[Polly] Allow changing array dims when importing JScop (#174582)

This is in preparation to avoid relying on GEPs to derive dependency
information; Clang will eventually emit `ptradd` instead of
`getelementptr`.

polly/lib/Exchange/JSONExporter.cpp

@@ -542,17 +542,6 @@ static bool areArraysEqual(ScopArrayInfo *SAI, const json::Object &Array) {
   if (SAI->getName() != *Array.getString("name"))
     return false;
 
-  if (SAI->getNumberOfDimensions() != Array.getArray("sizes")->size())
-    return false;
-
-  for (unsigned i = 1; i < Array.getArray("sizes")->size(); i++) {
-    SAI->getDimensionSize(i)->print(RawStringOstream);
-    const json::Array &SizesArray = *Array.getArray("sizes");
-    if (Buffer != SizesArray[i].getAsString().value())
-      return false;
-    Buffer.clear();
-  }
-
   // Check if key 'type' differs from the current one or is not valid.
   SAI->getElementType()->print(RawStringOstream);
   if (Buffer != Array.getString("type").value()) {
@@ -616,10 +605,45 @@ static bool importArrays(Scop &S, const json::Object &JScop) {
       errs() << "Not enough array entries in JScop file.\n";
       return false;
     }
-    if (!areArraysEqual(SAI, *Arrays[ArrayIdx].getAsObject())) {
+    const json::Object &Array = *Arrays[ArrayIdx].getAsObject();
+    if (!areArraysEqual(SAI, Array)) {
       errs() << "No match for array '" << SAI->getName() << "' in JScop.\n";
       return false;
     }
+
+    auto *DimSizeType = Type::getInt64Ty(S.getSE()->getContext());
+    const json::Array &SizesArray = *Array.getArray("sizes");
+
+    SmallVector<const SCEV *> SCEVSizes;
+    for (unsigned i = 0; i < SizesArray.size(); i++) {
+      std::string StrSize = SizesArray[i].getAsString()->str();
+      if (StrSize == "*") {
+        if (i != 0) {
+          errs() << "undefined size only allowed for outermost dimension\n";
+          return false;
+        }
+        SCEVSizes.push_back(nullptr);
+        continue;
+      }
+
+      int Size = std::stoi(StrSize);
+
+      // Check if the size if positive.
+      if (Size <= 0) {
+        errs() << "The size at index " << i << " is =< 0.\n";
+        return false;
+      }
+
+      const SCEV *ScevSize = S.getSE()->getConstant(DimSizeType, Size);
+      SCEVSizes.push_back(ScevSize);
+    }
+
+    // TODO: If changing the dimensionality of an array, all its accesses must
+    //       be updated to that dimensionality. Currently there is no check
+    //       whether all accesses are really updated.
+    if (!SAI->updateSizes(SCEVSizes, /*CheckConsistency=*/false))
+      return false;
+
     ArrayIdx++;
   }
 

polly/test/JSONExporter/ImportAccesses/change-array-dims.ll

@@ -0,0 +1,59 @@
+; RUN: opt %loadNPMPolly '-passes=polly-custom<import-jscop>' -polly-import-jscop-postfix=transformed -polly-print-import-jscop -disable-output < %s | FileCheck %s
+
+define void @change-array-dims(ptr noalias nonnull %A, ptr noalias nonnull %B) {
+entry:
+  br label %outer.preheader
+
+outer.preheader:
+  br label %outer.for
+
+outer.for:
+  %j = phi i32 [0, %outer.preheader], [%j.inc, %outer.inc]
+  %j.cmp = icmp slt i32 %j, 2
+  br i1 %j.cmp, label %inner.preheader, label %outer.exit
+
+
+    inner.preheader:
+      br label %inner.for
+
+    inner.for:
+      %i = phi i32 [0, %inner.preheader], [%i.inc, %inner.inc]
+      br label %body
+
+
+
+        body:
+          %mul = mul nsw i32 %j, 4
+          %add = add nsw i32 %mul, %i
+          %A_idx = getelementptr inbounds double, ptr %A, i32 %add
+          store double 42.0, ptr %A_idx
+          br label %inner.inc
+
+
+
+    inner.inc:
+      %i.inc = add nuw nsw i32 %i, 1
+      %i.cmp = icmp slt i32 %i.inc, 4
+      br i1 %i.cmp, label %inner.for, label %inner.exit
+
+    inner.exit:
+      br label %outer.inc
+
+
+
+outer.inc:
+  %j.inc = add nuw nsw i32 %j, 1
+  br label %outer.for
+
+outer.exit:
+  br label %return
+
+return:
+  ret void
+}
+
+
+; CHECK:      Stmt_body
+; CHECK:          MustWriteAccess :=  [Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:       { Stmt_body[i0, i1] -> MemRef_A[4i0 + i1] };
+; CHECK-NEXT:       new: { Stmt_body[i0, i1] -> MemRef_A[i0, i1] };

polly/test/JSONExporter/ImportAccesses/change-array-dims___%outer.for---%return.jscop

@@ -0,0 +1,26 @@
+{
+   "arrays": [
+      {
+         "name": "MemRef_A",
+         "sizes": [
+            "*"
+         ],
+         "type": "double"
+      }
+   ],
+   "context": "{  :  }",
+   "name": "%outer.for---%return",
+   "statements": [
+      {
+         "accesses": [
+            {
+               "kind": "write",
+               "relation": "{ Stmt_body[i0, i1] -> MemRef_A[4i0 + i1] }"
+            }
+         ],
+         "domain": "{ Stmt_body[i0, i1] : 0 <= i0 <= 1 and 0 <= i1 <= 3 }",
+         "name": "Stmt_body",
+         "schedule": "{ Stmt_body[i0, i1] -> [i0, i1] }"
+      }
+   ]
+}

polly/test/JSONExporter/ImportAccesses/change-array-dims___%outer.for---%return.jscop.transformed

@@ -0,0 +1,27 @@
+{
+   "arrays": [
+      {
+         "name": "MemRef_A",
+         "sizes": [
+            "*",
+            "4"
+         ],
+         "type": "double"
+      }
+   ],
+   "context": "{  :  }",
+   "name": "%outer.for---%return",
+   "statements": [
+      {
+         "accesses": [
+            {
+               "kind": "write",
+               "relation": "{ Stmt_body[i0, i1] -> MemRef_A[i0][i1] }"
+            }
+         ],
+         "domain": "{ Stmt_body[i0, i1] : 0 <= i0 <= 1 and 0 <= i1 <= 3 }",
+         "name": "Stmt_body",
+         "schedule": "{ Stmt_body[i0, i1] -> [i0, i1] }"
+      }
+   ]
+}