[PATCH] D39296: [LSV] Avoid adding vectors of pointers as candidates

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope created this revision.
Herald added a subscriber: nhaehnle.

We no longer add vectors of pointers as candidates for
load/store vectorization. It does not seem to work anyway,
but without this patch we can end up in asserts when trying
to create casts between an integer type and the pointer of
vectors type.

The test case I've added used to assert like this when trying to
cast between i64 and <2 x i16*>:
opt: ../lib/IR/Instructions.cpp:2565: Assertion `castIsValid(op, S, Ty) && "Invalid cast!"' failed.
#0 PrintStackTraceSignalHandler(void*)
#1 SignalHandler(int)
#2 __restore_rt
#3 __GI_raise
#4 __GI_abort
#5 __GI___assert_fail
#6 llvm::CastInst::Create(llvm::Instruction::CastOps, llvm::Value*, llvm::Type*, llvm::Twine const&, llvm::Instruction*)
#7 llvm::IRBuilder<llvm::ConstantFolder, llvm::IRBuilderDefaultInserter>::CreateBitOrPointerCast(llvm::Value*, llvm::Type*, llvm::Twine const&)
#8 Vectorizer::vectorizeStoreChain(llvm::ArrayRef<llvm::Instruction*>, llvm::SmallPtrSet<llvm::Instruction*, 16u>*)


https://reviews.llvm.org/D39296

Files:
  lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
  test/Transforms/LoadStoreVectorizer/AMDGPU/merge-stores.ll


Index: test/Transforms/LoadStoreVectorizer/AMDGPU/merge-stores.ll
===================================================================
--- test/Transforms/LoadStoreVectorizer/AMDGPU/merge-stores.ll
+++ test/Transforms/LoadStoreVectorizer/AMDGPU/merge-stores.ll
@@ -632,6 +632,19 @@
   ret void
 }
 
+
+define amdgpu_kernel void @copy_vec_of_ptrs(<2 x i16*> addrspace(1)* %out,
+                                            <2 x i16*> addrspace(1)* %in ) #0 {
+  %in.gep.1 = getelementptr <2 x i16*>, <2 x i16*> addrspace(1)* %in, i32 1
+  %vec1 = load <2 x i16*>, <2 x i16*> addrspace(1)* %in.gep.1
+  %vec2 = load <2 x i16*>, <2 x i16*> addrspace(1)* %in, align 4
+
+  %out.gep.1 = getelementptr <2 x i16*>, <2 x i16*> addrspace(1)* %out, i32 1
+  store <2 x i16*> %vec1, <2 x i16*> addrspace(1)* %out.gep.1
+  store <2 x i16*> %vec2, <2 x i16*> addrspace(1)* %out, align 4
+  ret void
+}
+
 declare void @llvm.amdgcn.s.barrier() #1
 
 attributes #0 = { nounwind }
Index: lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
===================================================================
--- lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
+++ lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
@@ -615,6 +615,13 @@
       if (!DL.isByteSized(Ty))
         continue;
 
+      // Skip vectors of pointers. The vectorizeLoadChain/vectorizeStoreChain
+      // functions are currently using an integer type for the vectorized
+      // load/store, and does not support casting between the integer type and a
+      // vector of pointers (e.g. i64 to <2 x i16*>)
+      if (Ty->isVectorTy() && Ty->isPtrOrPtrVectorTy())
+        continue;
+
       Value *Ptr = LI->getPointerOperand();
       unsigned AS = Ptr->getType()->getPointerAddressSpace();
       unsigned VecRegSize = TTI.getLoadStoreVecRegBitWidth(AS);
@@ -646,6 +653,13 @@
       if (!VectorType::isValidElementType(Ty->getScalarType()))
         continue;
 
+      // Skip vectors of pointers. The vectorizeLoadChain/vectorizeStoreChain
+      // functions are currently using an integer type for the vectorized
+      // load/store, and does not support casting between the integer type and a
+      // vector of pointers (e.g. i64 to <2 x i16*>)
+      if (Ty->isVectorTy() && Ty->isPtrOrPtrVectorTy())
+        continue;
+
       // Skip weird non-byte sizes. They probably aren't worth the effort of
       // handling correctly.
       if (!DL.isByteSized(Ty))
@@ -701,8 +715,8 @@
   SmallVector<int, 16> Heads, Tails;
   int ConsecutiveChain[64];
 
-  // Do a quadratic search on all of the given stores and find all of the pairs
-  // of stores that follow each other.
+  // Do a quadratic search on all of the given loads/stores and find all of the
+  // pairs of loads/stores that follow each other.
   for (int i = 0, e = Instrs.size(); i < e; ++i) {
     ConsecutiveChain[i] = -1;
     for (int j = e - 1; j >= 0; --j) {
@@ -769,7 +783,7 @@
     SmallPtrSet<Instruction *, 16> *InstructionsProcessed) {
   StoreInst *S0 = cast<StoreInst>(Chain[0]);
 
-  // If the vector has an int element, default to int for the whole load.
+  // If the vector has an int element, default to int for the whole store.
   Type *StoreTy;
   for (Instruction *I : Chain) {
     StoreTy = cast<StoreInst>(I)->getValueOperand()->getType();


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D39296.120271.patch
Type: text/x-patch
Size: 3288 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20171025/bfd66930/attachment.bin>