[llvm] [PowerPC]redesign the target flags (PR #69695)

[Chen Zheng via llvm-commits]

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@@ -102,79 +102,99 @@ class ModulePass;
     // PPC Specific MachineOperand flags.
     MO_NO_FLAG,
 
+    /// On PPC, the 12 bits are not enough for all target operand flags.
+    /// Treat all PPC target flags as direct flags. This also means we can not
+    /// use a bitmask flag, so if one operand has two or more flags, a fake
+    /// combination flag must be created. See example MO_GOT_TPREL_PCREL_FLAG.
+
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chenzheng1030 wrote:

For `orthogonal masks`, do you mean bitmask flag? Actually 12 bits are for both "bitmask" flag and "direct flag". Before the change, we have 8 orthogonal mask and 4 bit for direct mask.

https://github.com/llvm/llvm-project/pull/69695