X86: deduplicate V[SZ]EXT_MOVL and V[SZ]EXT nodes

I believe VZEXT_MOVL means "zero all vector elements except the first" (and
should have identical input & output types) whereas VZEXT means "zero extend
each element of a vector (discarding higher elements if necessary)".

For example:
    (v4i32 (vzext (v16i8 ...)))

should zero extend the low 4 bytes of the incoming vector to 32-bits,
discarding higher bytes.

However, somewhere in the past, these two concepts had become confused, even
leading to a nonsensical VSEXT_MOVL.

This re-merges the nodes where appropriate (all VSEXT_MOVL -> VSEXT, VZEXT_MOVL
-> VZEXT when it's an actual extension).

rdar://problem/15981990

llvm-svn: 200918

1 files changed, 1 insertions, 4 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.h b/llvm/lib/Target/X86/X86ISelLowering.h
index a8939a25955..5d00e26e7c2 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.h
+++ b/llvm/lib/Target/X86/X86ISelLowering.h
@@ -245,12 +245,9 @@ namespace llvm {
       /// the list of operands.
       TC_RETURN,
 
-      // VZEXT_MOVL - Vector move low and zero extend.
+      // VZEXT_MOVL - Vector move to low scalar and zero higher vector elements.
       VZEXT_MOVL,
 
-      // VSEXT_MOVL - Vector move low and sign extend.
-      VSEXT_MOVL,
-
       // VZEXT - Vector integer zero-extend.
       VZEXT,