[llvm] [AMDGPU] si-peephole-sdwa: Disable V_CNDMASK_B32 conversion with sext (PR #140760)

[Frederik Harwath via llvm-commits]

================
@@ -430,6 +430,13 @@ bool SDWASrcOperand::convertToSDWA(MachineInstr &MI, const SIInstrInfo *TII) {
   case AMDGPU::V_CVT_PK_F32_BF8_sdwa:
     // Does not support input modifiers: noabs, noneg, nosext.
     return false;
+  case AMDGPU::V_CNDMASK_B32_sdwa:
+    // FIXME SISrcMods uses the same bitmask for SEXT and NEG
----------------
frederik-h wrote:

I have extended the comment.

https://github.com/llvm/llvm-project/pull/140760