[llvm] [AMDGPU] Don't form sext/abs/neg fp8 cvt (PR #83843)

[Matt Arsenault via llvm-commits]

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@@ -4707,6 +4707,20 @@ bool SIInstrInfo::verifyInstruction(const MachineInstr &MI,
       }
     }
 
+    if (Opcode == AMDGPU::V_CVT_F32_FP8_sdwa ||
+        Opcode == AMDGPU::V_CVT_F32_BF8_sdwa ||
+        Opcode == AMDGPU::V_CVT_PK_F32_FP8_sdwa ||
+        Opcode == AMDGPU::V_CVT_PK_F32_BF8_sdwa) {
+      const MachineOperand *Src0ModsMO =
+          getNamedOperand(MI, AMDGPU::OpName::src0_modifiers);
+      unsigned Mods = Src0ModsMO->getImm();
+      if (Mods & SISrcMods::ABS || Mods & SISrcMods::NEG ||
+          Mods & SISrcMods::SEXT) {
+        ErrInfo = "sext, abs and neg are not allowed on this instruction";
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arsenm wrote:

Missing verifier test 

https://github.com/llvm/llvm-project/pull/83843