tree b9ff3fb15d4876aa81772ee5dba22265824a06f3
parent f65e518550a886dba50e6c4f7f2b25f0e71e60e7
author Devon Loehr <dloehr@google.com> 1719346535 -0400
committer swiftshader-scoped@luci-project-accounts.iam.gserviceaccount.com <swiftshader-scoped@luci-project-accounts.iam.gserviceaccount.com> 1719350766 +0000

Change enum values in to avoid implicit bitfield conversion

Signed values are stored using two's complement, so when a signed
value is converted to a 1-bit bitfield, it transforms the value 1
into -1, causing clang to issue a warning. See here for a more
detailed discussion: https://github.com/llvm/llvm-project/issues/53253
This warning is currently disabled in chrome (crbug.com/40234766),
but we'd like to re-enable it.

The conversion is happening with the enum values in IceIntrinsics.h.
To avoid it, we set the _T values to -1 instead of 1 at the beginning,
so there's no implicit conversion. This is rather ugly, since
intuitively we would like the "true" value to be 1, but it's the only
solution I'm aware of.

I tried several other options to force clang to treat the enum as an
unsigned value, but this causes it to change the memory layout of the
IntrinsicInfo struct, doubling its size (4 bytes -> 8 bytes).

There should be no change in program semantics, since the value was
being treated as -1 anyway -- this change just makes it explicit.

Change-Id: I9bf0259bb81677b50951755118f2492300d166a4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/73748
Tested-by: Shahbaz Youssefi <syoussefi@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@google.com>
Commit-Queue: Shahbaz Youssefi <syoussefi@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>