[yaml2obj] Remove --format option in favor of YAML tags

Summary:
Our YAML library's handling of tags isn't perfect, but it is good enough to get rid of the need for the --format argument to yaml2obj. This patch does exactly that.

Instead of requiring --format, it infers the format based on the tags found in the object file. The supported tags are:

!ELF
!COFF
!mach-o
!fat-mach-o

I have a corresponding patch that is quite large that fixes up all the in-tree test cases.

Reviewers: rafael, Bigcheese, compnerd, silvas

Subscribers: compnerd, llvm-commits

Differential Revision: http://reviews.llvm.org/D21711

llvm-svn: 273915

63 files changed, 111 insertions, 87 deletions

diff --git a/llvm/test/Object/AArch64/yaml2obj-elf-aarch64-rel.yaml b/llvm/test/Object/AArch64/yaml2obj-elf-aarch64-rel.yaml
index c27e888a47c..e3017a24a97 100644
--- a/llvm/test/Object/AArch64/yaml2obj-elf-aarch64-rel.yaml
+++ b/llvm/test/Object/AArch64/yaml2obj-elf-aarch64-rel.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t
+# RUN: yaml2obj %s > %t
 # RUN: obj2yaml  %t | FileCheck %s
 
 # CHECK:      - Name:            .rela.text
@@ -14,6 +14,7 @@
 # CHECK-NEXT:        Symbol:          main
 # CHECK-NEXT:        Type:            R_AARCH64_TLSGD_ADR_PREL21
 
+!ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
diff --git a/llvm/test/Object/AMDGPU/elf-definitios.yaml b/llvm/test/Object/AMDGPU/elf-definitios.yaml
index 6d535095123..819786aa190 100644
--- a/llvm/test/Object/AMDGPU/elf-definitios.yaml
+++ b/llvm/test/Object/AMDGPU/elf-definitios.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t.o
+# RUN: yaml2obj %s > %t.o
 # RUN: llvm-readobj -s -file-headers %t.o | FileCheck %s
 
 # CHECK: Format: ELF64-amdgpu-hsacobj
@@ -14,7 +14,7 @@
 # CHECK: SHF_AMDGPU_HSA_READONLY (0x200000)
 # CHECK: }
 
----
+--- !ELF
 FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB
diff --git a/llvm/test/Object/AMDGPU/elf32-unknown.yaml b/llvm/test/Object/AMDGPU/elf32-unknown.yaml
index 708db8dc9fc..c4305950607 100644
--- a/llvm/test/Object/AMDGPU/elf32-unknown.yaml
+++ b/llvm/test/Object/AMDGPU/elf32-unknown.yaml
@@ -1,9 +1,9 @@
-# RUN: yaml2obj -format=elf %s > %t.o
+# RUN: yaml2obj %s > %t.o
 # RUN: llvm-readobj -s -file-headers %t.o | FileCheck %s
 
 # CHECK: Format: ELF32-amdgpu
 
----
+--- !ELF
 FileHeader:
   Class:   ELFCLASS32
   Data:    ELFDATA2LSB
diff --git a/llvm/test/Object/AMDGPU/elf64-relocs.yaml b/llvm/test/Object/AMDGPU/elf64-relocs.yaml
index 8ccf25b8605..896fcdbefa0 100644
--- a/llvm/test/Object/AMDGPU/elf64-relocs.yaml
+++ b/llvm/test/Object/AMDGPU/elf64-relocs.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t
+# RUN: yaml2obj %s > %t
 # RUN: llvm-readobj -r %t | FileCheck %s
 
 # CHECK: Relocations [
@@ -13,6 +13,7 @@
 # CHECK:   }
 # CHECK: ]
 
+!ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
diff --git a/llvm/test/Object/AMDGPU/elf64-unknown.yaml b/llvm/test/Object/AMDGPU/elf64-unknown.yaml
index cae248854ad..c8272932381 100644
--- a/llvm/test/Object/AMDGPU/elf64-unknown.yaml
+++ b/llvm/test/Object/AMDGPU/elf64-unknown.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t.o
+# RUN: yaml2obj %s > %t.o
 # RUN: llvm-readobj -s -file-headers %t.o | FileCheck %s
 
