[PATCH] D122540: [X86] Fix handling of maskmovdqu in x32 differently
Kan Shengchen via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 31 18:40:04 PDT 2022
skan added inline comments.
================
Comment at: llvm/lib/Target/X86/X86InstrSSE.td:4000-4001
let ExeDomain = SSEPackedInt, SchedRW = [SchedWriteVecMoveLS.XMM.MR] in {
-let Uses = [EDI], Predicates = [HasAVX,Not64BitMode] in
+// As there is no attribute class for 64-bit and VEX, VMASKMOVDQU and
+// VMASKMOVDQU64 would have a decode conflict. Prefer VMASKMODDQU64.
+let Uses = [EDI], Predicates = [HasAVX], isAsmParserOnly = 1 in
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The comment here is not correct. The disassembler knows the mode 16-bit/32-bit/64-bit when decoding an instruction, and VEX prefix does change the instruction context. I believe the conflict is b/c the only difference between the encodings of VMASKMOVDQU and VMASKMOVDQU64 is a address-size prefix.
Repository:
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CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D122540/new/
https://reviews.llvm.org/D122540
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