[polly] r308876 - [ForwardOpTree] Support read-only value uses.
Michael Kruse via llvm-commits
llvm-commits at lists.llvm.org
Mon Jul 24 05:43:27 PDT 2017
Author: meinersbur
Date: Mon Jul 24 05:43:27 2017
New Revision: 308876
URL: http://llvm.org/viewvc/llvm-project?rev=308876&view=rev
Log:
[ForwardOpTree] Support read-only value uses.
Read-only values (values defined before the SCoP) require special
handing with -polly-analyze-read-only-scalars=true (which is the
default). If active, each use of a value requires a read access.
When a copied value uses a read-only value, we must also ensure that
such a MemoryAccess is available or is created.
Differential Revision: https://reviews.llvm.org/D35764
Added:
polly/trunk/test/ForwardOpTree/forward_readonly.ll
Modified:
polly/trunk/include/polly/ScopBuilder.h
polly/trunk/include/polly/ScopInfo.h
polly/trunk/lib/Analysis/ScopBuilder.cpp
polly/trunk/lib/Analysis/ScopInfo.cpp
polly/trunk/lib/Transform/ForwardOpTree.cpp
Modified: polly/trunk/include/polly/ScopBuilder.h
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/include/polly/ScopBuilder.h?rev=308876&r1=308875&r2=308876&view=diff
==============================================================================
--- polly/trunk/include/polly/ScopBuilder.h (original)
+++ polly/trunk/include/polly/ScopBuilder.h Mon Jul 24 05:43:27 2017
@@ -21,6 +21,9 @@
namespace polly {
+/// Command line switch whether to model read-only accesses.
+extern bool ModelReadOnlyScalars;
+
/// Build the Polly IR (Scop and ScopStmt) on a Region.
class ScopBuilder {
//===-------------------------------------------------------------------===//
Modified: polly/trunk/include/polly/ScopInfo.h
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/include/polly/ScopInfo.h?rev=308876&r1=308875&r2=308876&view=diff
==============================================================================
--- polly/trunk/include/polly/ScopInfo.h (original)
+++ polly/trunk/include/polly/ScopInfo.h Mon Jul 24 05:43:27 2017
@@ -1628,6 +1628,18 @@ public:
///
void printInstructions(raw_ostream &OS) const;
+ /// Check whether there is a value read access for @p V in this statement, and
+ /// if not, create one.
+ ///
+ /// This allows to add MemoryAccesses after the initial creation of the Scop
+ /// by ScopBuilder.
+ ///
+ /// @return The already existing or newly created MemoryKind::Value READ
+ /// MemoryAccess.
+ ///
+ /// @see ScopBuilder::ensureValueRead(Value*,ScopStmt*)
+ MemoryAccess *ensureValueRead(Value *V);
+
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
/// Print the ScopStmt to stderr.
void dump() const;
Modified: polly/trunk/lib/Analysis/ScopBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopBuilder.cpp?rev=308876&r1=308875&r2=308876&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopBuilder.cpp (original)
+++ polly/trunk/lib/Analysis/ScopBuilder.cpp Mon Jul 24 05:43:27 2017
@@ -32,10 +32,12 @@ STATISTIC(RichScopFound, "Number of Scop
STATISTIC(InfeasibleScops,
"Number of SCoPs with statically infeasible context.");
-static cl::opt<bool> ModelReadOnlyScalars(
+bool polly::ModelReadOnlyScalars;
+static cl::opt<bool, true> XModelReadOnlyScalars(
"polly-analyze-read-only-scalars",
cl::desc("Model read-only scalar values in the scop description"),
- cl::Hidden, cl::ZeroOrMore, cl::init(true), cl::cat(PollyCategory));
+ cl::location(ModelReadOnlyScalars), cl::Hidden, cl::ZeroOrMore,
+ cl::init(true), cl::cat(PollyCategory));
static cl::opt<bool> UnprofitableScalarAccs(
"polly-unprofitable-scalar-accs",
@@ -778,6 +780,15 @@ void ScopBuilder::ensureValueWrite(Instr
}
void ScopBuilder::ensureValueRead(Value *V, ScopStmt *UserStmt) {
+ // TODO: Make ScopStmt::ensureValueRead(Value*) offer the same functionality
+ // to be able to replace this one. Currently, there is a split responsibility.
+ // In a first step, the MemoryAccess is created, but without the
+ // AccessRelation. In the second step by ScopStmt::buildAccessRelations(), the
+ // AccessRelation is created. At least for scalar accesses, there is no new
+ // information available at ScopStmt::buildAccessRelations(), so we could
+ // create the AccessRelation right away. This is what
+ // ScopStmt::ensureValueRead(Value*) does.
