[llvm] [AMDGPU] Add mark last scratch load pass (PR #75512)

[Matt Arsenault via llvm-commits]

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@@ -1658,7 +1658,9 @@ void SIRegisterInfo::buildSpillLoadStore(
       MIB.addReg(SOffset, SOffsetRegState);
     }
 
-    int64_t CPol = AMDGPU::isGFX12Plus(ST) && LastUse ? AMDGPU::CPol::TH_LU : 0;
+    assert((!LastUse || AMDGPU::isGFX12Plus(ST)) &&
+           "last_use operand exists only on GFX12+");
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arsenm wrote:

verifier should probably be checking this instead 

https://github.com/llvm/llvm-project/pull/75512