[llvm] [VPlan] Don't fold UDiv in replicate regions. (PR #175460)

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Sun Jan 11 13:18:24 PST 2026


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-vectorizers

Author: Florian Hahn (fhahn)

<details>
<summary>Changes</summary>

The UDiv fold added in d12e993 (#<!-- -->174581) is currently also applied to replicate regions, which means we may end up with VPInstructions in replicate regions, which is currently nots supported.

Fixes https://github.com/llvm/llvm-project/issues/175295.

---
Full diff: https://github.com/llvm/llvm-project/pull/175460.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp (+6-1) 
- (added) llvm/test/Transforms/LoopVectorize/X86/predicated-udiv.ll (+310) 


``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index a430f13f0c9c0..19c66e1efb956 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -1352,7 +1352,12 @@ static void simplifyRecipe(VPSingleDefRecipe *Def, VPTypeAnalysis &TypeInfo) {
         {A, Plan->getConstantInt(APC->getBitWidth(), APC->exactLogBase2())},
         *cast<VPRecipeWithIRFlags>(Def), Def->getDebugLoc()));
 
-  if (match(Def, m_UDiv(m_VPValue(A), m_APInt(APC))) && APC->isPowerOf2())
+  // Don't convert udiv to lshr inside a replicate region, as VPInstructions are
+  // not allowed in them.
+  const VPRegionBlock *ParentRegion = Def->getParent()->getParent();
+  bool IsInReplicateRegion = ParentRegion && ParentRegion->isReplicator();
+  if (!IsInReplicateRegion && match(Def, m_UDiv(m_VPValue(A), m_APInt(APC))) &&
+      APC->isPowerOf2())
     return Def->replaceAllUsesWith(Builder.createNaryOp(
         Instruction::LShr,
         {A, Plan->getConstantInt(APC->getBitWidth(), APC->exactLogBase2())}, {},
diff --git a/llvm/test/Transforms/LoopVectorize/X86/predicated-udiv.ll b/llvm/test/Transforms/LoopVectorize/X86/predicated-udiv.ll
new file mode 100644
index 0000000000000..45f211b9b5284
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/X86/predicated-udiv.ll
@@ -0,0 +1,310 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals none --version 5
+; RUN: opt -p loop-vectorize -force-vector-width=4 -force-vector-interleave=2 -S %s | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Test case for https://github.com/llvm/llvm-project/issues/175295.
+define i32 @simplify_udiv_1_in_replicate_region(i8 %arg, ptr %src) {
+; CHECK-LABEL: define i32 @simplify_udiv_1_in_replicate_region(
+; CHECK-SAME: i8 [[ARG:%.*]], ptr [[SRC:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = or i8 [[ARG]], 1
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i8> poison, i8 [[TMP0]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i8> [[BROADCAST_SPLATINSERT]], <4 x i8> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP1:%.*]] = lshr <4 x i8> [[BROADCAST_SPLAT]], zeroinitializer
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i8, ptr [[SRC]], i32 [[INDEX]]
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[TMP2]], i64 4
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <4 x i8>, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq <4 x i8> [[WIDE_LOAD]], zeroinitializer
+; CHECK-NEXT:    [[PREDPHI:%.*]] = select <4 x i1> [[TMP4]], <4 x i8> zeroinitializer, <4 x i8> [[TMP1]]
