[SCEV] forgetValue: support (with-overflow-inst op0, op1) (#98015)

The use-def walk in forgetValue() was skipping instructions with
non-SCEVable types. However, SCEV may look past with.overflow
intrinsics returning aggregates.

Fixes #97586.

1 files changed, 36 insertions, 0 deletions

diff --git a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
index a7b3c5c..a6a5ffd 100644
--- a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
+++ b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -1589,4 +1589,40 @@ TEST_F(ScalarEvolutionsTest, ApplyLoopGuards) {
   });
 }
 
+TEST_F(ScalarEvolutionsTest, ForgetValueWithOverflowInst) {
+  LLVMContext C;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M = parseAssemblyString(
+      "declare { i32, i1 } @llvm.smul.with.overflow.i32(i32, i32) "
+      "define void @foo(i32 %i) { "
+      "entry: "
+      "  br label %loop.body "
+      "loop.body: "
+      "  %iv = phi i32 [ %iv.next, %loop.body ], [ 0, %entry ] "
+      "  %iv.next = add nsw i32 %iv, 1 "
+      "  %call = call {i32, i1} @llvm.smul.with.overflow.i32(i32 %iv, i32 -2) "
+      "  %extractvalue = extractvalue {i32, i1} %call, 0 "
+      "  %cmp = icmp eq i32 %iv.next, 16 "
+      "  br i1 %cmp, label %exit, label %loop.body "
+      "exit: "
+      "  ret void "
+      "} ",
+      Err, C);
+
+  ASSERT_TRUE(M && "Could not parse module?");
+  ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
+
+  runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
+    auto *ExtractValue = getInstructionByName(F, "extractvalue");
+    auto *IV = getInstructionByName(F, "iv");
+
+    auto *ExtractValueScev = SE.getSCEV(ExtractValue);
+    EXPECT_NE(ExtractValueScev, nullptr);
+
+    SE.forgetValue(IV);
+    auto *ExtractValueScevForgotten = SE.getExistingSCEV(ExtractValue);
+    EXPECT_EQ(ExtractValueScevForgotten, nullptr);
+  });
+}
+
 }  // end namespace llvm