[asan] Separate calculation of ShadowBytes from calculating ASanStackFrameLayout
Summary: No functional changes, just refactoring to make D23947 simpler.
Reviewers: eugenis
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23954
llvm-svn: 279982
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 53dd96e..0902f35 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2180,8 +2180,10 @@
// Minimal header size (left redzone) is 4 pointers,
// i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
size_t MinHeaderSize = ASan.LongSize / 2;
- ASanStackFrameLayout L;
- ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize, &L);
+ const ASanStackFrameLayout &L =
+ ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
+ const SmallVector<uint8_t, 64> &ShadowBytes =
+ GetShadowBytesAfterScope(SVD, L);
DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
uint64_t LocalStackSize = L.FrameSize;
bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
@@ -2278,12 +2280,12 @@
// Poison the stack redzones at the entry.
Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
- poisonStackFrame(L.ShadowBytes, IRB, ShadowBase, true);
+ poisonStackFrame(ShadowBytes, IRB, ShadowBase, true);
auto UnpoisonStack = [&](IRBuilder<> &IRB) {
// Do this always as poisonAlloca can be disabled with
// detect_stack_use_after_scope=0.
- poisonStackFrame(L.ShadowBytes, IRB, ShadowBase, false);
+ poisonStackFrame(ShadowBytes, IRB, ShadowBase, false);
if (!StaticAllocaPoisonCallVec.empty()) {
// If we poisoned some allocas in llvm.lifetime analysis,
// unpoison whole stack frame now.
diff --git a/llvm/lib/Transforms/Utils/ASanStackFrameLayout.cpp b/llvm/lib/Transforms/Utils/ASanStackFrameLayout.cpp
index 8e2ff7f..0cd6643 100644
--- a/llvm/lib/Transforms/Utils/ASanStackFrameLayout.cpp
+++ b/llvm/lib/Transforms/Utils/ASanStackFrameLayout.cpp
@@ -47,15 +47,14 @@
return alignTo(Res, Alignment);
}
-void
+ASanStackFrameLayout
ComputeASanStackFrameLayout(SmallVectorImpl<ASanStackVariableDescription> &Vars,
- size_t Granularity, size_t MinHeaderSize,
- ASanStackFrameLayout *Layout) {
+ size_t Granularity, size_t MinHeaderSize) {
assert(Granularity >= 8 && Granularity <= 64 &&
(Granularity & (Granularity - 1)) == 0);
assert(MinHeaderSize >= 16 && (MinHeaderSize & (MinHeaderSize - 1)) == 0 &&
MinHeaderSize >= Granularity);
- size_t NumVars = Vars.size();
+ const size_t NumVars = Vars.size();
assert(NumVars > 0);
for (size_t i = 0; i < NumVars; i++)
Vars[i].Alignment = std::max(Vars[i].Alignment, kMinAlignment);
@@ -64,13 +63,13 @@
SmallString<2048> StackDescriptionStorage;
raw_svector_ostream StackDescription(StackDescriptionStorage);
StackDescription << NumVars;
- Layout->FrameAlignment = std::max(Granularity, Vars[0].Alignment);
- SmallVector<uint8_t, 64> &SB(Layout->ShadowBytes);
- SB.clear();
+
+ ASanStackFrameLayout Layout;
+ Layout.Granularity = Granularity;
+ Layout.FrameAlignment = std::max(Granularity, Vars[0].Alignment);
size_t Offset = std::max(std::max(MinHeaderSize, Granularity),
Vars[0].Alignment);
assert((Offset % Granularity) == 0);
- SB.insert(SB.end(), Offset / Granularity, kAsanStackLeftRedzoneMagic);
