PATCH for PR18045 (X86 inst selection failure)
stpworld at narod.ru
Fri Dec 13 05:31:39 PST 2013
Please find fix + test-case in attachment.
Short description of PR18045 issue:
For X86 machines with sse < sse4.1 we got failures for some
particular load/store vector sequences:
$ clang-trunk -m32 -O2 test-case.c
fatal error: error in backend: Cannot select: 0x4200920: v4i32,ch = load
0x41dcb10<LD16[getelementptr inbounds ([4 x i32]* @e, i32 0, i32
0x4205850: i32 = X86ISD::Wrapper 0x41d5490 [ORD=26] [ID=43]
0x41d5490: i32 = TargetGlobalAddress<[4 x i32]* @e> 0 [ORD=26] [ID=23]
0x41dcb10: i32 = undef [ID=2]
The reason is that EltsFromConsecutiveLoads could emit such load
instruction both before and after legalize stage. Though this
instruction is not legal for machines with SSSE3 and lower.
The fix: In EltsFromConsecutiveLoads, if we have passed legalize stage,
we check whether nodes it emits are legal.
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