[polly] r267707 - [FIX] Propagate execution domain of invariant loads
Tobias Grosser via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 28 22:15:53 PDT 2016
On 04/27/2016 02:49 PM, Johannes Doerfert via llvm-commits wrote:
> Author: jdoerfert
> Date: Wed Apr 27 07:49:11 2016
> New Revision: 267707
>
> URL: http://llvm.org/viewvc/llvm-project?rev=267707&view=rev
> Log:
> [FIX] Propagate execution domain of invariant loads
>
> If the base pointer of an invariant load is is loaded conditionally, that
> condition needs to hold for the invariant load too. The structure of the
> program will imply this for domain constraints but not for imprecisions in
> the modeling. To this end we will propagate the execution context of base
> pointers during code generation and thus ensure the derived pointer does
> not access an invalid base pointer.
Hi Johannes,
this patch fixed the original bug, but seems to have introduced a new one:
http://lab.llvm.org:8011/builders/perf-x86_64-penryn-O3-polly-before-vectorizer-unprofitable/builds/1792
Best,
Tobias
>
> Added:
> polly/trunk/test/Isl/CodeGen/invariant_load_base_pointer_conditional_2.ll
> Modified:
> polly/trunk/include/polly/CodeGen/IslNodeBuilder.h
> polly/trunk/include/polly/ScopInfo.h
> polly/trunk/lib/Analysis/ScopInfo.cpp
> polly/trunk/lib/CodeGen/IslNodeBuilder.cpp
>
> Modified: polly/trunk/include/polly/CodeGen/IslNodeBuilder.h
> URL: http://llvm.org/viewvc/llvm-project/polly/trunk/include/polly/CodeGen/IslNodeBuilder.h?rev=267707&r1=267706&r2=267707&view=diff
> ==============================================================================
> --- polly/trunk/include/polly/CodeGen/IslNodeBuilder.h (original)
> +++ polly/trunk/include/polly/CodeGen/IslNodeBuilder.h Wed Apr 27 07:49:11 2016
> @@ -247,7 +247,7 @@ protected:
> /// to the required type.
> ///
> /// @returns False, iff a problem occured and the load was not preloaded.
> - bool preloadInvariantEquivClass(const InvariantEquivClassTy &IAClass);
> + bool preloadInvariantEquivClass(InvariantEquivClassTy &IAClass);
>
> void createForVector(__isl_take isl_ast_node *For, int VectorWidth);
> void createForSequential(__isl_take isl_ast_node *For, bool KnownParallel);
>
> Modified: polly/trunk/include/polly/ScopInfo.h
> URL: http://llvm.org/viewvc/llvm-project/polly/trunk/include/polly/ScopInfo.h?rev=267707&r1=267706&r2=267707&view=diff
> ==============================================================================
> --- polly/trunk/include/polly/ScopInfo.h (original)
> +++ polly/trunk/include/polly/ScopInfo.h Wed Apr 27 07:49:11 2016
> @@ -1895,10 +1895,10 @@ public:
> inline unsigned getMaxLoopDepth() const { return MaxLoopDepth; }
>
> /// @brief Return the invariant equivalence class for @p Val if any.
> - const InvariantEquivClassTy *lookupInvariantEquivClass(Value *Val) const;
> + InvariantEquivClassTy *lookupInvariantEquivClass(Value *Val);
>
> /// @brief Return the set of invariant accesses.