for (size_t i = 0; i < NumVars; i++) {
bool IsLast = i == NumVars - 1;
size_t Alignment = std::max(Granularity, Vars[i].Alignment);
@@ -78,7 +77,7 @@
size_t Size = Vars[i].Size;
const char *Name = Vars[i].Name;
assert((Alignment & (Alignment - 1)) == 0);
- assert(Layout->FrameAlignment >= Alignment);
+ assert(Layout.FrameAlignment >= Alignment);
assert((Offset % Alignment) == 0);
assert(Size > 0);
assert(Vars[i].LifetimeSize <= Size);
@@ -87,31 +86,54 @@
size_t NextAlignment = IsLast ? Granularity
: std::max(Granularity, Vars[i + 1].Alignment);
size_t SizeWithRedzone = VarAndRedzoneSize(Vars[i].Size, NextAlignment);
- size_t LifetimeShadowSize =
- (Vars[i].LifetimeSize + Granularity - 1) / Granularity;
- SB.insert(SB.end(), LifetimeShadowSize, kAsanStackUseAfterScopeMagic);
- if (Size / Granularity >= LifetimeShadowSize) {
- SB.insert(SB.end(), Size / Granularity - LifetimeShadowSize, 0);
- if (Size % Granularity)
- SB.insert(SB.end(), Size % Granularity);
- }
- SB.insert(SB.end(), (SizeWithRedzone - Size) / Granularity,
- IsLast ? kAsanStackRightRedzoneMagic
- : kAsanStackMidRedzoneMagic);
Vars[i].Offset = Offset;
Offset += SizeWithRedzone;
- assert(Offset == SB.size() * Granularity);
}
if (Offset % MinHeaderSize) {
- size_t ExtraRedzone = MinHeaderSize - (Offset % MinHeaderSize);
- SB.insert(SB.end(), ExtraRedzone / Granularity,
- kAsanStackRightRedzoneMagic);
- Offset += ExtraRedzone;
+ Offset += MinHeaderSize - (Offset % MinHeaderSize);
}
- Layout->DescriptionString = StackDescription.str();
- Layout->FrameSize = Offset;
- assert((Layout->FrameSize % MinHeaderSize) == 0);
- assert(Layout->FrameSize / Granularity == Layout->ShadowBytes.size());
+ Layout.DescriptionString = StackDescription.str();
+ Layout.FrameSize = Offset;
+ assert((Layout.FrameSize % MinHeaderSize) == 0);
+
+ return Layout;
+}
+
+SmallVector<uint8_t, 64>
+GetShadowBytes(const SmallVectorImpl<ASanStackVariableDescription> &Vars,
+ const ASanStackFrameLayout &Layout) {
+ SmallVector<uint8_t, 64> SB;
+ SB.clear();
+ const size_t NumVars = Vars.size();
+ assert(NumVars > 0);
+ const size_t Granularity = Layout.Granularity;
+ SB.resize(Vars[0].Offset / Granularity, kAsanStackLeftRedzoneMagic);
+ for (const auto &Var : Vars) {
+ SB.resize(Var.Offset / Granularity, kAsanStackMidRedzoneMagic);
+
+ SB.resize(SB.size() + Var.Size / Granularity, 0);
+ if (Var.Size % Granularity)
+ SB.push_back(Var.Size % Granularity);
+ }
+ SB.resize(Layout.FrameSize / Granularity, kAsanStackRightRedzoneMagic);
+ return SB;
+}
+
+SmallVector<uint8_t, 64> GetShadowBytesAfterScope(
+ const SmallVectorImpl<ASanStackVariableDescription> &Vars,
+ const ASanStackFrameLayout &Layout) {
+ SmallVector<uint8_t, 64> SB = GetShadowBytes(Vars, Layout);
+ const size_t Granularity = Layout.Granularity;
+
+ for (const auto &Var : Vars) {
+ const size_t LifetimeShadowSize =
+ (Var.LifetimeSize + Granularity - 1) / Granularity;
+ const size_t Offset = Var.Offset / Granularity;
+ std::fill(SB.begin() + Offset, SB.begin() + Offset + LifetimeShadowSize,
+ kAsanStackUseAfterScopeMagic);
+ }
+
+ return SB;
}
} // llvm namespace