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp ne <4 x i8> [[PREDPHI]], zeroinitializer
+; CHECK-NEXT:    [[TMP6:%.*]] = zext <4 x i1> [[TMP5]] to <4 x i32>
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 8
+; CHECK-NEXT:    [[TMP7:%.*]] = icmp eq i32 [[INDEX_NEXT]], 16
+; CHECK-NEXT:    br i1 [[TMP7]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[VECTOR_RECUR_EXTRACT:%.*]] = extractelement <4 x i32> [[TMP6]], i32 3
+; CHECK-NEXT:    br label %[[SCALAR_PH:.*]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 16, %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LATCH:.*]] ]
+; CHECK-NEXT:    [[RECUR:%.*]] = phi i32 [ [[VECTOR_RECUR_EXTRACT]], %[[SCALAR_PH]] ], [ [[ZEXT:%.*]], %[[LATCH]] ]
+; CHECK-NEXT:    [[GEP_SRC:%.*]] = getelementptr inbounds i8, ptr [[SRC]], i32 [[IV]]
+; CHECK-NEXT:    [[L:%.*]] = load i8, ptr [[GEP_SRC]], align 1
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i8 [[L]], 0
+; CHECK-NEXT:    br i1 [[C]], label %[[LATCH]], label %[[THEN:.*]]
+; CHECK:       [[THEN]]:
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[ARG]], 1
+; CHECK-NEXT:    [[UDIV:%.*]] = udiv i8 [[OR]], 1
+; CHECK-NEXT:    br label %[[LATCH]]
+; CHECK:       [[LATCH]]:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ [[UDIV]], %[[THEN]] ], [ 0, %[[LOOP]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[PHI]], 0
+; CHECK-NEXT:    [[ZEXT]] = zext i1 [[CMP]] to i32
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT:    [[EC:%.*]] = icmp eq i32 [[IV]], 18
+; CHECK-NEXT:    br i1 [[EC]], label %[[EXIT:.*]], label %[[LOOP]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret i32 0
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %latch ]
+  %recur = phi i32 [ 0, %entry ], [ %zext, %latch ]
+  %gep.src = getelementptr inbounds i8, ptr %src, i32 %iv
+  %l = load i8, ptr %gep.src
+  %c = icmp eq i8 %l, 0
+  br i1 %c, label %latch, label %then
+
+then:
+  %or = or i8 %arg, 1
+  %udiv = udiv i8 %or, 1
+  br label %latch
+
+latch:
+  %phi = phi i8 [ %udiv, %then ], [ 0, %loop ]
+  %cmp = icmp ne i8 %phi, 0
+  %zext = zext i1 %cmp to i32
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv, 18
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret i32 0
+}
+
+define i32 @simplify_udiv_4_in_replicate_region2(i8 %arg, ptr noalias %src, ptr %dst) {
+; CHECK-LABEL: define i32 @simplify_udiv_4_in_replicate_region2(
+; CHECK-SAME: i8 [[ARG:%.*]], ptr noalias [[SRC:%.*]], ptr [[DST:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_STORE_CONTINUE29:.*]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[INDEX]], 0
+; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[INDEX]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = add i32 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP3:%.*]] = add i32 [[INDEX]], 3
+; CHECK-NEXT:    [[TMP4:%.*]] = add i32 [[INDEX]], 4
+; CHECK-NEXT:    [[TMP5:%.*]] = add i32 [[INDEX]], 5
+; CHECK-NEXT:    [[TMP6:%.*]] = add i32 [[INDEX]], 6
+; CHECK-NEXT:    [[TMP7:%.*]] = add i32 [[INDEX]], 7
+; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds i8, ptr [[SRC]], i32 [[TMP0]]
+; CHECK-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[TMP8]], i64 4
