Replace codeversion with feature flags. #198
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The codeversion field is a little too heavy weight and makes it difficult to support parallel compiler branches. We ideally need a major/minor system or a feature flag set. In this patch we opt for feature flags since they also make it easier to develop experimental features. The codeversion has been bumped to 13 for this patch. Older VMs will reject binaries with this codeversion. Newer compilers will still emit codeversion=11 by default. The feature bits will still be present, but set to zero. This is legal since the file format requires ignoring extra data between the header and code blob, and indeed all old VMs follow this rule.
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The codeversion field is a little too heavy weight and makes it difficult to support parallel
compiler branches. We ideally need a major/minor system or a feature flag set. In this patch
we opt for feature flags since they also make it easier to develop experimental features.
The version has been bumped to 13 for this patch.
Newer compilers will still emit codeversion=11 by default. The feature bits will still be present,
but set to zero. This is legal since the file format requires ignoring extra data between the
header and code blob, and indeed all old VMs follow this rule.