Basis of dropping uses in llvm.assume.

Summary: This patch adds the basic utilities to deal with dropable uses. dropable uses are uses that we rather drop than prevent transformations, for now they are limited to uses in llvm.assume.

Reviewers: jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: uenoku, lebedev.ri, mgorny, hiraditya, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73404

1 files changed, 33 insertions, 15 deletions

diff --git a/llvm/unittests/IR/KnowledgeRetentionTest.cpp b/llvm/unittests/IR/KnowledgeRetentionTest.cpp
index 46f8c93..36c5e03 100644
--- a/llvm/unittests/IR/KnowledgeRetentionTest.cpp
+++ b/llvm/unittests/IR/KnowledgeRetentionTest.cpp
@@ -25,21 +25,17 @@ static void RunTest(
     StringRef Head, StringRef Tail,
     std::vector<std::pair<StringRef, llvm::function_ref<void(Instruction *)>>>
         &Tests) {
-  std::string IR;
-  IR.append(Head.begin(), Head.end());
-  for (auto &Elem : Tests)
+  for (auto &Elem : Tests) {
+    std::string IR;
+    IR.append(Head.begin(), Head.end());
     IR.append(Elem.first.begin(), Elem.first.end());
-  IR.append(Tail.begin(), Tail.end());
-  LLVMContext C;
-  SMDiagnostic Err;
-  std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
-  if (!Mod)
-    Err.print("AssumeQueryAPI", errs());
-  unsigned Idx = 0;
-  for (Instruction &I : (*Mod->getFunction("test")->begin())) {
-    if (Idx < Tests.size())
-      Tests[Idx].second(&I);
-    Idx++;
+    IR.append(Tail.begin(), Tail.end());
+    LLVMContext C;
+    SMDiagnostic Err;
+    std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
+    if (!Mod)
+      Err.print("AssumeQueryAPI", errs());
+    Elem.second(&*(Mod->getFunction("test")->begin()->begin()));
   }
 }
 
@@ -199,7 +195,29 @@ TEST(AssumeQueryAPI, hasAttributeInAssume) {
                                Attribute::AttrKind::Dereferenceable, 12, true);
       }));
 
-  /// Keep this test last as it modifies the function.
+  Tests.push_back(std::make_pair(
+      "call void @func1(i32* readnone align 32 "
+      "dereferenceable(48) noalias %P, i32* "
+      "align 8 dereferenceable(28) %P1, i32* align 64 "
+      "dereferenceable(4) "
+      "%P2, i32* nonnull align 16 dereferenceable(12) %P3)\n",
+      [](Instruction *I) {
+        CallInst *Assume = BuildAssumeFromInst(I);
+        Assume->insertBefore(I);
+        I->getOperand(1)->dropDroppableUses();
+        I->getOperand(2)->dropDroppableUses();
+        I->getOperand(3)->dropDroppableUses();
+        AssertMatchesExactlyAttributes(
+            Assume, I->getOperand(0),
+            "(readnone|align|dereferenceable|noalias)");
+        AssertMatchesExactlyAttributes(Assume, I->getOperand(1), "");
+        AssertMatchesExactlyAttributes(Assume, I->getOperand(2), "");
+        AssertMatchesExactlyAttributes(Assume, I->getOperand(3), "");
+        AssertHasTheRightValue(Assume, I->getOperand(0),
+                               Attribute::AttrKind::Alignment, 32, true);
+        AssertHasTheRightValue(Assume, I->getOperand(0),
+                               Attribute::AttrKind::Dereferenceable, 48, true);
+      }));
   Tests.push_back(std::make_pair(
       "call void @func(i32* nonnull align 4 dereferenceable(16) %P, i32* align "
       "8 noalias %P1)\n",