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <4 x i8>, ptr [[TMP8]], align 1
+; CHECK-NEXT:    [[WIDE_LOAD1:%.*]] = load <4 x i8>, ptr [[TMP9]], align 1
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp ne <4 x i8> [[WIDE_LOAD]], zeroinitializer
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp ne <4 x i8> [[WIDE_LOAD1]], zeroinitializer
+; CHECK-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[TMP0]]
+; CHECK-NEXT:    [[TMP13:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[TMP1]]
+; CHECK-NEXT:    [[TMP14:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[TMP2]]
+; CHECK-NEXT:    [[TMP15:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[TMP3]]
+; CHECK-NEXT:    [[TMP16:%.*]] = insertelement <4 x ptr> poison, ptr [[TMP12]], i32 0
+; CHECK-NEXT:    [[TMP17:%.*]] = insertelement <4 x ptr> [[TMP16]], ptr [[TMP13]], i32 1
+; CHECK-NEXT:    [[TMP18:%.*]] = insertelement <4 x ptr> [[TMP17]], ptr [[TMP14]], i32 2
+; CHECK-NEXT:    [[TMP19:%.*]] = insertelement <4 x ptr> [[TMP18]], ptr [[TMP15]], i32 3
+; CHECK-NEXT:    [[TMP20:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[TMP4]]
+; CHECK-NEXT:    [[TMP21:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[TMP5]]
+; CHECK-NEXT:    [[TMP22:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[TMP6]]
+; CHECK-NEXT:    [[TMP23:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[TMP7]]
+; CHECK-NEXT:    [[TMP24:%.*]] = insertelement <4 x ptr> poison, ptr [[TMP20]], i32 0
+; CHECK-NEXT:    [[TMP25:%.*]] = insertelement <4 x ptr> [[TMP24]], ptr [[TMP21]], i32 1
+; CHECK-NEXT:    [[TMP26:%.*]] = insertelement <4 x ptr> [[TMP25]], ptr [[TMP22]], i32 2
+; CHECK-NEXT:    [[TMP27:%.*]] = insertelement <4 x ptr> [[TMP26]], ptr [[TMP23]], i32 3
+; CHECK-NEXT:    [[TMP28:%.*]] = extractelement <4 x i1> [[TMP10]], i32 0
+; CHECK-NEXT:    br i1 [[TMP28]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
+; CHECK:       [[PRED_LOAD_IF]]:
+; CHECK-NEXT:    [[TMP29:%.*]] = load i8, ptr [[TMP12]], align 1
+; CHECK-NEXT:    [[TMP30:%.*]] = insertelement <4 x i8> poison, i8 [[TMP29]], i32 0
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE]]
+; CHECK:       [[PRED_LOAD_CONTINUE]]:
+; CHECK-NEXT:    [[TMP31:%.*]] = phi <4 x i8> [ poison, %[[VECTOR_BODY]] ], [ [[TMP30]], %[[PRED_LOAD_IF]] ]
+; CHECK-NEXT:    [[TMP32:%.*]] = extractelement <4 x i1> [[TMP10]], i32 1
+; CHECK-NEXT:    br i1 [[TMP32]], label %[[PRED_LOAD_IF2:.*]], label %[[PRED_LOAD_CONTINUE3:.*]]
+; CHECK:       [[PRED_LOAD_IF2]]:
+; CHECK-NEXT:    [[TMP33:%.*]] = load i8, ptr [[TMP13]], align 1
+; CHECK-NEXT:    [[TMP34:%.*]] = insertelement <4 x i8> [[TMP31]], i8 [[TMP33]], i32 1
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE3]]
+; CHECK:       [[PRED_LOAD_CONTINUE3]]:
+; CHECK-NEXT:    [[TMP35:%.*]] = phi <4 x i8> [ [[TMP31]], %[[PRED_LOAD_CONTINUE]] ], [ [[TMP34]], %[[PRED_LOAD_IF2]] ]
+; CHECK-NEXT:    [[TMP36:%.*]] = extractelement <4 x i1> [[TMP10]], i32 2
+; CHECK-NEXT:    br i1 [[TMP36]], label %[[PRED_LOAD_IF4:.*]], label %[[PRED_LOAD_CONTINUE5:.*]]
+; CHECK:       [[PRED_LOAD_IF4]]:
+; CHECK-NEXT:    [[TMP37:%.*]] = load i8, ptr [[TMP14]], align 1
+; CHECK-NEXT:    [[TMP38:%.*]] = insertelement <4 x i8> [[TMP35]], i8 [[TMP37]], i32 2
