[LoopIdiom] Strip exotic scenario

Author: artagnon

llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp

@@ -1545,12 +1545,6 @@ bool LoopIdiomRecognize::optimizeCRCLoop(const PolynomialInfo &Info) {
   if (TT.getArch() == Triple::hexagon)
     return false;
 
-  // Check that the DataLayout allows us to index into the new 256-entry CRC
-  // table.
-  Type *IdxTy = SE->getDataLayout().getIndexType(M.getContext(), 0);
-  if (IdxTy->getIntegerBitWidth() < 8)
-    return false;
-
   // First, create a new GlobalVariable corresponding to the
   // Sarwate-lookup-table.
   Type *CRCTy = Info.LHS->getType();
@@ -1657,7 +1651,9 @@ bool LoopIdiomRecognize::optimizeCRCLoop(const PolynomialInfo &Info) {
                                     : LoByte(Builder, Indexer, "indexer.lo");
 
     // Always index into a GEP using the index type.
-    Indexer = Builder.CreateZExt(Indexer, IdxTy, "indexer.ext");
+    Indexer = Builder.CreateZExt(
+        Indexer, SE->getDataLayout().getIndexType(GV->getType()),
+        "indexer.ext");
 
     // CRCTableLd = CRCTable[(iv'th byte of data) ^ (top|bottom) byte of CRC].
     Value *CRCTableGEP =

llvm/test/Transforms/LoopIdiom/cyclic-redundancy-check-dl.ll

@@ -1,53 +1,33 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals all --version 6
-; RUN: opt -passes=loop-idiom -data-layout="p:16:16" -S %s | FileCheck %s --check-prefix=CHECK-i16
-; RUN: opt -passes=loop-idiom -data-layout="p:1:8" -S %s | FileCheck %s --check-prefix=CHECK-i1
+; RUN: opt -passes=loop-idiom -S %s | FileCheck %s
+
+target datalayout = "p:16:16"
 
