[LV] Peek through bitcasts when performing CSE

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -2642,8 +2642,8 @@ namespace {
 
 struct CSEDenseMapInfo {
   static bool canHandle(const Instruction *I) {
-    return isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||
-           isa<ShuffleVectorInst>(I) || isa<GetElementPtrInst>(I);
+    return isa<InsertElementInst, ExtractElementInst, ShuffleVectorInst,
+               GetElementPtrInst, BitCastInst>(I);
   }
 
   static inline Instruction *getEmptyKey() {

llvm/test/Transforms/LoopVectorize/cse-bitcast.ll

@@ -0,0 +1,74 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals none --filter-out-after "^scalar.ph" --version 5
+; RUN: opt %s -passes=loop-vectorize -force-vector-width=4 -force-vector-interleave=2 -enable-interleaved-mem-accesses=true -S | FileCheck %s
+
+define void @cse_bitcast(i16 %val, half %fval, ptr %p, i64 %n) {
+; CHECK-LABEL: define void @cse_bitcast(
+; CHECK-SAME: i16 [[VAL:%.*]], half [[FVAL:%.*]], ptr [[P:%.*]], i64 [[N:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], 8
+; CHECK-NEXT:    br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_SCEVCHECK:.*]]
+; CHECK:       [[VECTOR_SCEVCHECK]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = add i64 [[N]], -1
+; CHECK-NEXT:    [[MUL:%.*]] = call { i64, i1 } @llvm.umul.with.overflow.i64(i64 4, i64 [[TMP0]])
+; CHECK-NEXT:    [[MUL_RESULT:%.*]] = extractvalue { i64, i1 } [[MUL]], 0
+; CHECK-NEXT:    [[MUL_OVERFLOW:%.*]] = extractvalue { i64, i1 } [[MUL]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = sub i64 0, [[MUL_RESULT]]
+; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr i8, ptr [[P]], i64 [[MUL_RESULT]]
+; CHECK-NEXT:    [[TMP3:%.*]] = icmp ult ptr [[TMP2]], [[P]]
+; CHECK-NEXT:    [[TMP4:%.*]] = or i1 [[TMP3]], [[MUL_OVERFLOW]]
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, ptr [[P]], i64 2
+; CHECK-NEXT:    [[MUL1:%.*]] = call { i64, i1 } @llvm.umul.with.overflow.i64(i64 4, i64 [[TMP0]])
+; CHECK-NEXT:    [[MUL_RESULT2:%.*]] = extractvalue { i64, i1 } [[MUL1]], 0
+; CHECK-NEXT:    [[MUL_OVERFLOW3:%.*]] = extractvalue { i64, i1 } [[MUL1]], 1
+; CHECK-NEXT:    [[TMP5:%.*]] = sub i64 0, [[MUL_RESULT2]]
+; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr i8, ptr [[SCEVGEP]], i64 [[MUL_RESULT2]]
+; CHECK-NEXT:    [[TMP7:%.*]] = icmp ult ptr [[TMP6]], [[SCEVGEP]]
+; CHECK-NEXT:    [[TMP8:%.*]] = or i1 [[TMP7]], [[MUL_OVERFLOW3]]
+; CHECK-NEXT:    [[TMP9:%.*]] = or i1 [[TMP4]], [[TMP8]]
+; CHECK-NEXT:    br i1 [[TMP9]], label %[[SCALAR_PH]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[N]], 8
+; CHECK-NEXT:    [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
+; CHECK-NEXT:    [[TMP10:%.*]] = mul i64 [[N_VEC]], 4
+; CHECK-NEXT:    [[TMP11:%.*]] = getelementptr i8, ptr [[P]], i64 [[TMP10]]
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i16> poison, i16 [[VAL]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i16> [[BROADCAST_SPLATINSERT]], <4 x i16> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT4:%.*]] = insertelement <4 x half> poison, half [[FVAL]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT5:%.*]] = shufflevector <4 x half> [[BROADCAST_SPLATINSERT4]], <4 x half> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[OFFSET_IDX:%.*]] = mul i64 [[INDEX]], 4
+; CHECK-NEXT:    [[TMP12:%.*]] = add i64 [[OFFSET_IDX]], 16
+; CHECK-NEXT:    [[NEXT_GEP:%.*]] = getelementptr i8, ptr [[P]], i64 [[OFFSET_IDX]]
+; CHECK-NEXT:    [[NEXT_GEP6:%.*]] = getelementptr i8, ptr [[P]], i64 [[TMP12]]
+; CHECK-NEXT:    [[TMP13:%.*]] = bitcast <4 x i16> [[BROADCAST_SPLAT]] to <4 x half>
+; CHECK-NEXT:    [[TMP14:%.*]] = shufflevector <4 x half> [[TMP13]], <4 x half> [[BROADCAST_SPLAT5]], <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+; CHECK-NEXT:    [[INTERLEAVED_VEC:%.*]] = shufflevector <8 x half> [[TMP14]], <8 x half> poison, <8 x i32> <i32 0, i32 4, i32 1, i32 5, i32 2, i32 6, i32 3, i32 7>
+; CHECK-NEXT:    store <8 x half> [[INTERLEAVED_VEC]], ptr [[NEXT_GEP]], align 2
+; CHECK-NEXT:    store <8 x half> [[INTERLEAVED_VEC]], ptr [[NEXT_GEP6]], align 2
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 8
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[TMP17]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
+; CHECK-NEXT:    br i1 [[CMP_N]], [[END:label %.*]], label %[[SCALAR_PH]]
+; CHECK:       [[SCALAR_PH]]:
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %res = phi ptr [ %p, %entry ], [ %res.next, %loop ]
+  store i16 %val, ptr %res
+  %res.offset = getelementptr i16, ptr %res, i64 1
+  store half %fval, ptr %res.offset
+  %res.next = getelementptr i16, ptr %res, i64 2
+  %iv.next = add i64 %iv, 1
+  %exit.cond = icmp eq i64 %iv.next, %n
+  br i1 %exit.cond, label %end, label %loop
+
+end:
+  ret void
+}