[clang] [CIR] Accept __int128 in x86_64 calling-convention lowering (PR #211142)

[Andy Kaylor via cfe-commits]

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@@ -48,4 +53,20 @@ module attributes {
   }
 
   // CHECK: cir.func{{.*}} @take_noregs(%arg0: !cir.ptr<!rec_NoRegs> {llvm.align = 4 : i64, llvm.byref = !rec_NoRegs})
+
+  // A struct containing an __int128 spans more than two eightbytes, so it does
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andykaylor wrote:

This isn't quite true. If the __int128 is the only member of the structure. In that case, the structure would be coerced. It might be worth having a test case for that.

https://github.com/llvm/llvm-project/pull/211142