[llvm] [AMDGPU][True16] Legalize S16 for stores & loads in GlobalISel when True16 is enabled (PR #176963)

[Matt Arsenault via llvm-commits]

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@@ -418,6 +418,18 @@ bool AMDGPURegBankCombinerImpl::combineD16Load(MachineInstr &MI) const {
       return false;
     }
 
+    if (Load->getOpcode() == AMDGPU::G_ZEXT) {
+      SextLoad = getDefIgnoringCopies(Load->getOperand(1).getReg(), MRI);
+      if (!SextLoad || SextLoad->getOpcode() != AMDGPU::G_SEXTLOAD)
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arsenm wrote:

cast to GSExtLoad and use getMMO / getMemSize 

https://github.com/llvm/llvm-project/pull/176963