[SandboxIR] Add utility function to find the base Value for Mem instructions (llvm#112030)

Author: Sterling-Augustine

llvm/include/llvm/SandboxIR/Context.h

@@ -68,6 +68,7 @@ class Context {
   }
   /// Get or create a sandboxir::Constant from an existing LLVM IR \p LLVMC.
   Constant *getOrCreateConstant(llvm::Constant *LLVMC);
+  friend class Utils; // For getMemoryBase
 
   // Friends for getOrCreateConstant().
 #define DEF_CONST(ID, CLASS) friend class CLASS;

llvm/include/llvm/SandboxIR/Utils.h

@@ -50,6 +50,16 @@ class Utils {
     return const_cast<Instruction *>(I);
   }
 
+  /// \Returns the base Value for load or store instruction \p LSI.
+  template <typename LoadOrStoreT>
+  static Value *getMemInstructionBase(const LoadOrStoreT *LSI) {
+    static_assert(std::is_same_v<LoadOrStoreT, LoadInst> ||
+                      std::is_same_v<LoadOrStoreT, StoreInst>,
+                  "Expected sandboxir::Load or sandboxir::Store!");
+    return LSI->Ctx.getOrCreateValue(
+        getUnderlyingObject(LSI->getPointerOperand()->Val));
+  }
+
   /// \Returns the number of bits required to represent the operands or return
   /// value of \p V in \p DL.
   static unsigned getNumBits(Value *V, const DataLayout &DL) {

llvm/unittests/SandboxIR/UtilsTest.cpp

@@ -215,3 +215,35 @@ define void @foo(float %arg0, double %arg1, i8 %arg2, i64 %arg3, ptr %arg4) {
   EXPECT_EQ(sandboxir::Utils::getNumBits(L2), 8u);
   EXPECT_EQ(sandboxir::Utils::getNumBits(L3), 64u);
 }
+
+TEST_F(UtilsTest, GetMemBase) {
+  parseIR(C, R"IR(
+define void @foo(ptr %ptrA, float %val, ptr %ptrB) {
+bb:
+  %gepA0 = getelementptr float, ptr %ptrA, i32 0
+  %gepA1 = getelementptr float, ptr %ptrA, i32 1
+  %gepB0 = getelementptr float, ptr %ptrB, i32 0
+  %gepB1 = getelementptr float, ptr %ptrB, i32 1
+  store float %val, ptr %gepA0
+  store float %val, ptr %gepA1
+  store float %val, ptr %gepB0
+  store float %val, ptr %gepB1
+  ret void
+}
+)IR");
+  llvm::Function &Foo = *M->getFunction("foo");
+  sandboxir::Context Ctx(C);
+  sandboxir::Function *F = Ctx.createFunction(&Foo);
+
+  auto It = std::next(F->begin()->begin(), 4);
+  auto *St0 = cast<sandboxir::StoreInst>(&*It++);
+  auto *St1 = cast<sandboxir::StoreInst>(&*It++);
+  auto *St2 = cast<sandboxir::StoreInst>(&*It++);
+  auto *St3 = cast<sandboxir::StoreInst>(&*It++);
+  EXPECT_EQ(sandboxir::Utils::getMemInstructionBase(St0),
+            sandboxir::Utils::getMemInstructionBase(St1));
+  EXPECT_EQ(sandboxir::Utils::getMemInstructionBase(St2),
+            sandboxir::Utils::getMemInstructionBase(St3));
+  EXPECT_NE(sandboxir::Utils::getMemInstructionBase(St0),
+            sandboxir::Utils::getMemInstructionBase(St3));
+}