 # CHECK: Format: ELF64-amdgpu
diff --git a/llvm/test/Object/Inputs/COFF/i386.yaml b/llvm/test/Object/Inputs/COFF/i386.yaml
index 7873df0a7e2..ad1a4f100fa 100644
--- a/llvm/test/Object/Inputs/COFF/i386.yaml
+++ b/llvm/test/Object/Inputs/COFF/i386.yaml
@@ -1,3 +1,4 @@
+!COFF
 header: !Header
   Machine: IMAGE_FILE_MACHINE_I386 # (0x14c)
   Characteristics: [ IMAGE_FILE_DEBUG_STRIPPED ]
diff --git a/llvm/test/Object/Inputs/COFF/long-file-symbol.yaml b/llvm/test/Object/Inputs/COFF/long-file-symbol.yaml
index 37caad79620..4a37a433e43 100644
--- a/llvm/test/Object/Inputs/COFF/long-file-symbol.yaml
+++ b/llvm/test/Object/Inputs/COFF/long-file-symbol.yaml
@@ -1,4 +1,4 @@
----
+--- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_AMD64
   Characteristics: [ IMAGE_FILE_RELOCS_STRIPPED, IMAGE_FILE_LINE_NUMS_STRIPPED ]
diff --git a/llvm/test/Object/Inputs/COFF/long-section-name.yaml b/llvm/test/Object/Inputs/COFF/long-section-name.yaml
index a86f9019cd5..12041858317 100644
--- a/llvm/test/Object/Inputs/COFF/long-section-name.yaml
+++ b/llvm/test/Object/Inputs/COFF/long-section-name.yaml
@@ -1,4 +1,4 @@
----
+--- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_I386
   Characteristics: [ IMAGE_FILE_RELOCS_STRIPPED, IMAGE_FILE_LINE_NUMS_STRIPPED, IMAGE_FILE_LOCAL_SYMS_STRIPPED, IMAGE_FILE_32BIT_MACHINE ]
diff --git a/llvm/test/Object/Inputs/COFF/section-aux-symbol.yaml b/llvm/test/Object/Inputs/COFF/section-aux-symbol.yaml
index 623af558959..67fba68afd4 100644
--- a/llvm/test/Object/Inputs/COFF/section-aux-symbol.yaml
+++ b/llvm/test/Object/Inputs/COFF/section-aux-symbol.yaml
@@ -1,4 +1,4 @@
----
+--- !COFF
 header:          
   Machine:         IMAGE_FILE_MACHINE_I386
   Characteristics: [ IMAGE_FILE_RELOCS_STRIPPED, IMAGE_FILE_EXECUTABLE_IMAGE, IMAGE_FILE_LINE_NUMS_STRIPPED, IMAGE_FILE_32BIT_MACHINE, IMAGE_FILE_DEBUG_STRIPPED ]
diff --git a/llvm/test/Object/Inputs/COFF/weak-external.yaml b/llvm/test/Object/Inputs/COFF/weak-external.yaml
index 064b44a4a38..3963bcdc557 100644
--- a/llvm/test/Object/Inputs/COFF/weak-external.yaml
+++ b/llvm/test/Object/Inputs/COFF/weak-external.yaml
@@ -1,4 +1,4 @@
----
+--- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_I386
   Characteristics: [ IMAGE_FILE_LINE_NUMS_STRIPPED, IMAGE_FILE_32BIT_MACHINE ]
diff --git a/llvm/test/Object/Inputs/COFF/weak-externals.yaml b/llvm/test/Object/Inputs/COFF/weak-externals.yaml
index 44364186b52..d0ec3137c71 100644
--- a/llvm/test/Object/Inputs/COFF/weak-externals.yaml
+++ b/llvm/test/Object/Inputs/COFF/weak-externals.yaml
@@ -1,4 +1,4 @@
----
+--- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_ARMNT
   Characteristics: [  ]
diff --git a/llvm/test/Object/Inputs/COFF/x86-64.yaml b/llvm/test/Object/Inputs/COFF/x86-64.yaml
index b8a863a429c..2fd5a4d19ff 100644
--- a/llvm/test/Object/Inputs/COFF/x86-64.yaml
+++ b/llvm/test/Object/Inputs/COFF/x86-64.yaml
@@ -1,3 +1,4 @@
+!COFF
 header: !Header
   Machine: IMAGE_FILE_MACHINE_AMD64 # (0x8664)
 
diff --git a/llvm/test/Object/Lanai/yaml2obj-elf-lanai-rel.yaml b/llvm/test/Object/Lanai/yaml2obj-elf-lanai-rel.yaml
index aa45ca16b34..df81a5b8bde 100644
--- a/llvm/test/Object/Lanai/yaml2obj-elf-lanai-rel.yaml
+++ b/llvm/test/Object/Lanai/yaml2obj-elf-lanai-rel.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t
+# RUN: yaml2obj %s > %t
 # RUN: llvm-readobj -r %t | FileCheck %s
 
 # CHECK:      Relocations [
@@ -13,6 +13,7 @@
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]
 
+!ELF
 FileHeader:
   Class:           ELFCLASS32
   Data:            ELFDATA2LSB
diff --git a/llvm/test/Object/Mips/abi-flags.yaml b/llvm/test/Object/Mips/abi-flags.yaml
index 8a11fc4124c..0d9fb369423 100644
--- a/llvm/test/Object/Mips/abi-flags.yaml
+++ b/llvm/test/Object/Mips/abi-flags.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t
+# RUN: yaml2obj %s > %t
 # RUN: llvm-readobj -mips-abi-flags %t | FileCheck -check-prefix=OBJ %s
 # RUN: obj2yaml %t | FileCheck -check-prefix=YAML %s
 
@@ -34,6 +34,7 @@
 # YAML-NEXT:   CPR1Size:        REG_64
 # YAML-NEXT:   Flags1:          [ ODDSPREG ]
 
+!ELF
 FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2MSB
diff --git a/llvm/test/Object/Mips/elf-abi.yaml b/llvm/test/Object/Mips/elf-abi.yaml
index 5f11b14da59..7d8e1ceca2d 100644
--- a/llvm/test/Object/Mips/elf-abi.yaml
+++ b/llvm/test/Object/Mips/elf-abi.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf -docnum=1 %s > %t.o32
+# RUN: yaml2obj -docnum=1 %s > %t.o32
 # RUN: llvm-readobj -file-headers %t.o32 | FileCheck -check-prefix=O32OBJ %s
 # RUN: obj2yaml %t.o32 | FileCheck -check-prefix=O32YAML %s
 
@@ -10,7 +10,7 @@
 
 # O32YAML:  Flags:  [ EF_MIPS_PIC, EF_MIPS_ABI_O32, EF_MIPS_ARCH_32 ]
 
-# RUN: yaml2obj -format=elf -docnum=2 %s > %t.o64
+# RUN: yaml2obj -docnum=2 %s > %t.o64
 # RUN: llvm-readobj -file-headers %t.o64 | FileCheck -check-prefix=O64OBJ %s
 # RUN: obj2yaml %t.o64 | FileCheck -check-prefix=O64YAML %s
 
