[FIX] Look through div & srem instructions in SCEVs

  The findValues() function did not look through div & srem instructions
  that were part of the argument SCEV. However, in different other
  places we already look through it. This mismatch caused us to preload
  values in the wrong order.

llvm-svn: 265775

diff --git a/polly/include/polly/Support/SCEVValidator.h b/polly/include/polly/Support/SCEVValidator.h
index 4e1351c..b95c667 100644 (file)
--- a/polly/include/polly/Support/SCEVValidator.h
+++ b/polly/include/polly/Support/SCEVValidator.h
@@ -37,9 +37,11 @@ void findLoops(const llvm::SCEV *Expr,
 /// @brief Find the values referenced by SCEVUnknowns in a given SCEV
 /// expression.
 ///
-/// @param Expr The SCEV expression to scan for SCEVUnknowns.
-/// @param Expr A vector into which the found values are inserted.
-void findValues(const llvm::SCEV *Expr, llvm::SetVector<llvm::Value *> &Values);
+/// @param Expr   The SCEV expression to scan for SCEVUnknowns.
+/// @param SE     The ScalarEvolution analysis for this function.
+/// @param Values A vector into which the found values are inserted.
+void findValues(const llvm::SCEV *Expr, llvm::ScalarEvolution &SE,
+                llvm::SetVector<llvm::Value *> &Values);
 
 /// Returns true when the SCEV contains references to instructions within the
 /// region.

diff --git a/polly/lib/Analysis/ScopInfo.cpp b/polly/lib/Analysis/ScopInfo.cpp
index ff88536..a56318b 100644 (file)
--- a/polly/lib/Analysis/ScopInfo.cpp
+++ b/polly/lib/Analysis/ScopInfo.cpp
@@ -3063,7 +3063,7 @@ void Scop::addInvariantLoads(ScopStmt &Stmt, MemoryAccessList &InvMAs) {
       SetVector<Value *> Values;
       for (const SCEV *Parameter : Parameters) {
         Values.clear();
-        findValues(Parameter, Values);
+        findValues(Parameter, *SE, Values);
         if (!Values.count(AccInst))
           continue;
 

diff --git a/polly/lib/CodeGen/IslNodeBuilder.cpp b/polly/lib/CodeGen/IslNodeBuilder.cpp
index 3068de4..b21136e 100644 (file)
--- a/polly/lib/CodeGen/IslNodeBuilder.cpp
+++ b/polly/lib/CodeGen/IslNodeBuilder.cpp
@@ -304,7 +304,7 @@ void IslNodeBuilder::getReferencesInSubtree(__isl_keep isl_ast_node *For,
   addReferencesFromStmtUnionSet(Schedule, References);
 
   for (const SCEV *Expr : SCEVs) {
-    findValues(Expr, Values);
+    findValues(Expr, SE, Values);
     findLoops(Expr, Loops);
   }
 
@@ -852,7 +852,7 @@ bool IslNodeBuilder::materializeValue(isl_id *Id) {
     // check if any value refered to in ParamSCEV is an invariant load
     // and if so make sure its equivalence class is preloaded.
     SetVector<Value *> Values;
-    findValues(ParamSCEV, Values);
+    findValues(ParamSCEV, SE, Values);
     for (auto *Val : Values) {
 
       // Check if the value is an instruction in a dead block within the SCoP

diff --git a/polly/lib/Support/SCEVValidator.cpp b/polly/lib/Support/SCEVValidator.cpp
index 0bece55..4b91025 100644 (file)
--- a/polly/lib/Support/SCEVValidator.cpp
+++ b/polly/lib/Support/SCEVValidator.cpp
@@ -560,21 +560,45 @@ void findLoops(const SCEV *Expr, SetVector<const Loop *> &Loops) {
 
 /// Find all values referenced in SCEVUnknowns.
 class SCEVFindValues {
+  ScalarEvolution &SE;
   SetVector<Value *> &Values;
 
 public:
-  SCEVFindValues(SetVector<Value *> &Values) : Values(Values) {}
+  SCEVFindValues(ScalarEvolution &SE, SetVector<Value *> &Values)
+      : SE(SE), Values(Values) {}
 
   bool follow(const SCEV *S) {
-    if (const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(S))
+    const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(S);
+    if (!Unknown)
+      return true;
+
+    Instruction *Inst = dyn_cast<Instruction>(Unknown->getValue());
+    if (!Inst || (Inst->getOpcode() != Instruction::SRem &&
+                  Inst->getOpcode() != Instruction::SDiv)) {
       Values.insert(Unknown->getValue());
-    return true;
+      return false;
+    }
+
+    auto *Dividend = SE.getSCEV(Inst->getOperand(1));
+    if (!isa<SCEVConstant>(Dividend)) {
+      Values.insert(Unknown->getValue());
+      return false;
+    }
+
+    auto *Divisor = SE.getSCEV(Inst->getOperand(0));
+    SCEVFindValues FindValues(SE, Values);
+    SCEVTraversal<SCEVFindValues> ST(FindValues);
+    ST.visitAll(Dividend);
+    ST.visitAll(Divisor);
+
+    return false;
   }
   bool isDone() { return false; }
 };
 