+
auto *Scope = UserStmt->getSurroundingLoop();
auto VUse = VirtualUse::create(scop.get(), UserStmt, Scope, V, false);
switch (VUse.getKind()) {
Modified: polly/trunk/lib/Analysis/ScopInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopInfo.cpp?rev=308876&r1=308875&r2=308876&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopInfo.cpp (original)
+++ polly/trunk/lib/Analysis/ScopInfo.cpp Mon Jul 24 05:43:27 2017
@@ -2042,6 +2042,22 @@ void ScopStmt::removeSingleMemoryAccess(
}
}
+MemoryAccess *ScopStmt::ensureValueRead(Value *V) {
+ MemoryAccess *Access = lookupInputAccessOf(V);
+ if (Access)
+ return Access;
+
+ ScopArrayInfo *SAI =
+ Parent.getOrCreateScopArrayInfo(V, V->getType(), {}, MemoryKind::Value);
+ Access = new MemoryAccess(this, nullptr, MemoryAccess::READ, V, V->getType(),
+ true, {}, {}, V, MemoryKind::Value);
+ Parent.addAccessFunction(Access);
+ Access->buildAccessRelation(SAI);
+ addAccess(Access);
+ Parent.addAccessData(Access);
+ return Access;
+}
+
raw_ostream &polly::operator<<(raw_ostream &O, const ScopStmt &S) {
S.print(O, PollyPrintInstructions);
return O;
Modified: polly/trunk/lib/Transform/ForwardOpTree.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Transform/ForwardOpTree.cpp?rev=308876&r1=308875&r2=308876&view=diff
==============================================================================
--- polly/trunk/lib/Transform/ForwardOpTree.cpp (original)
+++ polly/trunk/lib/Transform/ForwardOpTree.cpp Mon Jul 24 05:43:27 2017
@@ -13,6 +13,7 @@
#include "polly/ForwardOpTree.h"
+#include "polly/ScopBuilder.h"
#include "polly/ScopInfo.h"
#include "polly/ScopPass.h"
#include "polly/Support/GICHelper.h"
@@ -25,6 +26,7 @@ using namespace polly;
using namespace llvm;
STATISTIC(TotalInstructionsCopied, "Number of copied instructions");
+STATISTIC(TotalReadOnlyCopied, "Number of copied read-only accesses");
STATISTIC(TotalForwardedTrees, "Number of forwarded operand trees");
STATISTIC(TotalModifiedStmts,
"Number of statements with at least one forwarded tree");
@@ -37,6 +39,7 @@ namespace {
enum ForwardingDecision {
FD_CannotForward,
FD_CanForward,
+ FD_CanForwardTree,
FD_DidForward,
};
@@ -58,6 +61,9 @@ private:
/// How many instructions have been copied to other statements.
int NumInstructionsCopied = 0;
+ /// How many read-only accesses have been copied.
+ int NumReadOnlyCopied = 0;
+
/// How many operand trees have been forwarded.
int NumForwardedTrees = 0;
@@ -71,6 +77,8 @@ private:
OS.indent(Indent) << "Statistics {\n";
OS.indent(Indent + 4) << "Instructions copied: " << NumInstructionsCopied
<< '\n';
+ OS.indent(Indent + 4) << "Read-only accesses copied: " << NumReadOnlyCopied
+ << '\n';
OS.indent(Indent + 4) << "Operand trees forwarded: " << NumForwardedTrees
<< '\n';
OS.indent(Indent + 4) << "Statements with forwarded operand trees: "
@@ -132,9 +140,16 @@ private:
return FD_CannotForward;
case VirtualUse::ReadOnly:
- // Not supported yet.
- DEBUG(dbgs() << " Cannot forward read-only val: " << *UseVal << "\n");
- return FD_CannotForward;
+ if (!DoIt)
+ return FD_CanForward;
+
+ // If we model read-only scalars, we need to create a MemoryAccess for it.