@@ -22,7 +22,7 @@
 
 # O64YAML:  Flags:  [ EF_MIPS_PIC, EF_MIPS_ABI_O64, EF_MIPS_ARCH_64 ]
 
-# RUN: yaml2obj -format=elf -docnum=3 %s > %t.eabi32
+# RUN: yaml2obj -docnum=3 %s > %t.eabi32
 # RUN: llvm-readobj -file-headers %t.eabi32 | FileCheck -check-prefix=E32OBJ %s
 # RUN: obj2yaml %t.eabi32 | FileCheck -check-prefix=E32YAML %s
 
@@ -34,7 +34,7 @@
 
 # E32YAML:  Flags:  [ EF_MIPS_PIC, EF_MIPS_ABI_EABI32, EF_MIPS_ARCH_32 ]
 
-# RUN: yaml2obj -format=elf -docnum=4 %s > %t.eabi64
+# RUN: yaml2obj -docnum=4 %s > %t.eabi64
 # RUN: llvm-readobj -file-headers %t.eabi64 | FileCheck -check-prefix=E64OBJ %s
 # RUN: obj2yaml %t.eabi64 | FileCheck -check-prefix=E64YAML %s
 
@@ -47,7 +47,7 @@
 # E64YAML:  Flags:  [ EF_MIPS_PIC, EF_MIPS_ABI_EABI64, EF_MIPS_ARCH_64 ]
 
 # o32
----
+--- !ELF
 FileHeader:
   Class:           ELFCLASS32
   Data:            ELFDATA2LSB
diff --git a/llvm/test/Object/Mips/elf-flags.yaml b/llvm/test/Object/Mips/elf-flags.yaml
index f79be9d4e07..dceabc05c8b 100644
--- a/llvm/test/Object/Mips/elf-flags.yaml
+++ b/llvm/test/Object/Mips/elf-flags.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t
+# RUN: yaml2obj %s > %t
 # RUN: llvm-readobj -file-headers %t | FileCheck -check-prefix=OBJ %s
 # RUN: obj2yaml %t | FileCheck -check-prefix=YAML %s
 
@@ -25,7 +25,7 @@
 # YAML-NEXT:   Machine:         EM_MIPS
 # YAML-NEXT:   Flags:           [ EF_MIPS_NOREORDER, EF_MIPS_PIC, EF_MIPS_CPIC, EF_MIPS_ABI2, EF_MIPS_32BITMODE, EF_MIPS_FP64, EF_MIPS_NAN2008, EF_MIPS_MICROMIPS, EF_MIPS_ARCH_ASE_M16, EF_MIPS_ARCH_ASE_MDMX, EF_MIPS_ABI_O32, EF_MIPS_MACH_OCTEON, EF_MIPS_ARCH_32R6 ]
 
----
+--- !ELF
 FileHeader:
   Class:    ELFCLASS32
   Data:     ELFDATA2LSB
diff --git a/llvm/test/Object/Mips/elf-mips64-rel.yaml b/llvm/test/Object/Mips/elf-mips64-rel.yaml
index 7c41b78e6ad..3e565553475 100644
--- a/llvm/test/Object/Mips/elf-mips64-rel.yaml
+++ b/llvm/test/Object/Mips/elf-mips64-rel.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t
+# RUN: yaml2obj %s > %t
 # RUN: llvm-readobj -r %t | FileCheck -check-prefix=OBJ %s
 # RUN: obj2yaml %t | FileCheck -check-prefix=YAML %s
 
@@ -41,7 +41,7 @@
 # YAML-NEXT:     Type2:       R_MIPS_LO16
 # YAML-NEXT:     SpecSym:     RSS_GP0
 
----
+--- !ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
diff --git a/llvm/test/Object/X86/yaml2obj-elf-x86-rel.yaml b/llvm/test/Object/X86/yaml2obj-elf-x86-rel.yaml
index 5ca6614d238..0cb26fca995 100644
--- a/llvm/test/Object/X86/yaml2obj-elf-x86-rel.yaml
+++ b/llvm/test/Object/X86/yaml2obj-elf-x86-rel.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s > %t
+# RUN: yaml2obj %s > %t
 # RUN: llvm-readobj -r %t | FileCheck %s
 
 # CHECK:      Relocations [
@@ -7,6 +7,7 @@
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]
 
+!ELF
 FileHeader:
   Class:           ELFCLASS32
   Data:            ELFDATA2LSB
diff --git a/llvm/test/Object/elf-unknown-type.test b/llvm/test/Object/elf-unknown-type.test
index 9993c096376..1ef4f58085d 100644
--- a/llvm/test/Object/elf-unknown-type.test
+++ b/llvm/test/Object/elf-unknown-type.test
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -file-headers - | FileCheck %s
+# RUN: yaml2obj %s | llvm-readobj -file-headers - | FileCheck %s
 
 !ELF
 FileHeader: !FileHeader
diff --git a/llvm/test/Object/obj2yaml-sectiongroup.test b/llvm/test/Object/obj2yaml-sectiongroup.test
index 66e8e3875be..2387c75494f 100644
--- a/llvm/test/Object/obj2yaml-sectiongroup.test
+++ b/llvm/test/Object/obj2yaml-sectiongroup.test
@@ -1,7 +1,7 @@
 # Checks that the tool is able to read section groups with ELF.
 RUN: obj2yaml %p/Inputs/sectionGroup.elf.x86-64 > %t1.sectiongroup.yaml
 RUN: FileCheck %s --check-prefix ELF-GROUP < %t1.sectiongroup.yaml
-RUN: yaml2obj -format=elf %t1.sectiongroup.yaml -o %t2.o.elf
+RUN: yaml2obj %t1.sectiongroup.yaml -o %t2.o.elf
 RUN: llvm-readobj -sections %t2.o.elf | FileCheck %s -check-prefix=SECTIONS
 #ELF-GROUP:  - Name:            .group
 #ELF-GROUP:    Type:            SHT_GROUP
diff --git a/llvm/test/Object/yaml2obj-coff-invalid-alignment.test b/llvm/test/Object/yaml2obj-coff-invalid-alignment.test
index f76f063dc44..3e760310f57 100644
--- a/llvm/test/Object/yaml2obj-coff-invalid-alignment.test
+++ b/llvm/test/Object/yaml2obj-coff-invalid-alignment.test
@@ -2,7 +2,7 @@
 