> - const InvariantEquivClassesTy &getInvariantAccesses() const {
> + InvariantEquivClassesTy &getInvariantAccesses() {
> return InvariantEquivClasses;
> }
>
>
> Modified: polly/trunk/lib/Analysis/ScopInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopInfo.cpp?rev=267707&r1=267706&r2=267707&view=diff
> ==============================================================================
> --- polly/trunk/lib/Analysis/ScopInfo.cpp (original)
> +++ polly/trunk/lib/Analysis/ScopInfo.cpp Wed Apr 27 07:49:11 2016
> @@ -3221,7 +3221,7 @@ void Scop::simplifySCoP(bool RemoveIgnor
> }
> }
>
> -const InvariantEquivClassTy *Scop::lookupInvariantEquivClass(Value *Val) const {
> +InvariantEquivClassTy *Scop::lookupInvariantEquivClass(Value *Val) {
> LoadInst *LInst = dyn_cast<LoadInst>(Val);
> if (!LInst)
> return nullptr;
>
> Modified: polly/trunk/lib/CodeGen/IslNodeBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/CodeGen/IslNodeBuilder.cpp?rev=267707&r1=267706&r2=267707&view=diff
> ==============================================================================
> --- polly/trunk/lib/CodeGen/IslNodeBuilder.cpp (original)
> +++ polly/trunk/lib/CodeGen/IslNodeBuilder.cpp Wed Apr 27 07:49:11 2016
> @@ -888,7 +888,7 @@ bool IslNodeBuilder::materializeValue(is
> }
> }
>
> - if (const auto *IAClass = S.lookupInvariantEquivClass(Val)) {
> + if (auto *IAClass = S.lookupInvariantEquivClass(Val)) {
>
> // Check if this invariant access class is empty, hence if we never
> // actually added a loads instruction to it. In that case it has no
> @@ -1035,7 +1035,7 @@ Value *IslNodeBuilder::preloadInvariantL
> }
>
> bool IslNodeBuilder::preloadInvariantEquivClass(
> - const InvariantEquivClassTy &IAClass) {
> + InvariantEquivClassTy &IAClass) {
> // For an equivalence class of invariant loads we pre-load the representing
> // element with the unified execution context. However, we have to map all
> // elements of the class to the one preloaded load as they are referenced
> @@ -1059,18 +1059,26 @@ bool IslNodeBuilder::preloadInvariantEqu
> if (!PreloadedPtrs.insert(PtrId).second)
> return false;
>
> + // The exectution context of the IAClass.
> + isl_set *&ExecutionCtx = std::get<2>(IAClass);
> +
> // If the base pointer of this class is dependent on another one we have to
> // make sure it was preloaded already.
> auto *SAI = MA->getScopArrayInfo();
> - if (const auto *BaseIAClass = S.lookupInvariantEquivClass(SAI->getBasePtr()))
> + if (auto *BaseIAClass = S.lookupInvariantEquivClass(SAI->getBasePtr())) {
> if (!preloadInvariantEquivClass(*BaseIAClass))
> return false;
>
> + // After we preloaded the BaseIAClass we adjusted the BaseExecutionCtx and
> + // we need to refine the ExecutionCtx.
> + isl_set *BaseExecutionCtx = isl_set_copy(std::get<2>(*BaseIAClass));
> + ExecutionCtx = isl_set_intersect(ExecutionCtx, BaseExecutionCtx);
> + }
> +
> Instruction *AccInst = MA->getAccessInstruction();
> Type *AccInstTy = AccInst->getType();
>
> - isl_set *Domain = isl_set_copy(std::get<2>(IAClass));
> - Value *PreloadVal = preloadInvariantLoad(*MA, Domain);
> + Value *PreloadVal = preloadInvariantLoad(*MA, isl_set_copy(ExecutionCtx));
> if (!PreloadVal)
> return false;
>
> @@ -1138,7 +1146,7 @@ bool IslNodeBuilder::preloadInvariantEqu
>
> bool IslNodeBuilder::preloadInvariantLoads() {
>
> - const auto &InvariantEquivClasses = S.getInvariantAccesses();
> + auto &InvariantEquivClasses = S.getInvariantAccesses();
> if (InvariantEquivClasses.empty())
> return true;
>
> @@ -1147,7 +1155,7 @@ bool IslNodeBuilder::preloadInvariantLoa
> PreLoadBB->setName("polly.preload.begin");
> Builder.SetInsertPoint(&PreLoadBB->front());
>
> - for (const auto &IAClass : InvariantEquivClasses)
> + for (auto &IAClass : InvariantEquivClasses)
> if (!preloadInvariantEquivClass(IAClass))
> return false;
>
>
> Added: polly/trunk/test/Isl/CodeGen/invariant_load_base_pointer_conditional_2.ll
> URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/Isl/CodeGen/invariant_load_base_pointer_conditional_2.ll?rev=267707&view=auto
> ==============================================================================
> --- polly/trunk/test/Isl/CodeGen/invariant_load_base_pointer_conditional_2.ll (added)
> +++ polly/trunk/test/Isl/CodeGen/invariant_load_base_pointer_conditional_2.ll Wed Apr 27 07:49:11 2016
> @@ -0,0 +1,73 @@
> +; RUN: opt %loadPolly -analyze -polly-scops < %s | FileCheck %s
> +; RUN: opt %loadPolly -S -polly-codegen < %s | FileCheck %s --check-prefix=IR
> +;
> +; As (p + q) can overflow we have to check that we load from
> +; I[p + q] only if it does not.
