[LV] Add support for insertelt/extractelt processing during type truncation

Summary:
While shrinking types according to the required bits, we can
encounter insert/extract element instructions. This will cause us to
reach an llvm_unreachable statement.

This change adds support for truncating insert/extract element
operations, and adds a regression test.

Reviewers: jmolloy

Subscribers: mzolotukhin, llvm-commits

Differential Revision: http://reviews.llvm.org/D17078

llvm-svn: 260893

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index c5a10ba7b60..a32a0ad0ff5 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3187,6 +3187,9 @@ void InnerLoopVectorizer::truncateToMinimalBitwidths() {
       if (TruncatedTy == OriginalTy)
         continue;
 
+      if (!isa<Instruction>(I))
+        continue;
+
       IRBuilder<> B(cast<Instruction>(I));
       auto ShrinkOperand = [&](Value *V) -> Value* {
         if (auto *ZI = dyn_cast<ZExtInst>(V))
@@ -3242,6 +3245,17 @@ void InnerLoopVectorizer::truncateToMinimalBitwidths() {
       } else if (isa<LoadInst>(I)) {
         // Don't do anything with the operands, just extend the result.
         continue;
+      } else if (auto *IE = dyn_cast<InsertElementInst>(I)) {
+        auto Elements = IE->getOperand(0)->getType()->getVectorNumElements();
+        auto *O0 = B.CreateZExtOrTrunc(
+            IE->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements));
+        auto *O1 = B.CreateZExtOrTrunc(IE->getOperand(1), ScalarTruncatedTy);
+        NewI = B.CreateInsertElement(O0, O1, IE->getOperand(2));
+      } else if (auto *EE = dyn_cast<ExtractElementInst>(I)) {
+        auto Elements = EE->getOperand(0)->getType()->getVectorNumElements();
+        auto *O0 = B.CreateZExtOrTrunc(
+            EE->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements));
+        NewI = B.CreateExtractElement(O0, EE->getOperand(2));
       } else {
         llvm_unreachable("Unhandled instruction type!");
       }