 # CHECK: Section alignment is too large
 
----
+--- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_AMD64
   Characteristics: []
diff --git a/llvm/test/Object/yaml2obj-coff-multi-doc.test b/llvm/test/Object/yaml2obj-coff-multi-doc.test
index 1cf720306bf..0335a72bfcf 100644
--- a/llvm/test/Object/yaml2obj-coff-multi-doc.test
+++ b/llvm/test/Object/yaml2obj-coff-multi-doc.test
@@ -1,15 +1,15 @@
-# RUN: yaml2obj -format=coff -docnum=1 %s \
+# RUN: yaml2obj -docnum=1 %s \
 # RUN:   | llvm-readobj -symbols - | FileCheck -check-prefix=DOC1 %s
-# RUN: yaml2obj -format=coff -docnum=2 %s \
+# RUN: yaml2obj -docnum=2 %s \
 # RUN:   | llvm-readobj -symbols - | FileCheck -check-prefix=DOC2 %s
-# RUN: not yaml2obj -format=coff -docnum=3 %s 2>&1 \
+# RUN: not yaml2obj -docnum=3 %s 2>&1 \
 # RUN:   | FileCheck -check-prefix=DOC3 %s
 
 # DOC1: Name: _sym1
 # DOC2: Name: _sym2
 # DOC3: yaml2obj: Cannot find the 3rd document
 
----
+--- !COFF
 header:
   Machine: IMAGE_FILE_MACHINE_I386
   Characteristics: [ IMAGE_FILE_DEBUG_STRIPPED ]
@@ -49,7 +49,7 @@ symbols:
     ComplexType: IMAGE_SYM_DTYPE_NULL
     StorageClass: IMAGE_SYM_CLASS_EXTERNAL
 
----
+--- !COFF
 header:
   Machine: IMAGE_FILE_MACHINE_I386
   Characteristics: [ IMAGE_FILE_DEBUG_STRIPPED ]
diff --git a/llvm/test/Object/yaml2obj-elf-alignment.yaml b/llvm/test/Object/yaml2obj-elf-alignment.yaml
index 8f2f985177f..341966d9a5b 100644
--- a/llvm/test/Object/yaml2obj-elf-alignment.yaml
+++ b/llvm/test/Object/yaml2obj-elf-alignment.yaml
@@ -1,6 +1,6 @@
 # Check that yaml2obj takes in account section AddressAlign field.
 
-# RUN: yaml2obj -format=elf %s > %t
+# RUN: yaml2obj %s > %t
 # RUN: llvm-readobj -s %t | FileCheck %s
 
 # CHECK:      Section {
@@ -20,7 +20,7 @@
 # CHECK-NEXT:   EntrySize: 0
 # CHECK-NEXT: }
 
----
+--- !ELF
 FileHeader:
   Class:    ELFCLASS32
   Data:     ELFDATA2LSB
diff --git a/llvm/test/Object/yaml2obj-elf-bits-endian.test b/llvm/test/Object/yaml2obj-elf-bits-endian.test
index 4be9a4465b8..e8bd2f1d8d1 100644
--- a/llvm/test/Object/yaml2obj-elf-bits-endian.test
+++ b/llvm/test/Object/yaml2obj-elf-bits-endian.test
@@ -1,7 +1,7 @@
-RUN: yaml2obj -format=elf %p/Inputs/ELF/LE64.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix LE64
-RUN: yaml2obj -format=elf %p/Inputs/ELF/BE64.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix BE64
-RUN: yaml2obj -format=elf %p/Inputs/ELF/LE32.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix LE32
-RUN: yaml2obj -format=elf %p/Inputs/ELF/BE32.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix BE32
+RUN: yaml2obj %p/Inputs/ELF/LE64.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix LE64
+RUN: yaml2obj %p/Inputs/ELF/BE64.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix BE64
+RUN: yaml2obj %p/Inputs/ELF/LE32.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix LE32
+RUN: yaml2obj %p/Inputs/ELF/BE32.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix BE32
 
 LE64:      Class: 64-bit (0x2)
 LE64-NEXT: DataEncoding: LittleEndian (0x1)
diff --git a/llvm/test/Object/yaml2obj-elf-file-headers-with-e_flags.yaml b/llvm/test/Object/yaml2obj-elf-file-headers-with-e_flags.yaml
index dddc7d97f62..ad032e80d64 100644
--- a/llvm/test/Object/yaml2obj-elf-file-headers-with-e_flags.yaml
+++ b/llvm/test/Object/yaml2obj-elf-file-headers-with-e_flags.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -file-headers - | FileCheck %s
+# RUN: yaml2obj %s | llvm-readobj -file-headers - | FileCheck %s
 !ELF
 FileHeader:
   Class: ELFCLASS32
diff --git a/llvm/test/Object/yaml2obj-elf-file-headers.yaml b/llvm/test/Object/yaml2obj-elf-file-headers.yaml
index 285170170a2..4dfee5f9387 100644
--- a/llvm/test/Object/yaml2obj-elf-file-headers.yaml
+++ b/llvm/test/Object/yaml2obj-elf-file-headers.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -file-headers - | FileCheck %s
+# RUN: yaml2obj %s | llvm-readobj -file-headers - | FileCheck %s
 !ELF
 FileHeader:
   Class: ELFCLASS64
diff --git a/llvm/test/Object/yaml2obj-elf-multi-doc.test b/llvm/test/Object/yaml2obj-elf-multi-doc.test
index c51f803300e..b3c8335a36b 100644
--- a/llvm/test/Object/yaml2obj-elf-multi-doc.test
+++ b/llvm/test/Object/yaml2obj-elf-multi-doc.test
@@ -1,8 +1,8 @@
-# RUN: yaml2obj -format=elf -docnum=1 %s \
+# RUN: yaml2obj -docnum=1 %s \
 # RUN:   | llvm-readobj -symbols - | FileCheck -check-prefix=DOC1 %s
-# RUN: yaml2obj -format=elf -docnum=2 %s \
+# RUN: yaml2obj -docnum=2 %s \
 # RUN:   | llvm-readobj -symbols - | FileCheck -check-prefix=DOC2 %s
-# RUN: not yaml2obj -format=elf -docnum=3 %s 2>&1 \
+# RUN: not yaml2obj -docnum=3 %s 2>&1 \
 # RUN:   | FileCheck -check-prefix=DOC3 %s
 
