[llvm] r298957 - [AVX-512] Punt on fast-isel of truncates to i1 when AVX512 is enabled.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Tue Mar 28 18:20:37 2017
New Revision: 298957

URL: http://llvm.org/viewvc/llvm-project?rev=298957&view=rev
Log:
[AVX-512] Punt on fast-isel of truncates to i1 when AVX512 is enabled.

We should be masking the value and emitting a register copy like we do in non-fast isel. Instead we were just updating the value map and emitting nothing.

After r298928 we started seeing cases where we would create a copy from GR8 to GR32 because the source register in a VK1 to GR32 copy was replaced by the GR8 going into a truncate.

This fixes PR32451.


Modified:
    llvm/trunk/lib/Target/X86/X86FastISel.cpp

Modified: llvm/trunk/lib/Target/X86/X86FastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FastISel.cpp?rev=298957&r1=298956&r2=298957&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FastISel.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FastISel.cpp Tue Mar 28 18:20:37 2017
@@ -2512,7 +2512,8 @@ bool X86FastISel::X86SelectTrunc(const I
   EVT DstVT = TLI.getValueType(DL, I->getType());
 
   // This code only handles truncation to byte.
-  if (DstVT != MVT::i8 && DstVT != MVT::i1)
+  // TODO: Support truncate to i1 with AVX512.
+  if (DstVT != MVT::i8 && (DstVT != MVT::i1 || Subtarget->hasAVX512()))
     return false;
   if (!TLI.isTypeLegal(SrcVT))
     return false;