[llvm] [AMDGPU][GlobalISel] Add RegBankLegalize support for G_FPEXT (PR #171483)

[Matt Arsenault via llvm-commits]

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@@ -976,6 +976,13 @@ RegBankLegalizeRules::RegBankLegalizeRules(const GCNSubtarget &_ST,
       .Any({{UniS32, S32}, {{Sgpr32}, {Sgpr32}}}, hasSALUFloat)
       .Any({{UniS32, S32}, {{UniInVgprS32}, {Vgpr32}}}, !hasSALUFloat);
 
+  addRulesForGOpcs({G_FPEXT})
+      .Any({{UniS32, S16}, {{Sgpr32}, {Sgpr16}}}, hasSALUFloat)
+      .Any({{UniS32, S16}, {{UniInVgprS32}, {Vgpr16}}}, !hasSALUFloat)
+      .Any({{DivS32, S16}, {{Vgpr32}, {Vgpr16}}})
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arsenm wrote:

The commmon cases should probably be ordered first? 

https://github.com/llvm/llvm-project/pull/171483