[VPlan] Truncate VFxUF if needed in VPWidenPointerInduction::execute.

Create truncate if needed after 56b05a0. Note that this preserves the
original behavior pre 56b05a0. If truncate would strip any set bits,
then the explicit computation in the narrower type would wrap.

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -3366,8 +3366,10 @@ void VPWidenPointerInductionRecipe::execute(VPTransformState &State) {
 
     Value *InductionGEP = GetElementPtrInst::Create(
         State.Builder.getInt8Ty(), NewPointerPhi,
-        State.Builder.CreateMul(ScalarStepValue, NumUnrolledElems), "ptr.ind",
-        InductionLoc);
+        State.Builder.CreateMul(
+            ScalarStepValue,
+            State.Builder.CreateTrunc(NumUnrolledElems, PhiType)),
+        "ptr.ind", InductionLoc);
 
     NewPointerPhi->addIncoming(InductionGEP, VectorPH);
   }

llvm/test/Transforms/LoopVectorize/pointer-induction-index-width-smaller-than-iv-width.ll

@@ -0,0 +1,89 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -p loop-vectorize -force-vector-width=4 -S %s | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+
+; Test case where the pointer index with is 32 bits, but the main IV is 64 bit.
+; Make sure VFxUF is adjusted accordingly.
+define void @wide_ptr_induction_index_width_smaller_than_iv_width(ptr noalias %src, ptr noalias %dst.0, ptr noalias %dst.1) {
+; CHECK-LABEL: define void @wide_ptr_induction_index_width_smaller_than_iv_width(
+; CHECK-SAME: ptr noalias [[SRC:%.*]], ptr noalias [[DST_0:%.*]], ptr noalias [[DST_1:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr i8, ptr [[SRC]], i32 800
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[POINTER_PHI:%.*]] = phi ptr [ [[SRC]], %[[VECTOR_PH]] ], [ [[PTR_IND:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VECTOR_GEP:%.*]] = getelementptr i8, ptr [[POINTER_PHI]], <4 x i32> <i32 0, i32 8, i32 16, i32 24>
+; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[INDEX]], 0
+; CHECK-NEXT:    [[TMP2:%.*]] = add i64 [[INDEX]], 1
+; CHECK-NEXT:    [[TMP3:%.*]] = add i64 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP4:%.*]] = add i64 [[INDEX]], 3
+; CHECK-NEXT:    [[TMP5:%.*]] = extractelement <4 x ptr> [[VECTOR_GEP]], i32 0
+; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr i64, ptr [[TMP5]], i32 0
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <4 x i64>, ptr [[TMP6]], align 1
+; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds i64, ptr [[DST_0]], i64 [[TMP1]]
+; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds i64, ptr [[DST_0]], i64 [[TMP2]]
+; CHECK-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i64, ptr [[DST_0]], i64 [[TMP3]]
+; CHECK-NEXT:    [[TMP10:%.*]] = getelementptr inbounds i64, ptr [[DST_0]], i64 [[TMP4]]
+; CHECK-NEXT:    [[TMP11:%.*]] = getelementptr inbounds i64, ptr [[TMP7]], i32 0
+; CHECK-NEXT:    store <4 x i64> [[WIDE_LOAD]], ptr [[TMP11]], align 8
+; CHECK-NEXT:    store ptr [[TMP5]], ptr [[TMP7]], align 8
+; CHECK-NEXT:    [[TMP12:%.*]] = extractelement <4 x ptr> [[VECTOR_GEP]], i32 1
+; CHECK-NEXT:    store ptr [[TMP12]], ptr [[TMP8]], align 8
+; CHECK-NEXT:    [[TMP13:%.*]] = extractelement <4 x ptr> [[VECTOR_GEP]], i32 2
+; CHECK-NEXT:    store ptr [[TMP13]], ptr [[TMP9]], align 8
+; CHECK-NEXT:    [[TMP14:%.*]] = extractelement <4 x ptr> [[VECTOR_GEP]], i32 3
+; CHECK-NEXT:    store ptr [[TMP14]], ptr [[TMP10]], align 8
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
+; CHECK-NEXT:    [[PTR_IND]] = getelementptr i8, ptr [[POINTER_PHI]], i32 32
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp eq i64 [[INDEX_NEXT]], 100
+; CHECK-NEXT:    br i1 [[TMP15]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    br i1 false, label %[[EXIT:.*]], label %[[SCALAR_PH]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ 100, %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    [[BC_RESUME_VAL1:%.*]] = phi ptr [ [[TMP0]], %[[MIDDLE_BLOCK]] ], [ [[SRC]], %[[ENTRY]] ]
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[PTR_IV:%.*]] = phi ptr [ [[BC_RESUME_VAL1]], %[[SCALAR_PH]] ], [ [[PTR_IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[L:%.*]] = load i64, ptr [[PTR_IV]], align 1
+; CHECK-NEXT:    [[GEP_DST_1:%.*]] = getelementptr inbounds i64, ptr [[DST_0]], i64 [[IV]]
+; CHECK-NEXT:    store i64 [[L]], ptr [[GEP_DST_1]], align 8
+; CHECK-NEXT:    [[GEP_DST_0:%.*]] = getelementptr inbounds ptr, ptr [[DST_1]], i64 [[IV]]
+; CHECK-NEXT:    store ptr [[PTR_IV]], ptr [[GEP_DST_1]], align 8
+; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
+; CHECK-NEXT:    [[PTR_IV_NEXT]] = getelementptr i8, ptr [[PTR_IV]], i32 8
+; CHECK-NEXT:    [[EC:%.*]] = icmp ult i64 [[IV]], 100
+; CHECK-NEXT:    br i1 [[EC]], label %[[LOOP]], label %[[EXIT]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %ptr.iv = phi ptr [ %src, %entry ], [ %ptr.iv.next, %loop ]
+  %l = load i64, ptr %ptr.iv, align 1
+  %gep.dst.1 = getelementptr inbounds i64, ptr %dst.0, i64 %iv
+  store i64 %l, ptr %gep.dst.1, align 8
+  %gep.dst.0 = getelementptr inbounds ptr, ptr %dst.1, i64 %iv
+  store ptr %ptr.iv, ptr %gep.dst.1, align 8
+  %iv.next = add i64 %iv, 1
+  %ptr.iv.next = getelementptr i8, ptr %ptr.iv, i32 8
+  %ec = icmp ult i64 %iv, 100
+  br i1 %ec, label %loop, label %exit
+
+exit:
+  ret void
+}
+;.
+; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]]}
+; CHECK: [[META1]] = !{!"llvm.loop.isvectorized", i32 1}
+; CHECK: [[META2]] = !{!"llvm.loop.unroll.runtime.disable"}
+; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META2]], [[META1]]}
+;.