tree f08a04e1bb8723ec0766ddf4257e5be30600c498
parent f14f6c46e4bec7734a6d998bf04961578f34641f
author Antonio Maiorano <amaiorano@google.com> 1604547279 -0500
committer Antonio Maiorano <amaiorano@google.com> 1604606351 +0000

Subzero: fix invalid arg access on Windows x86 for split variables

See the first bug I fixed related to this: 7fefd4833b96e0eea1478d4a3751bb7662504bfc.

That bug fix ensured that arguments are accessed relative to 'ebp'
rather than 'esp' on Windows x86. However, when an arg Variable gets
split (see LocalVariableSplitter), the new Variable that's linked to the
original arg Variable must also use 'ebp' in the same way. This is now
fixed by making sure to set its "isArg" state to match that of the
"linked stack root" Variable at the same time as we set its
"stackOffset" in the same way. Thus, when stackVarToAsmOperand is called
during emitIAS, split Variables are properly addressed using the correct
frame pointer.

See the detailed design doc:
https://docs.google.com/document/d/1IBsWg2V9_arWGYkpuwlKdne4lkA6XwSQ8fp99l8BmnA

This fixes the intermittent crash reported here:
https://bugs.chromium.org/p/angleproject/issues/detail?id=4482#c15

Bug: angleproject:4482
Change-Id: Ibc089f3a5b9a44f40f130a3db8656011212d2983
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/50008
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>