[llvm] MIPS: Support '%w' token in inline asm template for MSA (PR #91920)

[Jessica Clarke via llvm-commits]

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@@ -565,12 +565,27 @@ bool MipsAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
       }
       break;
     }
-    case 'w':
-      // Print MSA registers for the 'f' constraint
-      // In LLVM, the 'w' modifier doesn't need to do anything.
-      // We can just call printOperand as normal.
+    case 'w': {
+      // Support to use MSA instructions on FPR.
+      // double a, b, c;
+      // asm volatile ("fmadd.d %w0, %w1, %w2" : "+f"(a) : "f"(b), "f"(c))
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jrtc27 wrote:

Clearly if you don't implement a feature that feature doesn't work. My point is that you don't need a C snippet to illustrate what is going on here, especially if you simplify the code as I suggested. Otherwise the backend would be full of random bits of C in comments.

https://github.com/llvm/llvm-project/pull/91920