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE5]]
+; CHECK:       [[PRED_LOAD_CONTINUE5]]:
+; CHECK-NEXT:    [[TMP39:%.*]] = phi <4 x i8> [ [[TMP35]], %[[PRED_LOAD_CONTINUE3]] ], [ [[TMP38]], %[[PRED_LOAD_IF4]] ]
+; CHECK-NEXT:    [[TMP40:%.*]] = extractelement <4 x i1> [[TMP10]], i32 3
+; CHECK-NEXT:    br i1 [[TMP40]], label %[[PRED_LOAD_IF6:.*]], label %[[PRED_LOAD_CONTINUE7:.*]]
+; CHECK:       [[PRED_LOAD_IF6]]:
+; CHECK-NEXT:    [[TMP41:%.*]] = load i8, ptr [[TMP15]], align 1
+; CHECK-NEXT:    [[TMP42:%.*]] = insertelement <4 x i8> [[TMP39]], i8 [[TMP41]], i32 3
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE7]]
+; CHECK:       [[PRED_LOAD_CONTINUE7]]:
+; CHECK-NEXT:    [[TMP43:%.*]] = phi <4 x i8> [ [[TMP39]], %[[PRED_LOAD_CONTINUE5]] ], [ [[TMP42]], %[[PRED_LOAD_IF6]] ]
+; CHECK-NEXT:    [[TMP44:%.*]] = extractelement <4 x i1> [[TMP11]], i32 0
+; CHECK-NEXT:    br i1 [[TMP44]], label %[[PRED_LOAD_IF8:.*]], label %[[PRED_LOAD_CONTINUE9:.*]]
+; CHECK:       [[PRED_LOAD_IF8]]:
+; CHECK-NEXT:    [[TMP45:%.*]] = load i8, ptr [[TMP20]], align 1
+; CHECK-NEXT:    [[TMP46:%.*]] = insertelement <4 x i8> poison, i8 [[TMP45]], i32 0
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE9]]
+; CHECK:       [[PRED_LOAD_CONTINUE9]]:
+; CHECK-NEXT:    [[TMP47:%.*]] = phi <4 x i8> [ poison, %[[PRED_LOAD_CONTINUE7]] ], [ [[TMP46]], %[[PRED_LOAD_IF8]] ]
+; CHECK-NEXT:    [[TMP48:%.*]] = extractelement <4 x i1> [[TMP11]], i32 1
+; CHECK-NEXT:    br i1 [[TMP48]], label %[[PRED_LOAD_IF10:.*]], label %[[PRED_LOAD_CONTINUE11:.*]]
+; CHECK:       [[PRED_LOAD_IF10]]:
+; CHECK-NEXT:    [[TMP49:%.*]] = load i8, ptr [[TMP21]], align 1
+; CHECK-NEXT:    [[TMP50:%.*]] = insertelement <4 x i8> [[TMP47]], i8 [[TMP49]], i32 1
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE11]]
+; CHECK:       [[PRED_LOAD_CONTINUE11]]:
+; CHECK-NEXT:    [[TMP51:%.*]] = phi <4 x i8> [ [[TMP47]], %[[PRED_LOAD_CONTINUE9]] ], [ [[TMP50]], %[[PRED_LOAD_IF10]] ]
+; CHECK-NEXT:    [[TMP52:%.*]] = extractelement <4 x i1> [[TMP11]], i32 2
+; CHECK-NEXT:    br i1 [[TMP52]], label %[[PRED_LOAD_IF12:.*]], label %[[PRED_LOAD_CONTINUE13:.*]]
+; CHECK:       [[PRED_LOAD_IF12]]:
+; CHECK-NEXT:    [[TMP53:%.*]] = load i8, ptr [[TMP22]], align 1
+; CHECK-NEXT:    [[TMP54:%.*]] = insertelement <4 x i8> [[TMP51]], i8 [[TMP53]], i32 2
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE13]]
+; CHECK:       [[PRED_LOAD_CONTINUE13]]:
+; CHECK-NEXT:    [[TMP55:%.*]] = phi <4 x i8> [ [[TMP51]], %[[PRED_LOAD_CONTINUE11]] ], [ [[TMP54]], %[[PRED_LOAD_IF12]] ]
+; CHECK-NEXT:    [[TMP56:%.*]] = extractelement <4 x i1> [[TMP11]], i32 3
+; CHECK-NEXT:    br i1 [[TMP56]], label %[[PRED_LOAD_IF14:.*]], label %[[PRED_LOAD_CONTINUE15:.*]]
+; CHECK:       [[PRED_LOAD_IF14]]:
+; CHECK-NEXT:    [[TMP57:%.*]] = load i8, ptr [[TMP23]], align 1
+; CHECK-NEXT:    [[TMP58:%.*]] = insertelement <4 x i8> [[TMP55]], i8 [[TMP57]], i32 3
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE15]]
+; CHECK:       [[PRED_LOAD_CONTINUE15]]:
+; CHECK-NEXT:    [[TMP59:%.*]] = phi <4 x i8> [ [[TMP55]], %[[PRED_LOAD_CONTINUE13]] ], [ [[TMP58]], %[[PRED_LOAD_IF14]] ]
+; CHECK-NEXT:    [[TMP60:%.*]] = lshr <4 x i8> [[TMP43]], splat (i8 1)