 # DOC1: Name: T1 (1)
diff --git a/llvm/test/Object/yaml2obj-elf-rel-noref.yaml b/llvm/test/Object/yaml2obj-elf-rel-noref.yaml
index 4a13acd1fd3..8eb6b0dca3b 100644
--- a/llvm/test/Object/yaml2obj-elf-rel-noref.yaml
+++ b/llvm/test/Object/yaml2obj-elf-rel-noref.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -sections -relocations - | FileCheck %s
+# RUN: yaml2obj %s | llvm-readobj -sections -relocations - | FileCheck %s
 
 !ELF
 FileHeader:        !FielHeader
diff --git a/llvm/test/Object/yaml2obj-elf-rel.yaml b/llvm/test/Object/yaml2obj-elf-rel.yaml
index ba3640cfefa..f98c8e262a7 100644
--- a/llvm/test/Object/yaml2obj-elf-rel.yaml
+++ b/llvm/test/Object/yaml2obj-elf-rel.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -sections -relocations - | FileCheck %s
+# RUN: yaml2obj %s | llvm-readobj -sections -relocations - | FileCheck %s
 
 !ELF
 FileHeader: !FileHeader
diff --git a/llvm/test/Object/yaml2obj-elf-section-basic.yaml b/llvm/test/Object/yaml2obj-elf-section-basic.yaml
index 69d3ae91b71..c2dde8c26ff 100644
--- a/llvm/test/Object/yaml2obj-elf-section-basic.yaml
+++ b/llvm/test/Object/yaml2obj-elf-section-basic.yaml
@@ -1,5 +1,5 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -sections -section-data - | FileCheck %s
-# RUN: yaml2obj -format=elf -o %t %s
+# RUN: yaml2obj %s | llvm-readobj -sections -section-data - | FileCheck %s
+# RUN: yaml2obj -o %t %s
 # RUN: llvm-readobj -sections -section-data %t | FileCheck %s
 
 !ELF
diff --git a/llvm/test/Object/yaml2obj-elf-section-invalid-size.yaml b/llvm/test/Object/yaml2obj-elf-section-invalid-size.yaml
index d0cb370072d..b896c9d6afc 100644
--- a/llvm/test/Object/yaml2obj-elf-section-invalid-size.yaml
+++ b/llvm/test/Object/yaml2obj-elf-section-invalid-size.yaml
@@ -1,4 +1,4 @@
-# RUN: not yaml2obj -format=elf -o %t %s 2>&1 | FileCheck %s
+# RUN: not yaml2obj -o %t %s 2>&1 | FileCheck %s
 
 !ELF
 FileHeader:
diff --git a/llvm/test/Object/yaml2obj-elf-symbol-LocalGlobalWeak.yaml b/llvm/test/Object/yaml2obj-elf-symbol-LocalGlobalWeak.yaml
index 3c4e830c0df..c044d711a34 100644
--- a/llvm/test/Object/yaml2obj-elf-symbol-LocalGlobalWeak.yaml
+++ b/llvm/test/Object/yaml2obj-elf-symbol-LocalGlobalWeak.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -symbols - | FileCheck %s
+# RUN: yaml2obj %s | llvm-readobj -symbols - | FileCheck %s
 !ELF
 FileHeader:
   Class: ELFCLASS64
diff --git a/llvm/test/Object/yaml2obj-elf-symbol-basic.yaml b/llvm/test/Object/yaml2obj-elf-symbol-basic.yaml
index b17c0429bd4..e1f5ce4e725 100644
--- a/llvm/test/Object/yaml2obj-elf-symbol-basic.yaml
+++ b/llvm/test/Object/yaml2obj-elf-symbol-basic.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -symbols - | FileCheck %s
+# RUN: yaml2obj %s | llvm-readobj -symbols - | FileCheck %s
 !ELF
 FileHeader:
   Class: ELFCLASS64
diff --git a/llvm/test/Object/yaml2obj-elf-symbol-visibility.yaml b/llvm/test/Object/yaml2obj-elf-symbol-visibility.yaml
index 43d2b8f6fb4..82b3d48f0a3 100644
--- a/llvm/test/Object/yaml2obj-elf-symbol-visibility.yaml
+++ b/llvm/test/Object/yaml2obj-elf-symbol-visibility.yaml
@@ -1,6 +1,6 @@
-# RUN: yaml2obj -format=elf %s | llvm-readobj -symbols - | \
+# RUN: yaml2obj %s | llvm-readobj -symbols - | \
 # RUN:   FileCheck --check-prefix OBJ %s
-# RUN: yaml2obj -format=elf %s | obj2yaml - | FileCheck --check-prefix YAML %s
+# RUN: yaml2obj %s | obj2yaml - | FileCheck --check-prefix YAML %s
 