-void findValues(const SCEV *Expr, SetVector<Value *> &Values) {
-  SCEVFindValues FindValues(Values);
+void findValues(const SCEV *Expr, ScalarEvolution &SE,
+                SetVector<Value *> &Values) {
+  SCEVFindValues FindValues(SE, Values);
   SCEVTraversal<SCEVFindValues> ST(FindValues);
   ST.visitAll(Expr);
 }

diff --git a/polly/test/Isl/CodeGen/scev-division-invariant-load.ll b/polly/test/Isl/CodeGen/scev-division-invariant-load.ll
new file mode 100644 (file)
index 0000000..3af47b6
--- /dev/null
+++ b/polly/test/Isl/CodeGen/scev-division-invariant-load.ll
@@ -0,0 +1,51 @@
+; RUN: opt %loadPolly -S -polly-codegen < %s
+;
+; Check that we generate valid code as we did not use the preloaded
+; value of %tmp1 for the access function of the preloaded %tmp4.
+;
+; ModuleID = 'bug.ll'
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+%struct.frame_store = type { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, %struct.picture*, %struct.picture*, %struct.picture* }
+%struct.picture = type { i32, i32, i32, i32, i32, i32, [6 x [33 x i64]], [6 x [33 x i64]], [6 x [33 x i64]], [6 x [33 x i64]], i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i16**, i16*, i16*, i16**, i16**, i16***, i8*, i16***, i64***, i64***, i16****, i8**, i8**, %struct.picture*, %struct.picture*, %struct.picture*, i32, i32, i32, i32, i32, i32, i32 }
+
+define void @dpb_split_field(%struct.frame_store* %fs) {
+entry:
+  br label %for.body544
+
+for.body544:                                      ; preds = %if.end908, %for.body544.lr.ph
+  %indvars.iv87 = phi i64 [ 0, %entry ], [ %indvars.iv.next88, %if.end908 ]
+  %tmp = phi %struct.picture* [ undef, %entry ], [ %tmp6, %if.end908 ]
+  br label %land.lhs.true563
+
+land.lhs.true563:                                 ; preds = %for.body544
+  %size_x551 = getelementptr inbounds %struct.picture, %struct.picture* %tmp, i64 0, i32 18
+  %tmp1 = load i32, i32* %size_x551, align 8
+  %div552 = sdiv i32 %tmp1, 16
+  %tmp2 = trunc i64 %indvars.iv87 to i32
+  %div554 = sdiv i32 %tmp2, 4
+  %mul555 = mul i32 %div552, %div554
+  %tmp9 = add i32 %mul555, 0
+  %tmp10 = shl i32 %tmp9, 1
+  %add559 = add i32 %tmp10, 0
+  %idxprom564 = sext i32 %add559 to i64
+  %mb_field566 = getelementptr inbounds %struct.picture, %struct.picture* %tmp, i64 0, i32 31
+  %tmp3 = load i8*, i8** %mb_field566, align 8
+  %arrayidx567 = getelementptr inbounds i8, i8* %tmp3, i64 %idxprom564
+  %tmp4 = load i8, i8* %arrayidx567, align 1
+  %tobool569 = icmp eq i8 %tmp4, 0
+  br i1 %tobool569, label %if.end908, label %if.then570
+
+if.then570:                                       ; preds = %land.lhs.true563
+  %frame = getelementptr inbounds %struct.frame_store, %struct.frame_store* %fs, i64 0, i32 10
+  %tmp5 = load %struct.picture*, %struct.picture** %frame, align 8
+  br label %if.end908
+
+if.end908:                                        ; preds = %if.then570, %land.lhs.true563
+  %tmp6 = phi %struct.picture* [ %tmp, %land.lhs.true563 ], [ undef, %if.then570 ]
+  %indvars.iv.next88 = add nuw nsw i64 %indvars.iv87, 1
+  br i1 undef, label %for.body544, label %for.inc912
+
+for.inc912:                                       ; preds = %if.end908
+  ret void
+}