Add target independent standard DMA ops: dma.start, dma.wait

Add target independent standard DMA ops: dma.start, dma.wait. Update pipeline
data transfer to use these to detect DMA ops.

While on this
- return failure from mlir-opt::performActions if a pass generates invalid output
- improve error message for verify 'n' operand traits

PiperOrigin-RevId: 216429885

2 files changed, 17 insertions, 37 deletions

diff --git a/mlir/lib/Transforms/PipelineDataTransfer.cpp b/mlir/lib/Transforms/PipelineDataTransfer.cpp
index 1eeb9a9aa5c..0d025f5678f 100644
--- a/mlir/lib/Transforms/PipelineDataTransfer.cpp
+++ b/mlir/lib/Transforms/PipelineDataTransfer.cpp
@@ -46,34 +46,16 @@ MLFunctionPass *mlir::createPipelineDataTransferPass() {
   return new PipelineDataTransfer();
 }
 
-// Temporary utility: will be replaced when DmaStart/DmaFinish abstract op's or
-// op traits for it are added.  TODO(b/117228571)
-static bool isDmaStartStmt(const OperationStmt &stmt) {
-  return stmt.getName().strref().contains("dma.in.start") ||
-         stmt.getName().strref().contains("dma.out.start");
-}
-
-// Temporary utility: will be replaced when DmaStart/DmaFinish abstract op's are
-// added.  TODO(b/117228571)
-static bool isDmaFinishStmt(const OperationStmt &stmt) {
-  return stmt.getName().strref().contains("dma.finish");
-}
-
 /// Given a DMA start operation, returns the operand position of either the
 /// source or destination memref depending on the one that is at the higher
 /// level of the memory hierarchy.
 // Temporary utility: will be replaced when DmaStart/DmaFinish abstract op's are
 // added.  TODO(b/117228571)
-static unsigned getHigherMemRefPos(const OperationStmt &dmaStartStmt) {
-  assert(isDmaStartStmt(dmaStartStmt));
+static unsigned getHigherMemRefPos(OpPointer<DmaStartOp> dmaStartOp) {
   unsigned srcDmaPos = 0;
-  unsigned destDmaPos =
-      cast<MemRefType>(dmaStartStmt.getOperand(0)->getType())->getRank() + 1;
+  unsigned destDmaPos = dmaStartOp->getSrcMemRefRank() + 1;
 
-  if (cast<MemRefType>(dmaStartStmt.getOperand(srcDmaPos)->getType())
-          ->getMemorySpace() >
-      cast<MemRefType>(dmaStartStmt.getOperand(destDmaPos)->getType())
-          ->getMemorySpace())
+  if (dmaStartOp->getSrcMemorySpace() > dmaStartOp->getDstMemorySpace())
     return srcDmaPos;
   return destDmaPos;
 }
@@ -81,9 +63,9 @@ static unsigned getHigherMemRefPos(const OperationStmt &dmaStartStmt) {
 // Returns the position of the tag memref operand given a DMA statement.
 // Temporary utility: will be replaced when DmaStart/DmaFinish abstract op's are
 // added.  TODO(b/117228571)
-unsigned getTagMemRefPos(const OperationStmt &dmaStmt) {
-  assert(isDmaStartStmt(dmaStmt) || isDmaFinishStmt(dmaStmt));
-  if (isDmaStartStmt(dmaStmt)) {
+static unsigned getTagMemRefPos(const OperationStmt &dmaStmt) {
+  assert(dmaStmt.is<DmaStartOp>() || dmaStmt.is<DmaWaitOp>());
+  if (dmaStmt.is<DmaStartOp>()) {
     // Second to last operand.
     return dmaStmt.getNumOperands() - 2;
   }
@@ -91,7 +73,8 @@ unsigned getTagMemRefPos(const OperationStmt &dmaStmt) {
   return 0;
 }
 
