UNINIT reports on libjpeg_turbo [SSE2 instructions]

_From [timurrrr@google.com](https://code.google.com/u/timurrrr@google.com/) on August 04, 2011 10:49:28_

http://build.chromium.org/p/chromium.fyi/builders/Windows%20Tests%20%28DrMemory%29/builds/4691/steps/memory%20test%3A%20unit_1/logs/stdio UNINITIALIZED READ: reading 0x407e0738-0x407e0740 8 byte(s) within 0x407e0730-0x407e0740
#1 jsimd_ycc_extbgrx_convert_sse2
#2 jsimd_ycc_rgb_convert third_party\libjpeg_turbo\simd\jsimd_i386.c:199
#3 jsimd_ycc_rgb_convert third_party\libjpeg_turbo\simd\jsimd_i386.c:199
#4 sep_upsample third_party\libjpeg_turbo\jdsample.c:133
#5 process_data_context_main third_party\libjpeg_turbo\jdmainct.c:432
#6 chromium_jpeg_read_scanlines third_party\libjpeg_turbo\jdapistd.c:173
#7 gfx::JPEGCodec::Decode ui\gfx\codec\jpeg_codec.cc:539
#8 gfx::JPEGCodec::Decode ui\gfx\codec\jpeg_codec.cc:594
#9 history::ExpireHistoryTest::AddExampleData chrome\browser\history\expire_history_backend_unittest.cc:232
#10 history::ExpireHistoryTest_ArchiveHistoryBeforeStarred_Test::TestBody chrome\browser\history\expire_history_backend_unittest.cc:779
// the instruction in the global.PID.log during a local run is "movdqa (%esi) -> %xmm5"
// TODO: find out where does it propagate from. [ issue #170 would help here]

If "set JSIMD_FORCEMMX=1" to switch SSE2 implementation with MMX, the same test has 0 uninit reports.

SSE2 deals with floating-point operands and we require all bits to be set for FP registers [xref issue #471 ], that looks like the reason for the reports.

FTR, jsimd_h2v2_fancy_upsample_sse2 assembly is codesearch'able.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=540_