[clang] [mlir] [CIR] Honor the Direct coercion offset in x86_64 callconv lowering (PR #220724)

[Andy Kaylor via cfe-commits]

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@@ -44,9 +41,17 @@ struct s3_0 {};
 struct s3_1 { struct s3_0 a; long b; };
 void f3(struct s3_1 x) {}
 
+// The empty member owns eightbyte 0, so the live long is the second eightbyte
+// and the coercion starts at byte 8.
 // CIR-LABEL: cir.func {{.*}} @_Z2f34s3_1
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andykaylor wrote:

CIR checks?

https://github.com/llvm/llvm-project/pull/220724