[PATCH] D34454: SwiftAggregateLowering: Use type alloc size to determine the size of types

[Arnold Schwaighofer via Phabricator via cfe-commits]

aschwaighofer created this revision.

The layout must be compatible with the input layout, offsets are defined in
terms of offsets within a packed struct which are computed in terms of the alloc
size of a type.

Using the store size we would insert padding for the following type for example:

struct {

  int3 v;
  long long l;

} __attribute((packed))

On x86-64 int3 is padded to int4 alignment. The swiftcc type would be
<{ <3 x float>, [4 x i8], i64 }> which is not compatible with <{ <3 x float>, i64 }>.

The latter has i64 at offset 16 and the former at offset 20.

rdar://32618125


https://reviews.llvm.org/D34454

Files:
  lib/CodeGen/SwiftCallingConv.cpp
  test/CodeGen/64bit-swiftcall.c
  test/CodeGen/windows-swiftcall.c

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