[InstCombine] Pre-commit test for D124015

[craig.topper]

llvm/test/Transforms/InstCombine/bitcast.ll

436

test4, test5, and test6 also test OptimizeIntegerToVectorInsertions which is why I put the test here.

[spatel]

LGTM

llvm/test/Transforms/InstCombine/bitcast.ll

;
   %tmp23 = bitcast float %A to i32
   %tmp24 = zext i32 %tmp23 to i64
   %tmp25 = shl i64 %tmp24, 32
   %mask20 = or i64 %tmp25, 1109917696
   %tmp35 = bitcast i64 %mask20 to <2 x float>
   ret <2 x float> %tmp35
 }
 
+; FIXME: This test should not be optimized by OptimizeIntegerToVectorInsertions.
+; The bitcast from vector is confusing it.
+define <2 x i64> @int2vec_insertion_bitcast_from_vec(i64 %x) {
+; CHECK-LABEL: @int2vec_insertion_bitcast_from_vec(
+; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <2 x i64> <i64 poison, i64 0>, i64 [[X:%.*]], i64 0
+; CHECK-NEXT:    ret <2 x i64> [[TMP1]]
+;
+  %a = bitcast i64 %x to <8 x i8>
+  %b = zext <8 x i8> %a to <8 x i16>
+  %c = bitcast <8 x i16> %b to i128
+  %d = bitcast i128 %c to <2 x i64>
+  ret <2 x i64> %d
+}
+
 define i64 @ISPC0(i64 %in) {
 ; CHECK-LABEL: @ISPC0(
 ; CHECK-NEXT:    ret i64 0
 ;
   %out = and i64 %in, xor (i64 bitcast (<4 x i16> <i16 -1, i16 -1, i16 -1, i16 -1> to i64), i64 -1)
   ret i64 %out
 }