[PATCH] D144845: [SCEV][Test] Add test to prove block's guardering condition

[Aleksandr Popov via Phabricator via llvm-commits]

aleksandr.popov created this revision.
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Add test in which SCEV could prove cond(phi), knowing cond(load),
where load is incoming phi value and all incoming values are the same


https://reviews.llvm.org/D144845

Files:
  llvm/unittests/Analysis/ScalarEvolutionTest.cpp


Index: llvm/unittests/Analysis/ScalarEvolutionTest.cpp
===================================================================
--- llvm/unittests/Analysis/ScalarEvolutionTest.cpp
+++ llvm/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -1744,4 +1744,53 @@
   });
 }
 
+TEST_F(ScalarEvolutionsTest, ProveCondContainingPhiWithSameInputs) {
+  StringRef Assembly = R"(
+    define void @foo(i32 %n, ptr addrspace(1) %p) {
+    ENTRY:
+      %x01 = load atomic i32, ptr addrspace(1) %p unordered, align 8
+      %cmp0 = icmp slt i32 %x01, 0
+      br i1 %cmp0, label %EXIT, label %L0
+
+    L0:
+      %x = phi i32 [ %x01, %ENTRY ], [ %x02, %L2 ]
+      %cmp1 = icmp eq i32 %x, 0
+      br i1 %cmp1, label %EXIT, label %L1
+
+    L1:
+      %iv = phi i32 [ 0, %L0 ], [ %iv.next, %L2 ]
+      %cmp2 = icmp ult i32 %iv, %n
+      br i1 %cmp2, label %L2, label %EXIT
+
+    L2:
+      %iv.next = add nuw nsw i32 %iv, 1
+      %x02 = load atomic i32, ptr addrspace(1) %p unordered, align 8
+      %cmp3 = icmp slt i32 %iv.next, %x
+      br i1 %cmp3, label %L1, label %L0
+
+    EXIT:
+      ret void
+    }
+  )";
+
+  LLVMContext C;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M = parseAssemblyString(Assembly, 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 *LHS = SE.getConstant(APInt(/*numBits=*/32, 0));
+    auto *RHS = SE.getSCEV(getInstructionByName(F, "x"));
+    auto *L1 = getInstructionByName(F, "iv")->getParent();
+    ASSERT_TRUE(L1);
+    // TODO:
+    // - L1 is guarded by 'x01 >=s 0' and 'x != 0';
+    // - %x has same inputs: %x01 and %x02;
+    // Thus L1 is guarded by cond '0 <s x'.
+    // EXPECT_TRUE(SE.isBasicBlockEntryGuardedByCond(L1, ICmpInst::ICMP_SLT,
+    // LHS, RHS));
+  });
+}
+
 }  // end namespace llvm


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