 # OBJ:      Symbol {
 # OBJ:        Name: default1 (36)
@@ -87,7 +87,7 @@
 # YAML-NEXT:       Visibility:      STV_PROTECTED
 # YAML-NEXT:       Other:           [ STO_MIPS_PIC, STO_MIPS_MICROMIPS ]
 
----
+--- !ELF
 FileHeader:
   Class:           ELFCLASS32
   Data:            ELFDATA2LSB
diff --git a/llvm/test/ObjectYAML/MachO/bind_opcode.yaml b/llvm/test/ObjectYAML/MachO/bind_opcode.yaml
index 4c010b4cd48..a83e524aef2 100644
--- a/llvm/test/ObjectYAML/MachO/bind_opcode.yaml
+++ b/llvm/test/ObjectYAML/MachO/bind_opcode.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/bogus_load_command.yaml b/llvm/test/ObjectYAML/MachO/bogus_load_command.yaml
index 4809f41df37..69c57d055cb 100644
--- a/llvm/test/ObjectYAML/MachO/bogus_load_command.yaml
+++ b/llvm/test/ObjectYAML/MachO/bogus_load_command.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/dylib_dylinker_command.yaml b/llvm/test/ObjectYAML/MachO/dylib_dylinker_command.yaml
index 5ae12d5b0bf..9184e3c5143 100644
--- a/llvm/test/ObjectYAML/MachO/dylib_dylinker_command.yaml
+++ b/llvm/test/ObjectYAML/MachO/dylib_dylinker_command.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/export_trie.yaml b/llvm/test/ObjectYAML/MachO/export_trie.yaml
index e8685c8e923..7d6513832a1 100644
--- a/llvm/test/ObjectYAML/MachO/export_trie.yaml
+++ b/llvm/test/ObjectYAML/MachO/export_trie.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/fat_macho_i386_x86_64.yaml b/llvm/test/ObjectYAML/MachO/fat_macho_i386_x86_64.yaml
index edd3338f925..75043a9de74 100644
--- a/llvm/test/ObjectYAML/MachO/fat_macho_i386_x86_64.yaml
+++ b/llvm/test/ObjectYAML/MachO/fat_macho_i386_x86_64.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !fat-mach-o
 FatHeader:       
diff --git a/llvm/test/ObjectYAML/MachO/lazy_bind_opcode.yaml b/llvm/test/ObjectYAML/MachO/lazy_bind_opcode.yaml
index d10541e2628..fafe7b206f7 100644
--- a/llvm/test/ObjectYAML/MachO/lazy_bind_opcode.yaml
+++ b/llvm/test/ObjectYAML/MachO/lazy_bind_opcode.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/load_commands.yaml b/llvm/test/ObjectYAML/MachO/load_commands.yaml
index 65405426014..5236cd0dd7a 100644
--- a/llvm/test/ObjectYAML/MachO/load_commands.yaml
+++ b/llvm/test/ObjectYAML/MachO/load_commands.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/mach_header.yaml b/llvm/test/ObjectYAML/MachO/mach_header.yaml
index 8af3187011e..f6cba123e72 100644
--- a/llvm/test/ObjectYAML/MachO/mach_header.yaml
+++ b/llvm/test/ObjectYAML/MachO/mach_header.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/mach_header_32_malformed.yaml b/llvm/test/ObjectYAML/MachO/mach_header_32_malformed.yaml
index 33946f3bde5..7b28c859f3e 100644
--- a/llvm/test/ObjectYAML/MachO/mach_header_32_malformed.yaml
+++ b/llvm/test/ObjectYAML/MachO/mach_header_32_malformed.yaml
@@ -1,4 +1,4 @@
-# RUN: not yaml2obj -format=macho %s 2>&1 | FileCheck %s
+# RUN: not yaml2obj %s 2>&1 | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/mach_header_64.yaml b/llvm/test/ObjectYAML/MachO/mach_header_64.yaml
index a76997004ea..620e09878be 100644
--- a/llvm/test/ObjectYAML/MachO/mach_header_64.yaml
+++ b/llvm/test/ObjectYAML/MachO/mach_header_64.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/out_of_order_linkedit.yaml b/llvm/test/ObjectYAML/MachO/out_of_order_linkedit.yaml
index 2d8bd24d508..5f259610386 100644
--- a/llvm/test/ObjectYAML/MachO/out_of_order_linkedit.yaml
+++ b/llvm/test/ObjectYAML/MachO/out_of_order_linkedit.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/rebase_opcode.yaml b/llvm/test/ObjectYAML/MachO/rebase_opcode.yaml
index 8a873be6e75..a50c80b385f 100644
--- a/llvm/test/ObjectYAML/MachO/rebase_opcode.yaml
+++ b/llvm/test/ObjectYAML/MachO/rebase_opcode.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/sections.yaml b/llvm/test/ObjectYAML/MachO/sections.yaml
index e1b2c2e7b5c..5da789dbdef 100644
--- a/llvm/test/ObjectYAML/MachO/sections.yaml
+++ b/llvm/test/ObjectYAML/MachO/sections.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/symtab.yaml b/llvm/test/ObjectYAML/MachO/symtab.yaml
index 7472d4462d3..b82d45bfa78 100644
--- a/llvm/test/ObjectYAML/MachO/symtab.yaml
+++ b/llvm/test/ObjectYAML/MachO/symtab.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/ObjectYAML/MachO/weak_bind_opcode.yaml b/llvm/test/ObjectYAML/MachO/weak_bind_opcode.yaml
index 6e652f46bae..a674b0e022e 100644
--- a/llvm/test/ObjectYAML/MachO/weak_bind_opcode.yaml
+++ b/llvm/test/ObjectYAML/MachO/weak_bind_opcode.yaml
@@ -1,4 +1,4 @@
-# RUN: yaml2obj -format=macho %s | obj2yaml | FileCheck %s
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
 
