags:           [ EF_MIPS_NOREORDER, EF_MIPS_PIC, EF_MIPS_CPIC, EF_MIPS_ABI_O32, EF_MIPS_ARCH_1, EF_MIPS_ARCH_2, EF_MIPS_ARCH_5, EF_MIPS_ARCH_32 ]
+ELF-MIPSEL-NEXT:   Flags:           [ EF_MIPS_NOREORDER, EF_MIPS_PIC, EF_MIPS_CPIC, EF_MIPS_ABI_O32, EF_MIPS_ARCH_32 ]
 ELF-MIPSEL-NEXT: Sections:
 ELF-MIPSEL-NEXT:   - Name:            .text
 ELF-MIPSEL-NEXT:     Type:            SHT_PROGBITS
@@ -285,7 +285,7 @@ ELF-MIPS64EL-NEXT:   Class:           ELFCLASS64
 ELF-MIPS64EL-NEXT:   Data:            ELFDATA2LSB
 ELF-MIPS64EL-NEXT:   Type:            ET_REL
 ELF-MIPS64EL-NEXT:   Machine:         EM_MIPS
-ELF-MIPS64EL-NEXT:   Flags:           [ EF_MIPS_ARCH_1, EF_MIPS_ARCH_3 ]
+ELF-MIPS64EL-NEXT:   Flags:           [ EF_MIPS_ARCH_3 ]
 ELF-MIPS64EL-NEXT: Sections:
 ELF-MIPS64EL-NEXT:   - Name:            .text
 ELF-MIPS64EL-NEXT:     Type:            SHT_PROGBITS