[llvm] [AMDGPU] Ensure positive InstOffset for buffer operations (PR #145504)

[Shilei Tian via llvm-commits]

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@@ -4547,6 +4548,16 @@ bool AMDGPUAsmParser::validateSMEMOffset(const MCInst &Inst,
 
   uint64_t Offset = Op.getImm();
   bool IsBuffer = AMDGPU::getSMEMIsBuffer(Opcode);
+  // GFX12+ S_BUFFER_*: InstOffset is signed 24, but must be positive
+  if (isGFX12Plus() && IsBuffer) {
+    const unsigned OffsetSize = 24;
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shiltian wrote:

nit:
```suggestion
    constexpr const unsigned OffsetSize = 24;
```

https://github.com/llvm/llvm-project/pull/145504