> +;
> +; CHECK: Invariant Accesses: {
> +; CHECK-NEXT: ReadAccess := [Reduction Type: NONE] [Scalar: 0]
> +; CHECK-NEXT: [N, p, q] -> { Stmt_for_body[i0] -> MemRef_I[p + q] };
> +; CHECK-NEXT: Execution Context: [N, p, q] -> { : N > 0 and -2147483648 - p <= q <= 2147483647 - p }
> +; CHECK-NEXT: ReadAccess := [Reduction Type: NONE] [Scalar: 0]
> +; CHECK-NEXT: [N, p, q] -> { Stmt_for_body[i0] -> MemRef_tmp1[0] };
> +; CHECK-NEXT: Execution Context: [N, p, q] -> { : N > 0 }
> +; CHECK-NEXT: }
> +;
> +; IR: polly.preload.merge:
> +; IR-NEXT: %polly.preload.tmp1.merge = phi i32* [ %polly.access.I.load, %polly.preload.exec ], [ null, %polly.preload.cond ]
> +; IR-NEXT: store i32* %polly.preload.tmp1.merge, i32** %tmp1.preload.s2a
> +; IR-NEXT: %12 = sext i32 %N to i64
> +; IR-NEXT: %13 = icmp sge i64 %12, 1
> +; IR-NEXT: %14 = sext i32 %q to i64
> +; IR-NEXT: %15 = sext i32 %p to i64
> +; IR-NEXT: %16 = add nsw i64 %15, %14
> +; IR-NEXT: %17 = icmp sle i64 %16, 2147483647
> +; IR-NEXT: %18 = and i1 %13, %17
> +; IR-NEXT: %19 = sext i32 %q to i64
> +; IR-NEXT: %20 = sext i32 %p to i64
> +; IR-NEXT: %21 = add nsw i64 %20, %19
> +; IR-NEXT: %22 = icmp sge i64 %21, -2147483648
> +; IR-NEXT: %23 = and i1 %18, %22
> +; IR-NEXT: br label %polly.preload.cond1
> +;
> +; IR: polly.preload.cond1:
> +; IR-NEXT: br i1 %23
> +;
> +; IR: polly.preload.exec3:
> +; IR-NEXT: %polly.access.polly.preload.tmp1.merge = getelementptr i32, i32* %polly.preload.tmp1.merge, i64 0
> +; IR-NEXT: %polly.access.polly.preload.tmp1.merge.load = load i32, i32* %polly.access.polly.preload.tmp1.merge, align 4
> +;
> +; void f(int **I, int *A, int N, int p, int q) {
> +; for (int i = 0; i < N; i++)
> +; A[i] = *(I[p + q]);
> +; }
> +;
> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> +
> +define void @f(i32** %I, i32* %A, i32 %N, i32 %p, i32 %q) {
> +entry:
> + %tmp = sext i32 %N to i64
> + br label %for.cond
> +
> +for.cond: ; preds = %for.inc, %entry
> + %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
> + %cmp = icmp slt i64 %indvars.iv, %tmp
> + br i1 %cmp, label %for.body, label %for.end
> +
> +for.body: ; preds = %for.cond
> + %add = add i32 %p, %q
> + %idxprom = sext i32 %add to i64
> + %arrayidx = getelementptr inbounds i32*, i32** %I, i64 %idxprom
> + %tmp1 = load i32*, i32** %arrayidx, align 8
> + %tmp2 = load i32, i32* %tmp1, align 4
> + %arrayidx2 = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
> + store i32 %tmp2, i32* %arrayidx2, align 4
> + br label %for.inc
> +
> +for.inc: ; preds = %for.body
> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> + br label %for.cond
> +
> +for.end: ; preds = %for.cond
> + ret void
> +}
>
>
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