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-rw-r--r--llvm/lib/Target/X86/X86InstrInfo.cpp6
1 files changed, 6 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 65f8b74d95c..88e454aa0cf 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -657,6 +657,12 @@ X86InstrInfo::X86InstrInfo(X86Subtarget &STI)
{ X86::VTESTPSYrr, X86::VTESTPSYrm, 0 },
// AVX2 foldable instructions
+
+ // VBROADCASTS{SD}rr register instructions were an AVX2 addition while the
+ // VBROADCASTS{SD}rm memory instructions were available from AVX1.
+ // TB_NO_REVERSE prevents unfolding from introducing an illegal instruction
+ // on AVX1 targets. The VPBROADCAST instructions are all AVX2 instructions
+ // so they don't need an equivalent limitation.
{ X86::VBROADCASTSSrr, X86::VBROADCASTSSrm, TB_NO_REVERSE },
{ X86::VBROADCASTSSYrr, X86::VBROADCASTSSYrm, TB_NO_REVERSE },
{ X86::VBROADCASTSDYrr, X86::VBROADCASTSDYrm, TB_NO_REVERSE },
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