[AMDGPU] Reserve ELF code

[t-tye]

Summary

Reserve AMD GPU ELF machine code 0x040.

Minor AMDGPUUsage format consistency change.

[kzhuravl]

probably update the title to reflect there is more than one change in the commit?

llvm/include/llvm/BinaryFormat/ELF.h

737

move this to line 736. make line 737 empty.

[kzhuravl]

you also should add reserved number to docs.

[t-tye]

Address review comments.

[t-tye]

Address review comments.

[kzhuravl]

Thanks.

llvm/include/llvm/BinaryFormat/ELF.h

737

move this to line 736. make line 737 empty.

llvm/docs/AMDGPUUsage.rst

.. table:: AMDGPU ``EF_AMDGPU_MACH`` Values
      ``EF_AMDGPU_MACH_AMDGCN_GFX1032``    0x038      ``gfx1032``
      ``EF_AMDGPU_MACH_AMDGCN_GFX1033``    0x039      ``gfx1033``
      ``EF_AMDGPU_MACH_AMDGCN_GFX602``     0x03a      ``gfx602``
      ``EF_AMDGPU_MACH_AMDGCN_GFX705``     0x03b      ``gfx705``
      ``EF_AMDGPU_MACH_AMDGCN_GFX805``     0x03c      ``gfx805``
      *reserved*                           0x03d      Reserved.
      *reserved*                           0x03e      Reserved.
      ``EF_AMDGPU_MACH_AMDGCN_GFX90A``     0x03f      ``gfx90a``
+     *reserved*                           0x040      Reserved.
      ==================================== ========== =============================
 
 Sections
 --------
 
 An AMDGPU target ELF code object has the standard ELF sections which include:
 
   .. table:: AMDGPU ELF Sections
23:15   9 bits  GRANULATED_LDS_SIZE             Must be 0.
                                                      directly to
                                                      ``COMPUTE_PGM_RSRC2.LDS_SIZE``.
 
                                                      Amount of group segment
                                                      (LDS) to allocate for each
                                                      work-group. Granularity is
                                                      device specific:
 
-                                                     GFX6:
+                                                     GFX6
                                                        roundup(lds-size / (64 * 4))
-                                                     GFX7-GFX10:
+                                                     GFX7-GFX10
                                                        roundup(lds-size / (128 * 4))
 
      24      1 bit   ENABLE_EXCEPTION_IEEE_754_FP    Wavefront starts execution
                      _INVALID_OPERATION              with specified exceptions
                                                      enabled.
 
                                                      Used by CP to set up
                                                      ``COMPUTE_PGM_RSRC2.EXCP_EN``

llvm/include/llvm/BinaryFormat/ELF.h

enum : unsigned {
   EF_AMDGPU_MACH_AMDGCN_GFX1032       = 0x038,
   EF_AMDGPU_MACH_AMDGCN_GFX1033       = 0x039,
   EF_AMDGPU_MACH_AMDGCN_GFX602        = 0x03a,
   EF_AMDGPU_MACH_AMDGCN_GFX705        = 0x03b,
   EF_AMDGPU_MACH_AMDGCN_GFX805        = 0x03c,
   EF_AMDGPU_MACH_AMDGCN_RESERVED_0X3D = 0x03d,
   EF_AMDGPU_MACH_AMDGCN_RESERVED_0X3E = 0x03e,
   EF_AMDGPU_MACH_AMDGCN_GFX90A        = 0x03f,
+  EF_AMDGPU_MACH_AMDGCN_RESERVED_0X40 = 0x040,
 
   // First/last AMDGCN-based processors.
   EF_AMDGPU_MACH_AMDGCN_FIRST = EF_AMDGPU_MACH_AMDGCN_GFX600,
   EF_AMDGPU_MACH_AMDGCN_LAST = EF_AMDGPU_MACH_AMDGCN_GFX90A,
 
   // Indicates if the "xnack" target feature is enabled for all code contained
   // in the object.
   EF_AMDGPU_XNACK = 0x100,
   // Indicates if the "sram-ecc" target feature is enabled for all code