From d335c1317b6170918311fcbccc39fe31b3a84bda Mon Sep 17 00:00:00 2001
From: Arthur Eubanks <aeubanks@google.com>
Date: Mon, 22 Jun 2020 13:22:16 -0700
Subject: [PATCH] Fix dynamic alloca detection in CloneBasicBlock

Summary:
Simply check AI->isStaticAlloca instead of reimplementing checks for
static/dynamic allocas.

Reviewers: efriedma

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D82328
---
 llvm/lib/Transforms/Utils/CloneFunction.cpp     |  9 ++--
 llvm/unittests/Transforms/Utils/CloningTest.cpp | 59 +++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index fce926f..788983c 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -46,7 +46,7 @@ BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
   if (BB->hasName())
     NewBB->setName(BB->getName() + NameSuffix);
 
-  bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
+  bool hasCalls = false, hasDynamicAllocas = false;
   Module *TheModule = F ? F->getParent() : nullptr;
 
   // Loop over all instructions, and copy them over.
@@ -62,18 +62,15 @@ BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
 
     hasCalls |= (isa<CallInst>(I) && !isa<DbgInfoIntrinsic>(I));
     if (const AllocaInst *AI = dyn_cast<AllocaInst>(&I)) {
-      if (isa<ConstantInt>(AI->getArraySize()))
-        hasStaticAllocas = true;
-      else
+      if (!AI->isStaticAlloca()) {
         hasDynamicAllocas = true;
+      }
     }
   }
 
   if (CodeInfo) {
     CodeInfo->ContainsCalls          |= hasCalls;
     CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
-    CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
-                                        BB != &BB->getParent()->getEntryBlock();
   }
   return NewBB;
 }
diff --git a/llvm/unittests/Transforms/Utils/CloningTest.cpp b/llvm/unittests/Transforms/Utils/CloningTest.cpp
index 28ad4bc..fc0b3de 100644
--- a/llvm/unittests/Transforms/Utils/CloningTest.cpp
+++ b/llvm/unittests/Transforms/Utils/CloningTest.cpp
@@ -659,6 +659,65 @@ static int GetDICompileUnitCount(const Module& M) {
   return 0;
 }
 
+TEST(CloneFunction, CloneEmptyFunction) {
+  StringRef ImplAssembly = R"(
+    define void @foo() {
+      ret void
+    }
+    declare void @bar()
+  )";
+
+  LLVMContext Context;
+  SMDiagnostic Error;
+
+  auto ImplModule = parseAssemblyString(ImplAssembly, Error, Context);
+  EXPECT_TRUE(ImplModule != nullptr);
+  auto *ImplFunction = ImplModule->getFunction("foo");
+  EXPECT_TRUE(ImplFunction != nullptr);
+  auto *DeclFunction = ImplModule->getFunction("bar");
+  EXPECT_TRUE(DeclFunction != nullptr);
+
+  ValueToValueMapTy VMap;
+  SmallVector<ReturnInst *, 8> Returns;
+  ClonedCodeInfo CCI;
+  CloneFunctionInto(DeclFunction, ImplFunction, VMap, true, Returns, "", &CCI);
+
+  EXPECT_FALSE(verifyModule(*ImplModule, &errs()));
+  EXPECT_FALSE(CCI.ContainsCalls);
+  EXPECT_FALSE(CCI.ContainsDynamicAllocas);
+}
+
+TEST(CloneFunction, CloneFunctionWithInalloca) {
+  StringRef ImplAssembly = R"(
+    declare void @a(i32* inalloca)
+    define void @foo() {
+      %a = alloca inalloca i32
+      call void @a(i32* inalloca %a)
+      ret void
+    }
+    declare void @bar()
+  )";
+
+  LLVMContext Context;
+  SMDiagnostic Error;
+
+  auto ImplModule = parseAssemblyString(ImplAssembly, Error, Context);
+  EXPECT_TRUE(ImplModule != nullptr);
+  auto *ImplFunction = ImplModule->getFunction("foo");
+  EXPECT_TRUE(ImplFunction != nullptr);
+  auto *DeclFunction = ImplModule->getFunction("bar");
+  EXPECT_TRUE(DeclFunction != nullptr);
+
+  ValueToValueMapTy VMap;
+  SmallVector<ReturnInst *, 8> Returns;
+  ClonedCodeInfo CCI;
+  CloneFunctionInto(DeclFunction, ImplFunction, VMap, true, Returns, "", &CCI);
+
+  EXPECT_FALSE(verifyModule(*ImplModule, &errs()));
+  EXPECT_TRUE(CCI.ContainsCalls);
+  EXPECT_TRUE(CCI.ContainsDynamicAllocas);
+}
+
 TEST(CloneFunction, CloneFunctionToDifferentModule) {
   StringRef ImplAssembly = R"(
     define void @foo() {
-- 
2.7.4