[llvm] [AMDGPU][True16] Legalize S16 for G_STORE/G_LOAD in GlobalISel when True16 is enabled (PR #176963)

[Petar Avramovic 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)
+        return false;
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petar-avramovic wrote:

should use mi_match and merge with G_AMDGPU_LOAD_D16_LO_I8 below.
But none of the tests are affected by G_AMDGPU_LOAD_D16_LO_I8 match below. Can you try adding check line for some older target without true 16, to confirm if we still need below matchers, if there is really nothing just delete
 

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