[Mono-dev] issue with mini_type_is_hfa

Bill Seurer seurer at linux.vnet.ibm.com
Fri Sep 18 15:56:50 UTC 2015

I have been working on fixing things for the new ABI v2 for power and 
ran into a problem using mini_type_is_hfa in mini-codegen.c.

The problematic code is:

			// FIXME: Nested float structs are aligned to 8 bytes
			if (ftype->type == MONO_TYPE_R4)
				return FALSE;

So if a nested structure has a float field mini_type_is_hfa returns 
false which breaks the v2 ABI.

Example structure from my test case:

	// This structure has nested structures within it but they are
	//  homogenous and thus should still use the special rules.
	public struct float4_nested1 {
		public float f1;
	public struct float4_nested2 {
		public float f4;
	public struct float4_nested {
		public float4_nested1 nested1;
		public float f2,f3;
		public float4_nested2 nested2;

I am not sure what the comment is referring to because this structure 
appears to be laid out as 4 floats in a row with no padding.  I printed 
out some info for the class:

klass: Test_float.float4_nested
size: 16
mbr_cnt=4, mbr_size=4

If I remove those two lines from mini_type_is_hfa then it works as 
expected and the test case succeeds.


-Bill Seurer

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