[PATCH] Choose the best consecutive candidate for a store instruction in SLP vectorizer
Wei Mi
wmi at google.com
Mon Jun 22 11:36:57 PDT 2015
Ping.
On Tue, Jun 16, 2015 at 10:14 AM, Wei Mi <wmi at google.com> wrote:
> I changed the patch to remove duplicate code.
>
> Then I run the testsuite with BENCHMARKING_ONLY defined and with turbo mode and address random turned off. It is very helpful and make the perf analysis a lot easier. Thanks!
> I didn't see much perf change with the patch.
>
> Thanks,
> Wei.
>
>
> REPOSITORY
> rL LLVM
>
> http://reviews.llvm.org/D10445
>
> Files:
> lib/Transforms/Vectorize/SLPVectorizer.cpp
> test/Transforms/SLPVectorizer/X86/pr23510.ll
>
> Index: lib/Transforms/Vectorize/SLPVectorizer.cpp
> ===================================================================
> --- lib/Transforms/Vectorize/SLPVectorizer.cpp
> +++ lib/Transforms/Vectorize/SLPVectorizer.cpp
> @@ -3243,15 +3243,26 @@
>
> // Do a quadratic search on all of the given stores and find
> // all of the pairs of stores that follow each other.
> + SmallVector<unsigned, 16> IndexQueue;
> for (unsigned i = 0, e = Stores.size(); i < e; ++i) {
> - for (unsigned j = 0; j < e; ++j) {
> - if (i == j)
> - continue;
> - const DataLayout &DL = Stores[i]->getModule()->getDataLayout();
> - if (R.isConsecutiveAccess(Stores[i], Stores[j], DL)) {
> - Tails.insert(Stores[j]);
> + const DataLayout &DL = Stores[i]->getModule()->getDataLayout();
> + IndexQueue.clear();
> + // If a store has multiple consectutive store candidates, search Stores
> + // array according to the sequence: from i+1 to e, then from i-1 to 0.
> + // This is because usually pairing with immediate succeeding or preceding
> + // candidate create the best chance to find slp vectorization opportunity.
> + unsigned j = 0;
> + for (j = i + 1; j < e; ++j)
> + IndexQueue.push_back(j);
> + for (j = i; j > 0; --j)
> + IndexQueue.push_back(j - 1);
> +
> + for (auto &k : IndexQueue) {
> + if (R.isConsecutiveAccess(Stores[i], Stores[k], DL)) {
> + Tails.insert(Stores[k]);
> Heads.insert(Stores[i]);
> - ConsecutiveChain[Stores[i]] = Stores[j];
> + ConsecutiveChain[Stores[i]] = Stores[k];
> + break;
> }
> }
> }
> Index: test/Transforms/SLPVectorizer/X86/pr23510.ll
> ===================================================================
> --- test/Transforms/SLPVectorizer/X86/pr23510.ll
> +++ test/Transforms/SLPVectorizer/X86/pr23510.ll
> @@ -0,0 +1,37 @@
> +; PR23510
> +; RUN: opt < %s -basicaa -slp-vectorizer -S | FileCheck %s
> +
> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> +; CHECK: lshr <2 x i64>
> +; CHECK: lshr <2 x i64>
> +
> + at total = global i64 0, align 8
> +
> +define void @_Z3fooPml(i64* nocapture %a, i64 %i) {
> +entry:
> + %tmp = load i64, i64* %a, align 8
> + %shr = lshr i64 %tmp, 4
> + store i64 %shr, i64* %a, align 8
> + %arrayidx1 = getelementptr inbounds i64, i64* %a, i64 1
> + %tmp1 = load i64, i64* %arrayidx1, align 8
> + %shr2 = lshr i64 %tmp1, 4
> + store i64 %shr2, i64* %arrayidx1, align 8
> + %arrayidx3 = getelementptr inbounds i64, i64* %a, i64 %i
> + %tmp2 = load i64, i64* %arrayidx3, align 8
> + %tmp3 = load i64, i64* @total, align 8
> + %add = add i64 %tmp3, %tmp2
> + store i64 %add, i64* @total, align 8
> + %tmp4 = load i64, i64* %a, align 8
> + %shr5 = lshr i64 %tmp4, 4
> + store i64 %shr5, i64* %a, align 8
> + %tmp5 = load i64, i64* %arrayidx1, align 8
> + %shr7 = lshr i64 %tmp5, 4
> + store i64 %shr7, i64* %arrayidx1, align 8
> + %tmp6 = load i64, i64* %arrayidx3, align 8
> + %tmp7 = load i64, i64* @total, align 8
> + %add9 = add i64 %tmp7, %tmp6
> + store i64 %add9, i64* @total, align 8
> + ret void
> +}
>
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