[SCEV][LAA] Add tests for SCEV expression transformations performed during LAA

Summary:
Add a print method to Predicated Scalar Evolution which prints all interesting
transformations done by PSE.

Loop Access Analysis will now print this as part of the analysis output.
We now use this to check the exact expression transformations that were done
by PSE in LAA.

The additional checking also acts as white-box testing for the getAsAddRec method.

Reviewers: anemet, sanjoy

Subscribers: sanjoy, mzolotukhin, llvm-commits

Differential Revision: http://reviews.llvm.org/D18792

llvm-svn: 266334

diff --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 974a96e..052a704 100644 (file)
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -1691,6 +1691,9 @@ namespace llvm {
     ScalarEvolution *getSE() const { return &SE; }
     /// We need to explicitly define the copy constructor because of FlagsMap.
     PredicatedScalarEvolution(const PredicatedScalarEvolution&);
+    /// Print the SCEV mappings done by the Predicated Scalar Evolution.
+    /// The printed text is indented by \p Depth.
+    void print(raw_ostream &OS, unsigned Depth) const;
   private:
     /// \brief Increments the version number of the predicate.
     /// This needs to be called every time the SCEV predicate changes.

diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index d1eac46..222005f 100644 (file)
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1904,6 +1904,11 @@ void LoopAccessInfo::print(raw_ostream &OS, unsigned Depth) const {
 
   OS.indent(Depth) << "SCEV assumptions:\n";
   PSE.getUnionPredicate().print(OS, Depth);
+
+  OS << "\n";
+
+  OS.indent(Depth) << "Expressions re-written:\n";
+  PSE.print(OS, Depth);
 }
 
 const LoopAccessInfo &

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 835668a..a05c2b9 100644 (file)
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -10364,3 +10364,26 @@ PredicatedScalarEvolution::PredicatedScalarEvolution(
   for (auto I = Init.FlagsMap.begin(), E = Init.FlagsMap.end(); I != E; ++I)
     FlagsMap.insert(*I);
 }
+
+void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const {
+  // For each block.
+  for (auto *BB : L.getBlocks())
+    for (auto &I : *BB) {
+      if (!SE.isSCEVable(I.getType()))
+        continue;
+
+      auto *Expr = SE.getSCEV(&I);
+      auto II = RewriteMap.find(Expr);
+
+      if (II == RewriteMap.end())
+        continue;
+
+      // Don't print things that are not interesting.
+      if (II->second.second == Expr)
+        continue;
+
+      OS.indent(Depth) << "[PSE]" << I << ":\n";
+      OS.indent(Depth + 2) << *Expr << "\n";
+      OS.indent(Depth + 2) << "--> " << *II->second.second << "\n";
+    }
+}

diff --git a/llvm/test/Analysis/LoopAccessAnalysis/wrapping-pointer-versioning.ll b/llvm/test/Analysis/LoopAccessAnalysis/wrapping-pointer-versioning.ll
index 038a0e3..ee9078c 100644 (file)
--- a/llvm/test/Analysis/LoopAccessAnalysis/wrapping-pointer-versioning.ll
+++ b/llvm/test/Analysis/LoopAccessAnalysis/wrapping-pointer-versioning.ll
@@ -31,6 +31,11 @@ target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 ; We have added the nusw flag to turn this expression into the SCEV expression:
 ;    i64 {0,+,2}<%for.body>
 
+; LAA: [PSE]  %arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext:
+; LAA-NEXT: ((2 * (zext i32 {0,+,2}<%for.body> to i64)) + %a)
+; LAA-NEXT: --> {%a,+,4}<%for.body>
+
+
 ; LV-LABEL: f1
 ; LV-LABEL: for.body.lver.check
 ; LV: [[PredCheck0:%[^ ]*]] = icmp ne i128
@@ -100,6 +105,10 @@ for.end:                                          ; preds = %for.body
 ; We have added the nusw flag to turn this expression into the following SCEV:
 ;     i64 {zext i32 (2 * (trunc i64 %N to i32)) to i64,+,-2}<%for.body>
 
+; LAA: [PSE]  %arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext:
+; LAA-NEXT: ((2 * (zext i32 {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> to i64)) + %a)
+; LAA-NEXT: --> {((2 * (zext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body>
+
 ; LV-LABEL: f2
 ; LV-LABEL: for.body.lver.check
 ; LV: [[PredCheck0:%[^ ]*]] = icmp ne i128
@@ -154,6 +163,10 @@ for.end:                                          ; preds = %for.body
 ; We have added the nssw flag to turn this expression into the following SCEV:
 ;     i64 {0,+,2}<%for.body>
 
+; LAA: [PSE]  %arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext:
+; LAA-NEXT: ((2 * (sext i32 {0,+,2}<%for.body> to i64)) + %a)
+; LAA-NEXT: --> {%a,+,4}<%for.body>
+
 ; LV-LABEL: f3
 ; LV-LABEL: for.body.lver.check
 ; LV: [[PredCheck0:%[^ ]*]] = icmp ne i128
@@ -204,6 +217,10 @@ for.end:                                          ; preds = %for.body
 ; We have added the nssw flag to turn this expression into the following SCEV:
 ;     i64 {sext i32 (2 * (trunc i64 %N to i32)) to i64,+,-2}<%for.body>
 
+; LAA: [PSE]  %arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext:
+; LAA-NEXT: ((2 * (sext i32 {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> to i64)) + %a)
+; LAA-NEXT: --> {((2 * (sext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body>
+
 ; LV-LABEL: f4
 ; LV-LABEL: for.body.lver.check
 ; LV: [[PredCheck0:%[^ ]*]] = icmp ne i128
@@ -257,6 +274,10 @@ for.end:                                          ; preds = %for.body
 ; LAA-NEXT: {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> Added Flags: <nssw>
 ; LAA-NEXT: {((2 * (sext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body> Added Flags: <nusw>
 
+; LAA: [PSE]  %arrayidxA = getelementptr inbounds i16, i16* %a, i32 %mul:
+; LAA-NEXT: ((2 * (sext i32 {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> to i64))<nsw> + %a)<nsw>
+; LAA-NEXT: --> {((2 * (sext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body>
+
 ; LV-LABEL: f5
 ; LV-LABEL: for.body.lver.check
 define void @f5(i16* noalias %a,