Fix ubsan bounds check failure.

llvm-svn: 332866
2018-05-21 19:09:47 +00:00 · 2018-05-21 19:09:47 +00:00 · 2602a0d40c
parent f14e62c9a5
commit 2602a0d40c
1 changed files with 2 additions and 1 deletions
--- a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@ -365,7 +365,8 @@ bool X86AsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const {
    for (uint8_t i = 0; i < Prefixes; i++)
      OS << '\x66';
    const uint8_t Rest = ThisNopLength - Prefixes;
-    OS.write(Nops[Rest - 1], Rest);
+    if (Rest != 0)
+      OS.write(Nops[Rest - 1], Rest);
    Count -= ThisNopLength;
  } while (Count != 0);