tree 2484574661da4725ba920ee67696203345294f5c
parent 37ced5a571066c11548c672f354c6091f5903991
author Lucas Prates <lucas.prates@arm.com> 1585310029 +0000
committer Lucas Prates <lucas.prates@arm.com> 1585824920 +0100

[Clang][CodeGen] Fixing mismatch between memory layout and const expressions for oversized bitfields

Summary:
The construction of constants for structs/unions was conflicting the
expected memory layout for over-sized bit-fields. When building the
necessary bits for those fields, clang was ignoring the size information
computed for the struct/union memory layout and using the original data
from the AST's FieldDecl information. This caused an issue in big-endian
targets, where the field's contant was incorrectly misplaced due to
endian calculations.

This patch aims to separate the constant value from the necessary
padding bits, using the proper size information for each one of them.
With this, the layout of constants for over-sized bit-fields matches the
ABI requirements.

Reviewers: rsmith, eli.friedman, efriedma

Reviewed By: efriedma

Subscribers: efriedma, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D77048