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

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Merged
merged 1 commit into from
Oct 11, 2024
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[SandboxIR] Add utility function to find the base Value for Mem instructions #112030

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1 change: 1 addition & 0 deletions llvm/include/llvm/SandboxIR/Context.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
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10 changes: 10 additions & 0 deletions llvm/include/llvm/SandboxIR/Utils.h
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Expand Up @@ -49,6 +49,16 @@ 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) {
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Why not use LLVM's name getUnderlyingObject() ? getMemInstructionBase() is a better name, but since we are just wrapping LLVM's getUnderlyingObject() we should probably stick to the same name.

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Because this does more than just wrap getUnderlyingObject. It also finds the pointer operand.

static_assert(std::is_same_v<LoadOrStoreT, LoadInst> ||
std::is_same_v<LoadOrStoreT, StoreInst>,
"Expected sandboxir::Load or sandboxir::Store!");
return LSI->Ctx.getOrCreateValue(
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Do we need getOrCreateValue() ? I assume that sandbox IR would have been generated for the whole function. That would remove the need for friend class Utils in Context.

auto *V = LSI->Ctx.getValue( getUnderlyingObject(LSI->getPointerOperand()->Val));
assert(V != nullptr && "Missing Sandbox IR value!");
return V;

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getUnderlyingObject returns an llvm::Value, getOrCreateValue converts that to a sandboxir::Value.

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Yes, but there is also a public sandboxir::Context::getValue(llvm::Value *) that converts LLVM IR to Sandbox IR

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) {
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32 changes: 32 additions & 0 deletions llvm/unittests/SandboxIR/UtilsTest.cpp
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Expand Up @@ -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));
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These checks are OK, but we are not actually checking what the returned value actually is.

Some checks like this would also help:

EXPECT_EQ(sandboxir::Utils::getMemInsructionBase(St0), Ctx.getValue(LLVMSt0));

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will add

}
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