Bug 40410

Summary:

Avoid increasing required alignment of target type warning on ARM

Product:

WebKit

Reporter:

Gabor Loki <loki>

Component:

JavaScriptCore

Assignee:

Gabor Loki <loki>

Status:

RESOLVED DUPLICATE

Severity:

Minor

Priority:

Version:

528+ (Nightly build)

Hardware:

All

OS:

All

Attachments:

Description	Flags
Avoid increasing required alignment of target type warning on ARM (part 1)	none
Avoid increasing required alignment of target type warning on ARM (part 2)	none
Avoid increasing required alignment of target type warning on ARM (part 3)	none
Avoid increasing required alignment of target type warning on ARM (part 4)	none

Gabor Loki

Reported 2010-06-10 02:17:41 PDT

The reinterpret_cast<Type1*>([pointer to Type2]) expressions - where sizeof(Type1) > sizeof(Type2) - cause the following warning on ARM: increases required alignment of target type warnings. An extra static_cast<void*> cast can mute the compiler, eg.: reinterpret_cast<Type1*>(static_cast<void*>([pointer to Type2])). I am going to upload several patches to fix these warnings.

Attachments
Avoid increasing required alignment of target type warning on ARM (part 1) (2.83 KB, patch) 2010-06-10 02:45 PDT, Gabor Loki	no flags	Details Formatted Diff Diff
Avoid increasing required alignment of target type warning on ARM (part 2) (2.74 KB, patch) 2010-06-10 03:53 PDT, Gabor Loki	no flags	Details Formatted Diff Diff
Avoid increasing required alignment of target type warning on ARM (part 3) (7.66 KB, patch) 2010-06-10 04:31 PDT, Gabor Loki	no flags	Details Formatted Diff Diff
Avoid increasing required alignment of target type warning on ARM (part 4) (2.04 KB, patch) 2010-06-10 05:11 PDT, Gabor Loki	no flags	Details Formatted Diff Diff
View All Add attachment proposed patch, testcase, etc.

Gabor Loki

Comment 1 2010-06-10 02:45:52 PDT

Created attachment 58346 [details] Avoid increasing required alignment of target type warning on ARM (part 1) Each MacroAssembler back-end knows well if a natural alignment is required or not. So, leave them to handle the alignment. An extra ASSERT for alignment check can cause a false positive error on those architectures where an unaligned data access is available. For example on x86: ASSERT(!(static_cast<unsigned int>(&m_buffer[m_size]) % WTF_ALIGN_OF(int64_t))).

Gabor Loki

Comment 2 2010-06-10 03:53:39 PDT

Created attachment 58357 [details] Avoid increasing required alignment of target type warning on ARM (part 2) Fix the increasing required alignment of target type warnings in ARMAssembler.

Gabor Loki

Comment 3 2010-06-10 04:31:25 PDT

Created attachment 58362 [details] Avoid increasing required alignment of target type warning on ARM (part 3) All static_cast can be safely done. Each data is aligned to target type.

Gabor Loki

Comment 4 2010-06-10 05:11:53 PDT

Created attachment 58365 [details] Avoid increasing required alignment of target type warning on ARM (part 4) Qt specific fix for the alignment problem.

Gabor Loki

Comment 5 2010-07-15 05:58:20 PDT

*** This bug has been marked as a duplicate of bug 38045 ***

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