[cfe-commits] [PATCH] PR12094: set alignment of memory builtins

[Jay Foad]

http://llvm.org/bugs/show_bug.cgi?id=12094

The attached patch:

- Makes CGBuiltin.cpp's helper function GetPointeeAlignment into a
proper member of CodeGenFunction and splits it into two:
-- GetPointeeAlignment, which returns alignment as an unsigned, and
-- GetPointeeAlignmentValue, which wraps the result in an llvm::Value
for the convenience of generating ARM NEON intrinsics.

- Uses GetPointeeAlignment to set a sensible alignment on all memory
intrinsics (memcpy, memset etc.) instead of the conservative default
of 1.

Tested with "make check-all". Unfortunately I can only test on x86_64,
where alignment doesn't make much difference. Can anyone test it on
what GCC would call a STRICT_ALIGNMENT target for me?

I also tried compiling sqlite3.c (from test-suite) with clang -O2,
before and after my changes. The only differences were a handful of
calls to memcpy replaced with "rep;movsq", which seems good.

Thanks,
Jay.
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