Make TargetLowering::getTypeConversion more resilient against odd illegal MVTs.

- An MVT can become an EVT when being split (e.g. v2i8 -> v1i8, the latter doesn't exist)
- Return the scalar value when an MVT is scalarized (v1i64 -> i64)

Fixes PR14639ff.

llvm-svn: 170546

llvm/include/llvm/Target/TargetLowering.h

@@ -2005,8 +2005,11 @@ public:
          && "Promote may not follow Expand or Promote");
 
       if (LA == TypeSplitVector)
-        NVT = MVT::getVectorVT(SVT.getVectorElementType(),
+        return LegalizeKind(LA, EVT::getVectorVT(Context,
-                               SVT.getVectorNumElements() / 2);
+                                                 SVT.getVectorElementType(),
+                                                 SVT.getVectorNumElements()/2));
+      if (LA == TypeScalarizeVector)
+        return LegalizeKind(LA, SVT.getVectorElementType());
       return LegalizeKind(LA, NVT);
     }
 

llvm/test/Transforms/LoopVectorize/X86/no-vector.ll

@@ -0,0 +1,22 @@
+; RUN: opt -S -mtriple=i386-unknown-freebsd -mcpu=i486 -loop-vectorize < %s
+
+define i32 @PR14639(i8* nocapture %s, i32 %len) nounwind {
+entry:
+  %cmp4 = icmp sgt i32 %len, 0
+  br i1 %cmp4, label %for.body, label %for.end
+
+for.body:                                         ; preds = %entry, %for.body
+  %i.06 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %r.05 = phi i32 [ %xor, %for.body ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i8* %s, i32 %i.06
+  %0 = load i8* %arrayidx, align 1
+  %conv = sext i8 %0 to i32
+  %xor = xor i32 %conv, %r.05
+  %inc = add nsw i32 %i.06, 1
+  %exitcond = icmp eq i32 %inc, %len
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body, %entry
+  %r.0.lcssa = phi i32 [ 0, %entry ], [ %xor, %for.body ]
+  ret i32 %r.0.lcssa
+}