[Mlir-commits] [mlir] [mlir][acc] Offload verifier should print variable names (PR #202678)

[Razvan Lupusoru]

https://github.com/razvanlupusoru created https://github.com/llvm/llvm-project/pull/202678

The offload target verifier is used to ensure that all ssa values and symbols have appropriate OpenACC mapping. When this is not the case, an error is shown. However, showing variable names is useful and thus add the functionality since OpenACCSupport has the means to retrieve them.

>From 78c6f89a65afc8d335a2b1de20ecb30b32f941e4 Mon Sep 17 00:00:00 2001
From: Razvan Lupusoru <rlupusoru at nvidia.com>
Date: Tue, 9 Jun 2026 07:50:14 -0700
Subject: [PATCH] [mlir][acc] Offload verifier should print variable names

The offload target verifier is used to ensure that all ssa values
and symbols have appropriate OpenACC mapping. When this is not the
case, an error is shown. However, showing variable names is useful
and thus add the functionality since OpenACCSupport has the means
to retrieve them.
---
 .../Transforms/OffloadTargetVerifier.cpp      | 38 ++++++++++++++++---
 .../OpenACC/offload-target-verifier.mlir      | 16 ++++++++
 2 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/mlir/lib/Dialect/OpenACC/Transforms/OffloadTargetVerifier.cpp b/mlir/lib/Dialect/OpenACC/Transforms/OffloadTargetVerifier.cpp
index 91a7c7d6489a4..b902e3f15aec1 100644
--- a/mlir/lib/Dialect/OpenACC/Transforms/OffloadTargetVerifier.cpp
+++ b/mlir/lib/Dialect/OpenACC/Transforms/OffloadTargetVerifier.cpp
@@ -118,6 +118,17 @@ class OffloadTargetVerifier
     return invalidSymsList;
   }
 
+  /// Retrieve variable names for the given values.
+  static SmallVector<std::string>
+  getVariableNames(ArrayRef<Value> values,
+                   acc::OpenACCSupport &accSupport) {
+    SmallVector<std::string> names;
+    names.reserve(values.size());
+    for (Value value : values)
+      names.push_back(accSupport.getVariableName(value));
+    return names;
+  }
+
   /// Check if the region has illegal live-in values.
   bool hasIllegalLiveInValues(Operation *regionOp,
                               acc::OpenACCSupport &accSupport) const {
@@ -131,18 +142,33 @@ class OffloadTargetVerifier
     bool hasIllegalValues = !invalidValues.empty();
 
     if (hasIllegalValues) {
+      SmallVector<std::string> invalidVarNames =
+          getVariableNames(invalidValues, accSupport);
+
       if (softCheck) {
         // Emit warnings for each illegal value.
         auto diag = regionOp->emitWarning("offload target verifier: ")
                     << invalidValues.size() << " illegal live-in value(s)";
-        for (auto [idx, invalidValue] : llvm::enumerate(invalidValues)) {
-          diag.attachNote(invalidValue.getLoc()) << "value: " << invalidValue;
+        for (auto [invalidValue, name] :
+             llvm::zip(invalidValues, invalidVarNames)) {
+          if (name.empty()) {
+            diag.attachNote(invalidValue.getLoc()) << "value: " << invalidValue;
+          } else {
+            diag.attachNote(invalidValue.getLoc())
+                << "value: " << invalidValue << ", name: " << name;
+          }
         }
       } else {
-        accSupport.emitNYI(regionOp->getLoc(),
-                           "offload target verifier failed due to " +
-                               Twine(invalidValues.size()) +
-                               " illegal live-in value(s)");
+        std::string message = "offload target verifier failed due to " +
+                              std::to_string(invalidValues.size()) +
+                              " illegal live-in value(s)";
+        SmallVector<std::string> availableVarNames;
+        for (const std::string &name : invalidVarNames)
+          if (!name.empty())
+            availableVarNames.push_back(name);
+        if (!availableVarNames.empty())
+          message += " including: " + llvm::join(availableVarNames, ", ");
+        accSupport.emitNYI(regionOp->getLoc(), message);
       }
     }
 
diff --git a/mlir/test/Dialect/OpenACC/offload-target-verifier.mlir b/mlir/test/Dialect/OpenACC/offload-target-verifier.mlir
index d4380de8e2a31..f004f150cdd37 100644
--- a/mlir/test/Dialect/OpenACC/offload-target-verifier.mlir
+++ b/mlir/test/Dialect/OpenACC/offload-target-verifier.mlir
@@ -31,6 +31,22 @@ func.func @test_memref_f32() {
 
 // -----
 
+// Test memref live-in without data clause - should fail and print var name.
+func.func @test_memref_f32_with_var_name() {
+  // expected-note @below {{, name: my_scalar}}
+  %livein = memref.alloca() {acc.var_name = #acc.var_name<"my_scalar">} : memref<f32>
+  // expected-warning @below {{1 illegal live-in value(s)}}
+  acc.serial {
+    %load = memref.load %livein[] : memref<f32>
+    %accalloca = memref.alloca() : memref<f32>
+    memref.store %load, %accalloca[] : memref<f32>
+    acc.yield
+  }
+  return
+}
+
+// -----
+
 // Test memref with copyin data clause - should pass
 func.func @test_memref_f32_copyin() {
   %alloca = memref.alloca() : memref<f32>