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[LoadStoreVectorizer] Enable vectorization of stores in the presence of an aliasing load

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Summary:
The "getVectorizablePrefix" method would give up if it found an aliasing load for a store chain.
In practice, the aliasing load can be treated as a memory barrier and all stores that precede it
are a valid vectorizable prefix.
Issue found by volkan in D26962. Testcase is a pruned version of the one in the original patch.

Reviewers: jlebar, arsenm, tstellarAMD

Subscribers: mzolotukhin, wdng, nhaehnle, anna, volkan, llvm-commits

Differential Revision: https://reviews.llvm.org/D27008

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287781 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alina Sbirlea
2016-11-23 17:43:15 +00:00
parent 3e65807a6f
commit 106bcf1838
3 changed files with 86 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
test/Transforms/LoadStoreVectorizer/AMDGPU/insertion-point.ll
+3 -5
View File
@@ -61,13 +61,11 @@ entry:
}
; Here we have four stores, with an aliasing load before the last one. We can
; vectorize the first two stores as <2 x float>, but this vectorized store must
; be inserted at the location of the second scalar store, not the fourth one.
; vectorize the first three stores as <3 x float>, but this vectorized store must
; be inserted at the location of the third scalar store, not the fourth one.
;
; CHECK-LABEL: @insert_store_point_alias
; CHECK: store <2 x float>
; CHECK: store float
; CHECK-SAME: %a.idx.2
; CHECK: store <3 x float>
; CHECK: load float, float addrspace(1)* %a.idx.2
; CHECK: store float
; CHECK-SAME: %a.idx.3
test/Transforms/LoadStoreVectorizer/AMDGPU/store_with_aliasing_load.ll
+58
View File
@@ -0,0 +1,58 @@
; RUN: opt -mtriple=amdgcn-amd-amdhsa -load-store-vectorizer -S -o - %s | FileCheck %s
; Check that, in the presence of an aliasing load, the stores preceding the
; aliasing load are safe to vectorize.
; CHECK-LABEL: store_vectorize_with_alias
; CHECK: store <4 x float>
; CHECK: load <4 x float>
; CHECK: store <4 x float>
; Function Attrs: nounwind
define void @store_vectorize_with_alias(i8 addrspace(1)* %a, i8 addrspace(1)* %b) #0 {
bb:
%tmp = bitcast i8 addrspace(1)* %b to float addrspace(1)*
%tmp1 = load float, float addrspace(1)* %tmp, align 4
%tmp2 = bitcast i8 addrspace(1)* %a to float addrspace(1)*
store float %tmp1, float addrspace(1)* %tmp2, align 4
%tmp3 = getelementptr i8, i8 addrspace(1)* %a, i64 4
%tmp4 = bitcast i8 addrspace(1)* %tmp3 to float addrspace(1)*
store float %tmp1, float addrspace(1)* %tmp4, align 4
%tmp5 = getelementptr i8, i8 addrspace(1)* %a, i64 8
%tmp6 = bitcast i8 addrspace(1)* %tmp5 to float addrspace(1)*
store float %tmp1, float addrspace(1)* %tmp6, align 4
%tmp7 = getelementptr i8, i8 addrspace(1)* %a, i64 12
%tmp8 = bitcast i8 addrspace(1)* %tmp7 to float addrspace(1)*
store float %tmp1, float addrspace(1)* %tmp8, align 4
%tmp9 = getelementptr i8, i8 addrspace(1)* %b, i64 16
%tmp10 = bitcast i8 addrspace(1)* %tmp9 to float addrspace(1)*
%tmp11 = load float, float addrspace(1)* %tmp10, align 4
%tmp12 = getelementptr i8, i8 addrspace(1)* %b, i64 20
%tmp13 = bitcast i8 addrspace(1)* %tmp12 to float addrspace(1)*
%tmp14 = load float, float addrspace(1)* %tmp13, align 4
%tmp15 = getelementptr i8, i8 addrspace(1)* %b, i64 24
%tmp16 = bitcast i8 addrspace(1)* %tmp15 to float addrspace(1)*
%tmp17 = load float, float addrspace(1)* %tmp16, align 4
%tmp18 = getelementptr i8, i8 addrspace(1)* %b, i64 28
%tmp19 = bitcast i8 addrspace(1)* %tmp18 to float addrspace(1)*
%tmp20 = load float, float addrspace(1)* %tmp19, align 4
%tmp21 = getelementptr i8, i8 addrspace(1)* %a, i64 16
%tmp22 = bitcast i8 addrspace(1)* %tmp21 to float addrspace(1)*
store float %tmp11, float addrspace(1)* %tmp22, align 4
%tmp23 = getelementptr i8, i8 addrspace(1)* %a, i64 20
%tmp24 = bitcast i8 addrspace(1)* %tmp23 to float addrspace(1)*
store float %tmp14, float addrspace(1)* %tmp24, align 4
%tmp25 = getelementptr i8, i8 addrspace(1)* %a, i64 24
%tmp26 = bitcast i8 addrspace(1)* %tmp25 to float addrspace(1)*
store float %tmp17, float addrspace(1)* %tmp26, align 4
%tmp27 = getelementptr i8, i8 addrspace(1)* %a, i64 28
%tmp28 = bitcast i8 addrspace(1)* %tmp27 to float addrspace(1)*
store float %tmp20, float addrspace(1)* %tmp28, align 4
ret void
}
attributes #0 = { argmemonly nounwind }