tree fcd862c37affd38c8490cb9acdb1dff8c2fb3dfc
parent 5059719664731ff36ca52cc20fa805c44e9ebdd6
author Nicolas Capens <capn@google.com> 1626206184 -0400
committer Nicolas Capens <nicolascapens@google.com> 1626726552 +0000

Fix RequiredStackAlignment initialization

sizeof(Traits::WordType) evaluates to obtaining the size of the numeric
value of the IceType_i32 or IceType_i64 enum. Because enums default to
being constants with an underlying type of 'int', this becomes 4 for
both the x86-32 and x86-64 backends, while 8 was intended for the
latter.

A misaligned stack may have a significant performance impact.

Note that an even greater stack alignment might be required, as both the
Microsoft and System V x64 ABI require 16-byte alignment. This change
only addresses the obvious semantics bug.

Bug: b/193550986
Change-Id: If33c0a10d73c50bfb1bbc25f16acb97b3575e27a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/55809
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Sean Risser <srisser@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>