[PATCH] D20315: [LV] For some induction variables, use vector phis instead of widening the scalar in the loop body

[Elena Demikhovsky via llvm-commits]

delena added inline comments.

================
Comment at: lib/Transforms/Vectorize/LoopVectorize.cpp:2118
@@ +2117,3 @@
+  ConstantInt *Step = II.getConstIntStepValue();
+
+  // Construct the initial value of the vector IV in the vector loop preheader
----------------
mkuper wrote:
> delena wrote:
> > Check (Step != 0) here.
> There's already an assert that this is non-null before each callsite. Do you want another assert here?
Probably yes..

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Comment at: lib/Transforms/Vectorize/LoopVectorize.cpp:2121
@@ +2120,3 @@
+  auto CurrIP = Builder.saveIP();
+  Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator());
+  if (TruncType) {
----------------
I assume that loop invariant code will be hoisted anyway.

================
Comment at: lib/Transforms/Vectorize/LoopVectorize.cpp:4295
@@ +4294,3 @@
+          IntegerType *TruncType = cast<IntegerType>(CI->getType());
+          StepValue = ConstantInt::getSigned(TruncType, StepValue->getSExtValue());
+          if (VF == 1) {
----------------
this line should be moved down, under the if (VF==1)

================
Comment at: lib/Transforms/Vectorize/LoopVectorize.cpp:4306
@@ +4305,3 @@
+            // a new, truncated, vector IV based on that.
+            assert(II.getConstIntStepValue() &&
+              "Primary induction variable should have a const step");
----------------
you don't need assert here, you are under the "if"


http://reviews.llvm.org/D20315