[llvm] [clang] [clang-tools-extra] [ISel] Add pattern matching for depositing subreg value (PR #75978)

[David Li via cfe-commits]

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@@ -561,6 +561,16 @@ def MOV64rm : RI<0x8B, MRMSrcMem, (outs GR64:$dst), (ins i64mem:$src),
                  [(set GR64:$dst, (load addr:$src))]>;
 }
 
+def : Pat<(or (and GR64:$dst, -256), 
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david-xl wrote:

Sorry I misunderstood. Fixed now.

Also updated the test. Note that sub16_32 case does not yet produce the optimized code for i386 because the pattern change (due to arg passing).

https://github.com/llvm/llvm-project/pull/75978