 --- !mach-o
 FileHeader:      
diff --git a/llvm/test/tools/llvm-ar/Inputs/coff.yaml b/llvm/test/tools/llvm-ar/Inputs/coff.yaml
index 41778d235a9..4fc1211dcf5 100644
--- a/llvm/test/tools/llvm-ar/Inputs/coff.yaml
+++ b/llvm/test/tools/llvm-ar/Inputs/coff.yaml
@@ -1,4 +1,4 @@
----
+--- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_AMD64
   Characteristics: [  ]
diff --git a/llvm/test/tools/llvm-ar/Inputs/elf.yaml b/llvm/test/tools/llvm-ar/Inputs/elf.yaml
index 28a264f7b3b..2651e68f78f 100644
--- a/llvm/test/tools/llvm-ar/Inputs/elf.yaml
+++ b/llvm/test/tools/llvm-ar/Inputs/elf.yaml
@@ -1,4 +1,4 @@
----
+--- !ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
diff --git a/llvm/test/tools/llvm-ar/default-add.test b/llvm/test/tools/llvm-ar/default-add.test
index 525db85d3a5..88719e4efce 100644
--- a/llvm/test/tools/llvm-ar/default-add.test
+++ b/llvm/test/tools/llvm-ar/default-add.test
@@ -1,5 +1,5 @@
-RUN: yaml2obj -format macho %S/Inputs/macho.yaml -o %t-macho.o
-RUN: yaml2obj -format coff %S/Inputs/coff.yaml -o %t-coff.o
+RUN: yaml2obj %S/Inputs/macho.yaml -o %t-macho.o
+RUN: yaml2obj %S/Inputs/coff.yaml -o %t-coff.o
 
 RUN: rm -f %t.ar
 RUN: llvm-ar crs %t.ar %t-macho.o
diff --git a/llvm/test/tools/llvm-ar/default-coff.test b/llvm/test/tools/llvm-ar/default-coff.test
index 7921144a428..a7ce44a23d2 100644
--- a/llvm/test/tools/llvm-ar/default-coff.test
+++ b/llvm/test/tools/llvm-ar/default-coff.test
@@ -1,4 +1,4 @@
-RUN: yaml2obj -format coff %S/Inputs/coff.yaml -o %t.obj
+RUN: yaml2obj %S/Inputs/coff.yaml -o %t.obj
 
 RUN: rm -f %t.ar
 RUN: llvm-ar crs %t.ar %t.obj
diff --git a/llvm/test/tools/llvm-ar/default-elf.test b/llvm/test/tools/llvm-ar/default-elf.test
index 216e874059e..d2d35a5e18f 100644
--- a/llvm/test/tools/llvm-ar/default-elf.test
+++ b/llvm/test/tools/llvm-ar/default-elf.test
@@ -1,4 +1,4 @@
-RUN: yaml2obj -format elf %S/Inputs/elf.yaml -o %t.o
+RUN: yaml2obj %S/Inputs/elf.yaml -o %t.o
 
 RUN: rm -f %t.ar
 RUN: llvm-ar crs %t.ar %t.o
diff --git a/llvm/test/tools/llvm-ar/default-macho.test b/llvm/test/tools/llvm-ar/default-macho.test
index ee816071c8e..a9f12758a12 100644
--- a/llvm/test/tools/llvm-ar/default-macho.test
+++ b/llvm/test/tools/llvm-ar/default-macho.test
@@ -1,4 +1,4 @@
-RUN: yaml2obj -format macho %S/Inputs/macho.yaml -o %t.o
+RUN: yaml2obj %S/Inputs/macho.yaml -o %t.o
 
 RUN: rm -f %t.ar
 RUN: llvm-ar crs %t.ar %t.o
diff --git a/llvm/test/tools/llvm-ar/override.test b/llvm/test/tools/llvm-ar/override.test
index e9aa8c1ecdc..0cbf5d85982 100644
--- a/llvm/test/tools/llvm-ar/override.test
+++ b/llvm/test/tools/llvm-ar/override.test
@@ -1,4 +1,4 @@
-RUN: yaml2obj -format macho %S/Inputs/macho.yaml -o %t.o
+RUN: yaml2obj %S/Inputs/macho.yaml -o %t.o
 
 RUN: rm -f %t.ar
 RUN: llvm-ar -format gnu crs %t.ar %t.o
diff --git a/llvm/test/tools/llvm-objdump/Inputs/file-aux-record.yaml b/llvm/test/tools/llvm-objdump/Inputs/file-aux-record.yaml
index d19afaf68a8..98e5ae64df9 100644
--- a/llvm/test/tools/llvm-objdump/Inputs/file-aux-record.yaml
+++ b/llvm/test/tools/llvm-objdump/Inputs/file-aux-record.yaml
@@ -1,3 +1,4 @@
+!COFF
 header: !Header
   Machine: IMAGE_FILE_MACHINE_I386 # (0x14c)
   Characteristics: [ IMAGE_FILE_DEBUG_STRIPPED ]
diff --git a/llvm/test/tools/llvm-readobj/Inputs/file-aux-record.yaml b/llvm/test/tools/llvm-readobj/Inputs/file-aux-record.yaml
index 89d6761a26d..2f74a9a6ef4 100644
--- a/llvm/test/tools/llvm-readobj/Inputs/file-aux-record.yaml
+++ b/llvm/test/tools/llvm-readobj/Inputs/file-aux-record.yaml
@@ -1,3 +1,4 @@
+!COFF
 header: !Header
   Machine: IMAGE_FILE_MACHINE_I386 # (0x14c)
   Characteristics: [ IMAGE_FILE_DEBUG_STRIPPED ]
diff --git a/llvm/test/tools/llvm-readobj/Inputs/file-multiple-aux-records.yaml b/llvm/test/tools/llvm-readobj/Inputs/file-multiple-aux-records.yaml
index d5b1eec878b..42946b4fafb 100644
--- a/llvm/test/tools/llvm-readobj/Inputs/file-multiple-aux-records.yaml
+++ b/llvm/test/tools/llvm-readobj/Inputs/file-multiple-aux-records.yaml
@@ -1,3 +1,4 @@
+!COFF
 header: !Header
   Machine: IMAGE_FILE_MACHINE_I386 # (0x14c)
   Characteristics: [ IMAGE_FILE_DEBUG_STRIPPED ]
diff --git a/llvm/test/tools/llvm-readobj/elf-sec-flags.test b/llvm/test/tools/llvm-readobj/elf-sec-flags.test
index 95a417a054f..842ded3e9e5 100644
--- a/llvm/test/tools/llvm-readobj/elf-sec-flags.test
+++ b/llvm/test/tools/llvm-readobj/elf-sec-flags.test
@@ -1,6 +1,6 @@
 # Check that llvm-readobj shows arch specific ELF section flags.
 
