Merge pull request #192 from Xilinx/tiagot.dont_assert_log2_inexact

fix: don't assert when calculating log2 of non-power-of-two number, fail instead.

Author: ttjost

mlir/lib/Dialect/PDL/IR/Builtins.cpp

@@ -85,20 +85,26 @@ LogicalResult static unaryOp(PatternRewriter &rewriter, PDLResultList &results,
 
       results.push_back(rewriter.getIntegerAttr(integerType, resultInt));
     } else if constexpr (T == UnaryOpKind::log2) {
-      auto getIntegerAsAttr = [&](const APSInt &value) {
+      auto getIntegerAsAttr = [&](const APSInt &value) -> Attribute {
+        // Only calculate values for exact log2.
         int32_t log2Value = value.exactLogBase2();
-        assert(log2Value >= 0 &&
-               "log2 of an integer is expected to return an exact integer.");
+        if (log2Value < 0)
+          return Attribute();
         return rewriter.getIntegerAttr(
             integerType,
             APSInt(APInt(bitWidth, log2Value), integerType.isUnsigned()));
       };
       // for log2 we treat signless integer as signed
+      Attribute log2IntegerAttr;
       if (integerType.isSignless())
-        results.push_back(
-            getIntegerAsAttr(APSInt(operandIntAttr.getValue(), false)));
+        log2IntegerAttr =
+            getIntegerAsAttr(APSInt(operandIntAttr.getValue(), false));
       else
-        results.push_back(getIntegerAsAttr(operandIntAttr.getAPSInt()));
+        log2IntegerAttr = getIntegerAsAttr(operandIntAttr.getAPSInt());
+      // Return failure if log2 value isn't exact.
+      if (!log2IntegerAttr)
+        return failure();
+      results.push_back(log2IntegerAttr);
     } else if constexpr (T == UnaryOpKind::abs) {
       if (integerType.isSigned()) {
         // check overflow

mlir/unittests/Dialect/PDL/BuiltinTest.cpp

@@ -613,8 +613,13 @@ TEST_F(BuiltinTest, log2) {
   auto zeroI32 = rewriter.getI32IntegerAttr(0);
   {
     TestPDLResultList results(1);
-    EXPECT_DEATH(static_cast<void>(builtin::log2(rewriter, results, {zeroI32})),
-                 "log2 of an integer is expected to return an exact integer.");
+    EXPECT_FALSE(builtin::log2(rewriter, results, {zeroI32}).succeeded());
+  }
+
+  auto minusOneI32 = rewriter.getI32IntegerAttr(-1);
+  {
+    TestPDLResultList results(1);
+    EXPECT_FALSE(builtin::log2(rewriter, results, {minusOneI32}).succeeded());
   }
 
   auto fourF16 = rewriter.getF16FloatAttr(4.0);