+ if (ModelReadOnlyScalars)
+ TargetStmt->ensureValueRead(UseVal);
+
+ NumReadOnlyCopied++;
+ TotalReadOnlyCopied++;
+ return FD_DidForward;
case VirtualUse::Intra:
case VirtualUse::Inter:
@@ -183,6 +198,7 @@ private:
return FD_CannotForward;
case FD_CanForward:
+ case FD_CanForwardTree:
assert(!DoIt);
break;
@@ -194,7 +210,7 @@ private:
if (DoIt)
return FD_DidForward;
- return FD_CanForward;
+ return FD_CanForwardTree;
}
llvm_unreachable("Case unhandled");
@@ -211,7 +227,7 @@ private:
ForwardingDecision Assessment =
canForwardTree(Stmt, RA->getAccessValue(), Stmt, InLoop, false);
assert(Assessment != FD_DidForward);
- if (Assessment == FD_CannotForward)
+ if (Assessment != FD_CanForwardTree)
return false;
ForwardingDecision Execution =
Added: polly/trunk/test/ForwardOpTree/forward_readonly.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/ForwardOpTree/forward_readonly.ll?rev=308876&view=auto
==============================================================================
--- polly/trunk/test/ForwardOpTree/forward_readonly.ll (added)
+++ polly/trunk/test/ForwardOpTree/forward_readonly.ll Mon Jul 24 05:43:27 2017
@@ -0,0 +1,84 @@
+; RUN: opt %loadPolly -polly-analyze-read-only-scalars=true -polly-optree -analyze < %s | FileCheck %s -match-full-lines -check-prefixes=STATS,MODEL
+; RUN: opt %loadPolly -polly-analyze-read-only-scalars=false -polly-optree -analyze < %s | FileCheck %s -match-full-lines -check-prefixes=STATS,NOMODEL
+;
+; Move %val to %bodyB, so %bodyA can be removed (by -polly-simplify)
+;
+; for (int j = 0; j < n; j += 1) {
+; bodyA:
+; double val = arg + 21.0;
+;
+; bodyB:
+; A[0] = val;
+; }
+;
+define void @func(i32 %n, double* noalias nonnull %A, double %arg) {
+entry:
+ br label %for
+
+for:
+ %j = phi i32 [0, %entry], [%j.inc, %inc]
+ %j.cmp = icmp slt i32 %j, %n
+ br i1 %j.cmp, label %bodyA, label %exit
+
+ bodyA:
+ %val = fadd double %arg, 21.0
+ br label %bodyB
+
+ bodyB:
+ store double %val, double* %A
+ br label %inc
+
+inc:
+ %j.inc = add nuw nsw i32 %j, 1
+ br label %for
+
+exit:
+ br label %return
+
+return:
+ ret void
+}
+
+
+; STATS: Statistics {
+; STATS: Instructions copied: 1
+; STATS: Read-only accesses copied: 1
+; STATS: Operand trees forwarded: 1
+; STATS: Statements with forwarded operand trees: 1
+; STATS: }
+
+; MODEL: After statements {
+; MODEL-NEXT: Stmt_bodyA
+; MODEL-NEXT: ReadAccess := [Reduction Type: NONE] [Scalar: 1]
+; MODEL-NEXT: [n] -> { Stmt_bodyA[i0] -> MemRef_arg[] };
+; MODEL-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 1]
+; MODEL-NEXT: [n] -> { Stmt_bodyA[i0] -> MemRef_val[] };
+; MODEL-NEXT: Instructions {
+; MODEL-NEXT: %val = fadd double %arg, 2.100000e+01
+; MODEL-NEXT: }
+; MODEL-NEXT: Stmt_bodyB
+; MODEL-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 0]
+; MODEL-NEXT: [n] -> { Stmt_bodyB[i0] -> MemRef_A[0] };
+; MODEL-NEXT: ReadAccess := [Reduction Type: NONE] [Scalar: 1]
+; MODEL-NEXT: [n] -> { Stmt_bodyB[i0] -> MemRef_arg[] };
+; MODEL-NEXT: Instructions {
+; MODEL-NEXT: %val = fadd double %arg, 2.100000e+01
+; MODEL-NEXT: store double %val, double* %A
+; MODEL-NEXT: }
+; MODEL-NEXT: }
+
+; NOMODEL: After statements {
+; NOMODEL-NEXT: Stmt_bodyA
+; NOMODEL-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 1]
+; NOMODEL-NEXT: [n] -> { Stmt_bodyA[i0] -> MemRef_val[] };
+; NOMODEL-NEXT: Instructions {
+; NOMODEL-NEXT: %val = fadd double %arg, 2.100000e+01
+; NOMODEL-NEXT: }
+; NOMODEL-NEXT: Stmt_bodyB
+; NOMODEL-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 0]
+; NOMODEL-NEXT: [n] -> { Stmt_bodyB[i0] -> MemRef_A[0] };
+; NOMODEL-NEXT: Instructions {
+; NOMODEL-NEXT: %val = fadd double %arg, 2.100000e+01
+; NOMODEL-NEXT: store double %val, double* %A
+; NOMODEL-NEXT: }
+; NOMODEL-NEXT: }
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