We are using the Linaro prebuilt binary 2013.03 toolchain.
We have a program that does a memcpy of 6 bytes and the source and
destination pointers are both 6 byte arrays (through multiple levels of
struct & union etc).
At -O2 we get the memcpy inlined.
The code area in question is:
22840: f8b7 2054 ldrh.w r2, [r7, #84] ; 0x54
22844: f853 1d12 ldr.w r1, [r3, #-18]!
22848: f042 0202 orr.w r2, r2, #2
2284c: 889b ldrh r3, [r3, #4]
2284e: b292 uxth r2, r2
->22850: f8c7 101a str.w r1, [r7, #26]
22854: f8a7 2054 strh.w r2, [r7, #84] ; 0x54
22858: 83fb strh r3, [r7, #30]
2285a: f8da 3000 ldr.w r3, [sl]
And we get an alignment fault at the str.w marked above.
Looking at the types involved and their location in the containing
structures I don't see how the compiler could think that the destination
was word aligned
(I believe it is guaranteed that dest % 8 == 6)
There are no -march -mcpu or -mtune params passed to the compiler. The
code is running in user space on a A15.
Basic question before we look further:
Is the compiler assuming that cp15 SCTLR.A is 0 so that it is free to
generate unaligned loads and stores?
If the answer to the above is "no" we can isolate the code more and
bring it back to the list.
Thanks,
Bill
---------------------------------------
William A. Mills
Chief Technologist, Open Solutions, SDO
Texas Instruments, Inc.
20450 Century Blvd
Germantown MD 20878
240-643-0836
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