-# RUN: yaml2obj -format=elf -docnum 1 %s > %t-amdgpu.o
+# RUN: yaml2obj -docnum 1 %s > %t-amdgpu.o
 # RUN: llvm-readobj -s %t-amdgpu.o | FileCheck -check-prefix=AMD %s
 
 # AMD:      Flags [ (0x300000)
@@ -9,7 +9,7 @@
 # AMD-NEXT: ]
 
 # amdgpu.o
----
+--- !ELF
 FileHeader:
   Class:    ELFCLASS64
   Data:     ELFDATA2LSB
@@ -23,7 +23,7 @@ Sections:
     Flags:  [SHF_AMDGPU_HSA_GLOBAL, SHF_AMDGPU_HSA_READONLY]
     Size:   4
 
-# RUN: yaml2obj -format=elf -docnum 2 %s > %t-hex.o
+# RUN: yaml2obj -docnum 2 %s > %t-hex.o
 # RUN: llvm-readobj -s %t-hex.o | FileCheck -check-prefix=HEX %s
 
 # HEX:      Flags [ (0x10000000)
@@ -31,7 +31,7 @@ Sections:
 # HEX-NEXT: ]
 
 # hex.o
----
+--- !ELF
 FileHeader:
   Class:    ELFCLASS32
   Data:     ELFDATA2LSB
@@ -44,7 +44,7 @@ Sections:
     Flags:  [SHF_HEX_GPREL]
     Size:   4
 
-# RUN: yaml2obj -format=elf -docnum 3 %s > %t-mips.o
+# RUN: yaml2obj -docnum 3 %s > %t-mips.o
 # RUN: llvm-readobj -s %t-mips.o | FileCheck -check-prefix=MIPS %s
 
 # MIPS:      Flags [ (0x38000000)
@@ -54,7 +54,7 @@ Sections:
 # MIPS-NEXT: ]
 
 # mips.o
----
+--- !ELF
 FileHeader:
   Class:    ELFCLASS32
   Data:     ELFDATA2LSB
@@ -67,7 +67,7 @@ Sections:
     Flags:  [SHF_MIPS_GPREL, SHF_MIPS_MERGE, SHF_MIPS_NOSTRIP]
     Size:   4
 
-# RUN: yaml2obj -format=elf -docnum 4 %s > %t-x86_64.o
+# RUN: yaml2obj -docnum 4 %s > %t-x86_64.o
 # RUN: llvm-readobj -s %t-x86_64.o | FileCheck -check-prefix=X86_64 %s
 
 # X86_64:      Flags [ (0x10000000)
@@ -75,7 +75,7 @@ Sections:
 # X86_64-NEXT: ]
 
 # x86_64.o
----
+--- !ELF
 FileHeader:
   Class:    ELFCLASS64
   Data:     ELFDATA2LSB
diff --git a/llvm/test/tools/sanstats/elf.test b/llvm/test/tools/sanstats/elf.test
index 0b6292f82f8..91651bc3f9d 100644
--- a/llvm/test/tools/sanstats/elf.test
+++ b/llvm/test/tools/sanstats/elf.test
@@ -1,5 +1,5 @@
-# RUN: yaml2obj -format=elf %s > %t1.o
-# RUN: yaml2obj -format=elf %s > %t2.o
+# RUN: yaml2obj %s > %t1.o
+# RUN: yaml2obj %s > %t2.o
 
 # RUN: echo -ne "\x04" > %t.stats
 
@@ -39,7 +39,7 @@
 # CHECK: /tmp{{[/\\]}}f.c:2 f2 cfi-icall 12
 # CHECK: /tmp{{[/\\]}}f.c:1 f1 <unknown> 14
 
----
+--- !ELF
 FileHeader:      
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
diff --git a/llvm/test/tools/yaml2obj/missing_document_tag.yaml b/llvm/test/tools/yaml2obj/missing_document_tag.yaml
new file mode 100644
index 00000000000..3cec172d580
--- /dev/null
+++ b/llvm/test/tools/yaml2obj/missing_document_tag.yaml
@@ -0,0 +1,6 @@
+# RUN: not yaml2obj %s 2>&1 | FileCheck %s
+
+---
+DummyData:
+  foo:           0
+...
diff --git a/llvm/test/tools/yaml2obj/unsupported_document_tag.yaml b/llvm/test/tools/yaml2obj/unsupported_document_tag.yaml
new file mode 100644
index 00000000000..e73d450a9bb
--- /dev/null
+++ b/llvm/test/tools/yaml2obj/unsupported_document_tag.yaml
@@ -0,0 +1,8 @@
+# RUN: not yaml2obj %s 2>&1 | FileCheck %s
+
+--- !unsupported-tag
+DummyData:
+  foo:           0
+...
+
+#check error: YAML Object File unsupported document type tag '!unsupported-tag'!