 ;.
-; CHECK-i16: @.crctable = private constant [256 x i32] zeroinitializer
+; CHECK: @.crctable = private constant [256 x i32] zeroinitializer
 ;.
 define void @test_with_dl() {
-; CHECK-i16-LABEL: define void @test_with_dl() {
-; CHECK-i16-NEXT:  [[ENTRY:.*]]:
-; CHECK-i16-NEXT:    br label %[[PH:.*]]
-; CHECK-i16:       [[PH_LOOPEXIT:.*]]:
-; CHECK-i16-NEXT:    [[CRC_NEXT_LCSSA:%.*]] = phi i32 [ [[CRC_NEXT3:%.*]], %[[LOOP:.*]] ]
-; CHECK-i16-NEXT:    br label %[[PH]]
-; CHECK-i16:       [[PH]]:
-; CHECK-i16-NEXT:    [[CRC_USE:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[CRC_NEXT_LCSSA]], %[[PH_LOOPEXIT]] ]
-; CHECK-i16-NEXT:    br label %[[LOOP]]
-; CHECK-i16:       [[LOOP]]:
-; CHECK-i16-NEXT:    [[IV:%.*]] = phi i16 [ 0, %[[PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
-; CHECK-i16-NEXT:    [[CRC2:%.*]] = phi i32 [ 0, %[[PH]] ], [ [[CRC_NEXT3]], %[[LOOP]] ]
-; CHECK-i16-NEXT:    [[TMP0:%.*]] = trunc i32 [[CRC2]] to i8
-; CHECK-i16-NEXT:    [[INDEXER_EXT:%.*]] = zext i8 [[TMP0]] to i16
-; CHECK-i16-NEXT:    [[TBL_PTRADD:%.*]] = getelementptr inbounds i32, ptr @.crctable, i16 [[INDEXER_EXT]]
-; CHECK-i16-NEXT:    [[TBL_LD:%.*]] = load i32, ptr [[TBL_PTRADD]], align 4
-; CHECK-i16-NEXT:    [[CRC_LE_SHIFT:%.*]] = lshr i32 [[CRC2]], 8
-; CHECK-i16-NEXT:    [[CRC_NEXT3]] = xor i32 [[CRC_LE_SHIFT]], [[TBL_LD]]
-; CHECK-i16-NEXT:    [[IV_NEXT]] = add i16 [[IV]], 1
-; CHECK-i16-NEXT:    [[EXIT_COND1:%.*]] = icmp ne i16 [[IV]], 0
-; CHECK-i16-NEXT:    br i1 [[EXIT_COND1]], label %[[LOOP]], label %[[PH_LOOPEXIT]]
-;
-; CHECK-i1-LABEL: define void @test_with_dl() {
-; CHECK-i1-NEXT:  [[ENTRY:.*]]:
-; CHECK-i1-NEXT:    br label %[[PH:.*]]
-; CHECK-i1:       [[PH_LOOPEXIT:.*]]:
-; CHECK-i1-NEXT:    [[CRC_NEXT_LCSSA:%.*]] = phi i32 [ [[CRC_NEXT:%.*]], %[[LOOP:.*]] ]
-; CHECK-i1-NEXT:    br label %[[PH]]
-; CHECK-i1:       [[PH]]:
-; CHECK-i1-NEXT:    [[CRC_USE:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[CRC_NEXT_LCSSA]], %[[PH_LOOPEXIT]] ]
-; CHECK-i1-NEXT:    br label %[[LOOP]]
-; CHECK-i1:       [[LOOP]]:
-; CHECK-i1-NEXT:    [[IV:%.*]] = phi i16 [ 0, %[[PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
-; CHECK-i1-NEXT:    [[CRC:%.*]] = phi i32 [ 0, %[[PH]] ], [ [[CRC_NEXT]], %[[LOOP]] ]
-; CHECK-i1-NEXT:    [[LSHR_CRC_1:%.*]] = lshr i32 [[CRC]], 1
-; CHECK-i1-NEXT:    [[CRC_AND_1:%.*]] = and i32 [[CRC]], 1
-; CHECK-i1-NEXT:    [[SB_CHECK:%.*]] = icmp eq i32 [[CRC_AND_1]], 0
-; CHECK-i1-NEXT:    [[XOR:%.*]] = xor i32 [[LSHR_CRC_1]], 0
-; CHECK-i1-NEXT:    [[CRC_NEXT]] = select i1 [[SB_CHECK]], i32 [[LSHR_CRC_1]], i32 [[XOR]]
-; CHECK-i1-NEXT:    [[IV_NEXT]] = add i16 [[IV]], 1
-; CHECK-i1-NEXT:    [[EXIT_COND:%.*]] = icmp ult i16 [[IV]], 7
-; CHECK-i1-NEXT:    br i1 [[EXIT_COND]], label %[[LOOP]], label %[[PH_LOOPEXIT]]
+; CHECK-LABEL: define void @test_with_dl() {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br label %[[PH:.*]]
+; CHECK:       [[PH_LOOPEXIT:.*]]:
+; CHECK-NEXT:    [[CRC_NEXT_LCSSA:%.*]] = phi i32 [ [[CRC_NEXT3:%.*]], %[[LOOP:.*]] ]
+; CHECK-NEXT:    br label %[[PH]]
+; CHECK:       [[PH]]:
+; CHECK-NEXT:    [[CRC_USE:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[CRC_NEXT_LCSSA]], %[[PH_LOOPEXIT]] ]
+; CHECK-NEXT:    br label %[[LOOP]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i16 [ 0, %[[PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[CRC2:%.*]] = phi i32 [ 0, %[[PH]] ], [ [[CRC_NEXT3]], %[[LOOP]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = trunc i32 [[CRC2]] to i8
+; CHECK-NEXT:    [[INDEXER_EXT:%.*]] = zext i8 [[TMP0]] to i16
+; CHECK-NEXT:    [[TBL_PTRADD:%.*]] = getelementptr inbounds i32, ptr @.crctable, i16 [[INDEXER_EXT]]
+; CHECK-NEXT:    [[TBL_LD:%.*]] = load i32, ptr [[TBL_PTRADD]], align 4
+; CHECK-NEXT:    [[CRC_LE_SHIFT:%.*]] = lshr i32 [[CRC2]], 8
+; CHECK-NEXT:    [[CRC_NEXT3]] = xor i32 [[CRC_LE_SHIFT]], [[TBL_LD]]
+; CHECK-NEXT:    [[IV_NEXT]] = add i16 [[IV]], 1
+; CHECK-NEXT:    [[EXIT_COND1:%.*]] = icmp ne i16 [[IV]], 0
+; CHECK-NEXT:    br i1 [[EXIT_COND1]], label %[[LOOP]], label %[[PH_LOOPEXIT]]
 ;
 entry:
   br label %ph