+; CHECK-NEXT:    [[TMP61:%.*]] = lshr <4 x i8> [[TMP59]], splat (i8 1)
+; CHECK-NEXT:    [[TMP62:%.*]] = extractelement <4 x i1> [[TMP10]], i32 0
+; CHECK-NEXT:    br i1 [[TMP62]], label %[[PRED_STORE_IF:.*]], label %[[PRED_STORE_CONTINUE:.*]]
+; CHECK:       [[PRED_STORE_IF]]:
+; CHECK-NEXT:    [[TMP63:%.*]] = extractelement <4 x i8> [[TMP60]], i32 0
+; CHECK-NEXT:    store i8 [[TMP63]], ptr [[TMP12]], align 1
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE]]
+; CHECK:       [[PRED_STORE_CONTINUE]]:
+; CHECK-NEXT:    [[TMP64:%.*]] = extractelement <4 x i1> [[TMP10]], i32 1
+; CHECK-NEXT:    br i1 [[TMP64]], label %[[PRED_STORE_IF16:.*]], label %[[PRED_STORE_CONTINUE17:.*]]
+; CHECK:       [[PRED_STORE_IF16]]:
+; CHECK-NEXT:    [[TMP65:%.*]] = extractelement <4 x i8> [[TMP60]], i32 1
+; CHECK-NEXT:    store i8 [[TMP65]], ptr [[TMP13]], align 1
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE17]]
+; CHECK:       [[PRED_STORE_CONTINUE17]]:
+; CHECK-NEXT:    [[TMP66:%.*]] = extractelement <4 x i1> [[TMP10]], i32 2
+; CHECK-NEXT:    br i1 [[TMP66]], label %[[PRED_STORE_IF18:.*]], label %[[PRED_STORE_CONTINUE19:.*]]
+; CHECK:       [[PRED_STORE_IF18]]:
+; CHECK-NEXT:    [[TMP67:%.*]] = extractelement <4 x i8> [[TMP60]], i32 2
+; CHECK-NEXT:    store i8 [[TMP67]], ptr [[TMP14]], align 1
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE19]]
+; CHECK:       [[PRED_STORE_CONTINUE19]]:
+; CHECK-NEXT:    [[TMP68:%.*]] = extractelement <4 x i1> [[TMP10]], i32 3
+; CHECK-NEXT:    br i1 [[TMP68]], label %[[PRED_STORE_IF20:.*]], label %[[PRED_STORE_CONTINUE21:.*]]
+; CHECK:       [[PRED_STORE_IF20]]:
+; CHECK-NEXT:    [[TMP69:%.*]] = extractelement <4 x i8> [[TMP60]], i32 3
+; CHECK-NEXT:    store i8 [[TMP69]], ptr [[TMP15]], align 1
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE21]]
+; CHECK:       [[PRED_STORE_CONTINUE21]]:
+; CHECK-NEXT:    [[TMP70:%.*]] = extractelement <4 x i1> [[TMP11]], i32 0
+; CHECK-NEXT:    br i1 [[TMP70]], label %[[PRED_STORE_IF22:.*]], label %[[PRED_STORE_CONTINUE23:.*]]
+; CHECK:       [[PRED_STORE_IF22]]:
+; CHECK-NEXT:    [[TMP71:%.*]] = extractelement <4 x i8> [[TMP61]], i32 0
+; CHECK-NEXT:    store i8 [[TMP71]], ptr [[TMP20]], align 1
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE23]]
+; CHECK:       [[PRED_STORE_CONTINUE23]]:
+; CHECK-NEXT:    [[TMP72:%.*]] = extractelement <4 x i1> [[TMP11]], i32 1
+; CHECK-NEXT:    br i1 [[TMP72]], label %[[PRED_STORE_IF24:.*]], label %[[PRED_STORE_CONTINUE25:.*]]
+; CHECK:       [[PRED_STORE_IF24]]:
+; CHECK-NEXT:    [[TMP73:%.*]] = extractelement <4 x i8> [[TMP61]], i32 1
+; CHECK-NEXT:    store i8 [[TMP73]], ptr [[TMP21]], align 1
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE25]]
+; CHECK:       [[PRED_STORE_CONTINUE25]]:
+; CHECK-NEXT:    [[TMP74:%.*]] = extractelement <4 x i1> [[TMP11]], i32 2
+; CHECK-NEXT:    br i1 [[TMP74]], label %[[PRED_STORE_IF26:.*]], label %[[PRED_STORE_CONTINUE27:.*]]
+; CHECK:       [[PRED_STORE_IF26]]:
+; CHECK-NEXT:    [[TMP75:%.*]] = extractelement <4 x i8> [[TMP61]], i32 2
+; CHECK-NEXT:    store i8 [[TMP75]], ptr [[TMP22]], align 1
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE27]]
+; CHECK:       [[PRED_STORE_CONTINUE27]]:
