[PATCH] D43812: [WIP][LV] Don't call recordVectorLoopValueForInductionCast for more newly-created IVs from a trunc.

[Andrei Elovikov via Phabricator via llvm-commits]

a.elovikov created this revision.
Herald added a subscriber: hiraditya.

This handles the case that was missed in the r322473 and fixes the assert
mentioned in PR36524.

TODO:

- See if there are other cases that need to be fixed.
- Try to slightly refactore the code to make this logic cleaner.


https://reviews.llvm.org/D43812

Files:
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/test/Transforms/LoopVectorize/X86/pr36524.ll


Index: llvm/test/Transforms/LoopVectorize/X86/pr36524.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopVectorize/X86/pr36524.ll
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -scev-version-unknown -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:1"
+
+define void @foo() {
+; CHECK-LABEL: @foo(
+; CHECK:       vector.body:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH:%.*]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY:%.*]] ]
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i64> [ <i64 2, i64 3, i64 4, i64 5>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[OFFSET_IDX:%.*]] = add i64 2, [[INDEX]]
+; CHECK-NEXT:    [[TMP7:%.*]] = add i64 [[OFFSET_IDX]], 0
+; CHECK-NEXT:    [[TMP8:%.*]] = add i64 [[OFFSET_IDX]], 1
+; CHECK-NEXT:    [[TMP9:%.*]] = add i64 [[OFFSET_IDX]], 2
+; CHECK-NEXT:    [[TMP10:%.*]] = add i64 [[OFFSET_IDX]], 3
+; CHECK-NEXT:    [[OFFSET_IDX1:%.*]] = add i64 2, [[INDEX]]
+; CHECK-NEXT:    [[TMP11:%.*]] = trunc i64 [[OFFSET_IDX1]] to i32
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i32> undef, i32 [[TMP11]], i32 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT]], <4 x i32> undef, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[INDUCTION:%.*]] = add <4 x i32> [[BROADCAST_SPLAT]], <i32 0, i32 1, i32 2, i32 3>
+; CHECK-NEXT:    [[TMP12:%.*]] = add i32 [[TMP11]], 0
+; CHECK-NEXT:    [[INDEX_NEXT]] = add i64 [[INDEX]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <4 x i64> [[VEC_IND]], <i64 4, i64 4, i64 4, i64 4>
+; CHECK-NEXT:    [[TMP13:%.*]] = icmp eq i64 [[INDEX_NEXT]], 80
+; CHECK-NEXT:    br i1 [[TMP13]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !0
+;
+entry:
+  br label %loop
+
+loop:
+  %0 = phi i64 [ 2, %entry ], [ %3, %loop ]
+  %1 = and i64 %0, 4294967295
+  %2 = trunc i64 %0 to i32
+  %3 = add nuw nsw i64 %1, 1
+  %4 = icmp sgt i32 %2, 80
+  br i1 %4, label %exit, label %loop
+
+exit:
+  ret void
+}
Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -573,7 +573,7 @@
   /// Note that \p EntryVal doesn't have to be an induction variable (e.g., it
   /// can be a truncate instruction).
   void buildScalarSteps(Value *ScalarIV, Value *Step, Value *EntryVal,
-                        const InductionDescriptor &ID);
+                        const InductionDescriptor &ID, bool IsNewFromTrunc);
 
   /// Create a vector induction phi node based on an existing scalar one. \p
   /// EntryVal is the value from the original loop that maps to the vector phi
@@ -2594,7 +2594,7 @@
   // in the loop in the common case prior to InstCombine. We will be trading
   // one vector extract for each scalar step.
   if (NeedsScalarIV)
-    buildScalarSteps(ScalarIV, Step, EntryVal, ID);
+    buildScalarSteps(ScalarIV, Step, EntryVal, ID, Trunc);
 }
 
 Value *InnerLoopVectorizer::getStepVector(Value *Val, int StartIdx, Value *Step,
@@ -2655,7 +2655,8 @@
 
 void InnerLoopVectorizer::buildScalarSteps(Value *ScalarIV, Value *Step,
                                            Value *EntryVal,
-                                           const InductionDescriptor &ID) {
+                                           const InductionDescriptor &ID,
+                                           bool IsNewFromTrunc) {
   // We shouldn't have to build scalar steps if we aren't vectorizing.
   assert(VF > 1 && "VF should be greater than one");
 
@@ -2689,7 +2690,8 @@
       auto *Mul = addFastMathFlag(Builder.CreateBinOp(MulOp, StartIdx, Step));
       auto *Add = addFastMathFlag(Builder.CreateBinOp(AddOp, ScalarIV, Mul));
       VectorLoopValueMap.setScalarValue(EntryVal, {Part, Lane}, Add);
-      recordVectorLoopValueForInductionCast(ID, Add, Part, Lane);
+      if (!IsNewFromTrunc)
+        recordVectorLoopValueForInductionCast(ID, Add, Part, Lane);
     }
   }
 }


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