-/// Doubles the buffer of the supplied memref.
+/// Doubles the buffer of the supplied memref while replacing all uses of the
+/// old memref. Returns false if such a replacement cannot be performed.
 static bool doubleBuffer(MLValue *oldMemRef, ForStmt *forStmt) {
   MLFuncBuilder bInner(forStmt, forStmt->begin());
   bInner.setInsertionPoint(forStmt, forStmt->begin());
@@ -130,7 +113,7 @@ static bool doubleBuffer(MLValue *oldMemRef, ForStmt *forStmt) {
   return true;
 }
 
-// For testing purposes, this just runs on the first for statement of an
+// For testing purposes, this just runs on the first 'for' statement of an
 // MLFunction at the top level.
 // TODO(bondhugula): upgrade this to scan all the relevant 'for' statements when
 // the other TODOs listed inside are dealt with.
@@ -158,9 +141,9 @@ PassResult PipelineDataTransfer::runOnMLFunction(MLFunction *f) {
     auto *opStmt = dyn_cast<OperationStmt>(&stmt);
     if (!opStmt)
       continue;
-    if (isDmaStartStmt(*opStmt)) {
+    if (opStmt->is<DmaStartOp>()) {
       dmaStartStmts.push_back(opStmt);
-    } else if (isDmaFinishStmt(*opStmt)) {
+    } else if (opStmt->is<DmaWaitOp>()) {
       dmaFinishStmts.push_back(opStmt);
     }
   }
@@ -182,8 +165,8 @@ PassResult PipelineDataTransfer::runOnMLFunction(MLFunction *f) {
   // A DMA start statement has two memref's - the one from the higher level of
   // memory hierarchy is the one to double buffer.
   for (auto *dmaStartStmt : dmaStartStmts) {
-    MLValue *oldMemRef = cast<MLValue>(
-        dmaStartStmt->getOperand(getHigherMemRefPos(*dmaStartStmt)));
+    MLValue *oldMemRef = cast<MLValue>(dmaStartStmt->getOperand(
+        getHigherMemRefPos(dmaStartStmt->getAs<DmaStartOp>())));
     if (!doubleBuffer(oldMemRef, forStmt))
       return PassResult::Failure;
   }
@@ -208,10 +191,10 @@ PassResult PipelineDataTransfer::runOnMLFunction(MLFunction *f) {
       // TODO(bondhugula): check whether such statements do not have any DMAs
       // nested within.
       opDelayMap[&stmt] = 1;
-    } else if (isDmaStartStmt(*opStmt)) {
+    } else if (opStmt->is<DmaStartOp>()) {
       // DMA starts are not shifted.
       opDelayMap[&stmt] = 0;
-    } else if (isDmaFinishStmt(*opStmt)) {
+    } else if (opStmt->is<DmaWaitOp>()) {
       // DMA finish op shifted by one.
       opDelayMap[&stmt] = 1;
     } else if (!opStmt->is<AffineApplyOp>()) {
diff --git a/mlir/lib/Transforms/Utils.cpp b/mlir/lib/Transforms/Utils.cpp
index cc1c7973858..0262eb94bd7 100644
--- a/mlir/lib/Transforms/Utils.cpp
+++ b/mlir/lib/Transforms/Utils.cpp
@@ -33,12 +33,9 @@ using namespace mlir;
 // Temporary utility: will be replaced when this is modeled through
 // side-effects/op traits. TODO(b/117228571)
 static bool isMemRefDereferencingOp(const Operation &op) {
-  if (op.is<LoadOp>() || op.is<StoreOp>() ||
-      op.getName().strref().contains("dma.in.start") ||
-      op.getName().strref().contains("dma.out.start") ||
-      op.getName().strref().contains("dma.finish")) {
+  if (op.is<LoadOp>() || op.is<StoreOp>() || op.is<DmaStartOp>() ||
+      op.is<DmaWaitOp>())
     return true;
-  }
   return false;
 }