+; CHECK-NEXT:    [[TMP76:%.*]] = extractelement <4 x i1> [[TMP11]], i32 3
+; CHECK-NEXT:    br i1 [[TMP76]], label %[[PRED_STORE_IF28:.*]], label %[[PRED_STORE_CONTINUE29]]
+; CHECK:       [[PRED_STORE_IF28]]:
+; CHECK-NEXT:    [[TMP77:%.*]] = extractelement <4 x i8> [[TMP61]], i32 3
+; CHECK-NEXT:    store i8 [[TMP77]], ptr [[TMP23]], align 1
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE29]]
+; CHECK:       [[PRED_STORE_CONTINUE29]]:
+; CHECK-NEXT:    [[PREDPHI:%.*]] = select <4 x i1> [[TMP11]], <4 x i8> [[TMP61]], <4 x i8> zeroinitializer
+; CHECK-NEXT:    [[TMP78:%.*]] = icmp ne <4 x i8> [[PREDPHI]], zeroinitializer
+; CHECK-NEXT:    [[TMP79:%.*]] = zext <4 x i1> [[TMP78]] to <4 x i32>
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 8
+; CHECK-NEXT:    [[TMP80:%.*]] = icmp eq i32 [[INDEX_NEXT]], 16
+; CHECK-NEXT:    br i1 [[TMP80]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[VECTOR_RECUR_EXTRACT:%.*]] = extractelement <4 x i32> [[TMP79]], i32 3
+; CHECK-NEXT:    br label %[[SCALAR_PH:.*]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 16, %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LATCH:.*]] ]
+; CHECK-NEXT:    [[RECUR:%.*]] = phi i32 [ [[VECTOR_RECUR_EXTRACT]], %[[SCALAR_PH]] ], [ [[ZEXT:%.*]], %[[LATCH]] ]
+; CHECK-NEXT:    [[GEP_SRC:%.*]] = getelementptr inbounds i8, ptr [[SRC]], i32 [[IV]]
+; CHECK-NEXT:    [[L:%.*]] = load i8, ptr [[GEP_SRC]], align 1
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i8 [[L]], 0
+; CHECK-NEXT:    br i1 [[C]], label %[[LATCH]], label %[[THEN:.*]]
+; CHECK:       [[THEN]]:
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[ARG]], 1
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds i8, ptr [[DST]], i32 [[IV]]
+; CHECK-NEXT:    [[L_2:%.*]] = load i8, ptr [[GEP]], align 1
+; CHECK-NEXT:    [[UDIV:%.*]] = udiv i8 [[L_2]], 2
+; CHECK-NEXT:    store i8 [[UDIV]], ptr [[GEP]], align 1
+; CHECK-NEXT:    br label %[[LATCH]]
+; CHECK:       [[LATCH]]:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i8 [ [[UDIV]], %[[THEN]] ], [ 0, %[[LOOP]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[PHI]], 0
+; CHECK-NEXT:    [[ZEXT]] = zext i1 [[CMP]] to i32
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT:    [[EC:%.*]] = icmp eq i32 [[IV]], 18
+; CHECK-NEXT:    br i1 [[EC]], label %[[EXIT:.*]], label %[[LOOP]], !llvm.loop [[LOOP5:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret i32 0
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %latch ]
+  %recur = phi i32 [ 0, %entry ], [ %zext, %latch ]
+  %gep.src = getelementptr inbounds i8, ptr %src, i32 %iv
+  %l = load i8, ptr %gep.src
+  %c = icmp eq i8 %l, 0
+  br i1 %c, label %latch, label %then
+
+then:
+  %or = or i8 %arg, 1
+  %gep = getelementptr inbounds i8, ptr %dst, i32 %iv
+  %l.2 = load i8, ptr %gep
+  %udiv = udiv i8 %l.2, 2
+  store i8 %udiv, ptr %gep
+  br label %latch
+
+latch:
+  %phi = phi i8 [ %udiv, %then ], [ 0, %loop ]
+  %cmp = icmp ne i8 %phi, 0
+  %zext = zext i1 %cmp to i32
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv, 18
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret i32 0
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/175460


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