From 12e31761ce24a4dd7cd6f9c1991058c93c139488 Mon Sep 17 00:00:00 2001
From: Andy Davis <andydavis@google.com>
Date: Thu, 16 May 2019 16:50:35 -0700
Subject: [PATCH]     Fixes a small bug in computing dependence direction
 vectors, where equality constraint can be created on the wrong loop IVs when
 source/sink of the dependence are at different loop depths. Adds unit tests
 for cases where source/sink of the dependence are at varying loop depths.

--

PiperOrigin-RevId: 248627490
---
 mlir/lib/Analysis/AffineAnalysis.cpp              |  5 ++-
 mlir/test/Transforms/memref-dependence-check.mlir | 54 +++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/mlir/lib/Analysis/AffineAnalysis.cpp b/mlir/lib/Analysis/AffineAnalysis.cpp
index 861c0a1..a9dce13 100644
--- a/mlir/lib/Analysis/AffineAnalysis.cpp
+++ b/mlir/lib/Analysis/AffineAnalysis.cpp
@@ -637,11 +637,14 @@ static void computeDirectionVector(
   // variable at column 'j' to the 'dst' IV minus the 'src IV.
   SmallVector<int64_t, 4> eq;
   eq.resize(dependenceDomain->getNumCols());
+  unsigned numSrcDims = srcDomain.getNumDimIds();
+  // Constraint variables format:
+  // [num-common-loops][num-src-dim-ids][num-dst-dim-ids][num-symbols][constant]
   for (unsigned j = 0; j < numCommonLoops; ++j) {
     std::fill(eq.begin(), eq.end(), 0);
     eq[j] = 1;
     eq[j + numCommonLoops] = 1;
-    eq[j + 2 * numCommonLoops] = -1;
+    eq[j + numCommonLoops + numSrcDims] = -1;
     dependenceDomain->addEquality(eq);
   }
 
diff --git a/mlir/test/Transforms/memref-dependence-check.mlir b/mlir/test/Transforms/memref-dependence-check.mlir
index d37a58e..a4dda54 100644
--- a/mlir/test/Transforms/memref-dependence-check.mlir
+++ b/mlir/test/Transforms/memref-dependence-check.mlir
@@ -850,3 +850,57 @@ func @strided_loop_with_loop_carried_dependence_at_depth1() {
   }
   return
 }
+
+// -----
+
+// Test that the loop carried dependence from load to store on '%i0' is
+// properly computed when the load and store are at different loop depths.
+// CHECK-LABEL: func @test_dep_store_depth1_load_depth2
+func @test_dep_store_depth1_load_depth2() {
+  %0 = alloc() : memref<100xf32>
+  %cst = constant 7.000000e+00 : f32
+  affine.for %i0 = 0 to 10 {
+    %a0 = affine.apply (d0) -> (d0 - 1)(%i0)
+    store %cst, %0[%a0] : memref<100xf32>
+    // expected-remark@-1 {{dependence from 0 to 0 at depth 1 = false}}
+    // expected-remark@-2 {{dependence from 0 to 0 at depth 2 = false}}
+    // expected-remark@-3 {{dependence from 0 to 1 at depth 1 = false}}
+    // expected-remark@-4 {{dependence from 0 to 1 at depth 2 = false}}
+    affine.for %i1 = (d0) -> (d0)(%i0) to (d0) -> (d0 + 1)(%i0) {
+      %1 = load %0[%i1] : memref<100xf32>
+      // expected-remark@-1 {{dependence from 1 to 0 at depth 1 = [1, 1]}}
+      // expected-remark@-2 {{dependence from 1 to 0 at depth 2 = false}}
+      // expected-remark@-3 {{dependence from 1 to 1 at depth 1 = false}}
+      // expected-remark@-4 {{dependence from 1 to 1 at depth 2 = false}}
+      // expected-remark@-5 {{dependence from 1 to 1 at depth 3 = false}}
+    }
+  }
+  return
+}
+
+// -----
+
+// Test that the loop carried dependence from store to load on '%i0' is
+// properly computed when the load and store are at different loop depths.
+// CHECK-LABEL: func @test_dep_store_depth2_load_depth1
+func @test_dep_store_depth2_load_depth1() {
+  %0 = alloc() : memref<100xf32>
+  %cst = constant 7.000000e+00 : f32
+  affine.for %i0 = 0 to 10 {
+    affine.for %i1 = (d0) -> (d0)(%i0) to (d0) -> (d0 + 1)(%i0) {
+      store %cst, %0[%i1] : memref<100xf32>
+      // expected-remark@-1 {{dependence from 0 to 0 at depth 1 = false}}
+      // expected-remark@-2 {{dependence from 0 to 0 at depth 2 = false}}
+      // expected-remark@-3 {{dependence from 0 to 0 at depth 3 = false}}
+      // expected-remark@-4 {{dependence from 0 to 1 at depth 1 = [2, 2]}}
+      // expected-remark@-5 {{dependence from 0 to 1 at depth 2 = false}}
+    }
+    %a0 = affine.apply (d0) -> (d0 - 2)(%i0)
+    %1 = load %0[%a0] : memref<100xf32>
+    // expected-remark@-1 {{dependence from 1 to 0 at depth 1 = false}}
+    // expected-remark@-2 {{dependence from 1 to 0 at depth 2 = false}}
+    // expected-remark@-3 {{dependence from 1 to 1 at depth 1 = false}}
+    // expected-remark@-4 {{dependence from 1 to 1 at depth 2 = false}}
+  }
+  return
+}
\ No newline at end of file
-- 
2.7.4