[PATCH] D29776: [LV] Remove type restriction for vector phi creation

[Matthew Simpson via Phabricator via llvm-commits]

mssimpso created this revision.
Herald added a subscriber: mzolotukhin.

We previously only created a vector phi node for an induction variable if its type matched the type of the canonical induction variable. I don't recall why this restriction exists, but it doesn't seem to be necessary.

I'm planning to extend vector phi creation with a few more follow-ons. First, we don't need to require constant-steps (the steps only need to be loop invariant). And second, we can merge the floating point induction widening code into the integer widening code. There's already some overlap, and if we do so, we'll be able to create vector phi nodes for some floating point inductions.


https://reviews.llvm.org/D29776

Files:
  lib/Transforms/Vectorize/LoopVectorize.cpp
  test/Transforms/LoopVectorize/induction.ll


Index: test/Transforms/LoopVectorize/induction.ll
===================================================================
--- test/Transforms/LoopVectorize/induction.ll
+++ test/Transforms/LoopVectorize/induction.ll
@@ -7,11 +7,19 @@
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 
 ; Make sure that we can handle multiple integer induction variables.
+;
 ; CHECK-LABEL: @multi_int_induction(
-; CHECK: vector.body:
-; CHECK:  %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
-; CHECK:  %[[VAR:.*]] = trunc i64 %index to i32
-; CHECK:  %offset.idx = add i32 190, %[[VAR]]
+; CHECK:       vector.body:
+; CHECK-NEXT:    %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
+; CHECK-NEXT:    %vec.ind = phi <2 x i32> [ <i32 190, i32 191>, %vector.ph ], [ %vec.ind.next, %vector.body ]
+; CHECK:         [[TMP3:%.*]] = add i64 %index, 0
+; CHECK-NEXT:    [[TMP4:%.*]] = getelementptr inbounds i32, i32* %A, i64 [[TMP3]]
+; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr i32, i32* [[TMP4]], i32 0
+; CHECK-NEXT:    [[TMP6:%.*]] = bitcast i32* [[TMP5]] to <2 x i32>*
+; CHECK-NEXT:    store <2 x i32> %vec.ind, <2 x i32>* [[TMP6]], align 4
+; CHECK:         %index.next = add i64 %index, 2
+; CHECK-NEXT:    %vec.ind.next = add <2 x i32> %vec.ind, <i32 2, i32 2>
+; CHECK:         br i1 {{.*}}, label %middle.block, label %vector.body
 define void @multi_int_induction(i32* %A, i32 %N) {
 for.body.lr.ph:
   br label %for.body
Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -2421,8 +2421,7 @@
   // Try to create a new independent vector induction variable. If we can't
   // create the phi node, we will splat the scalar induction variable in each
   // loop iteration.
-  if (VF > 1 && IV->getType() == Induction->getType() && Step &&
-      !shouldScalarizeInstruction(EntryVal)) {
+  if (VF > 1 && Step && !shouldScalarizeInstruction(EntryVal)) {
     createVectorIntInductionPHI(ID, EntryVal);
     VectorizedIV = true;
   }


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