ExactAssemblyScope: Force the pools not to be emitted

There was a bug where the AArch32 MacroAssembler would still generate
pools inside ExactAssemblyScope. In order to avoid this, this patch
renames the `kCheckPools` policy to `kBlockPools`. Saying "check"
implies we only assert that pools are not generated, which is not the case.

Change-Id: Ica717f56f99c7363add5361076174e8e827dd81c

3 files changed, 20 insertions, 7 deletions

diff --git a/src/aarch32/macro-assembler-aarch32.cc b/src/aarch32/macro-assembler-aarch32.cc
index 1e7a6b52..86d26064 100644
--- a/src/aarch32/macro-assembler-aarch32.cc
+++ b/src/aarch32/macro-assembler-aarch32.cc
@@ -302,6 +302,7 @@ void VeneerPoolManager::RemoveLabel(Label* label) {
 
 
 void VeneerPoolManager::EmitLabel(Label* label, Label::Offset emitted_target) {
+  VIXL_ASSERT(!IsBlocked());
   // Define the veneer.
   Label veneer;
   masm_->Bind(&veneer);
@@ -419,7 +420,7 @@ void MacroAssembler::PerformEnsureEmit(Label::Offset target, uint32_t size) {
       generate_veneers = true;
     }
   }
-  if (generate_veneers) {
+  if (!veneer_pool_manager_.IsBlocked() && generate_veneers) {
     {
       ExactAssemblyScopeWithoutPoolsCheck
           guard(this,
@@ -433,7 +434,8 @@ void MacroAssembler::PerformEnsureEmit(Label::Offset target, uint32_t size) {
   // Check if the macro-assembler's internal literal pool should be emitted
   // to avoid any overflow. If we already generated the veneers, we can
   // emit the pool (the branch is already done).
-  if ((target > literal_target) || (option == kNoBranchRequired)) {
+  if (!literal_pool_manager_.IsBlocked() &&
+      ((target > literal_target) || (option == kNoBranchRequired))) {
     EmitLiteralPool(option);
   }
   BindHelper(&after_pools);
@@ -458,6 +460,7 @@ void MacroAssembler::ComputeCheckpoint() {
 
 void MacroAssembler::EmitLiteralPool(LiteralPool* const literal_pool,
                                      EmitOption option) {
+  VIXL_ASSERT(!literal_pool_manager_.IsBlocked());
   if (literal_pool->GetSize() > 0) {
 #ifdef VIXL_DEBUG
     for (LiteralPool::RawLiteralListIterator literal_it =
diff --git a/src/aarch32/macro-assembler-aarch32.h b/src/aarch32/macro-assembler-aarch32.h
index 706b5a5e..9bb725f3 100644
--- a/src/aarch32/macro-assembler-aarch32.h
+++ b/src/aarch32/macro-assembler-aarch32.h
@@ -435,7 +435,8 @@ class MacroAssembler : public Assembler, public MacroAssemblerInterface {
       ITScope it_scope(this, &c);
       instr_callback.emit(this, c, literal);
     }
-    if (!literal->IsManuallyPlaced() && !literal->IsBound()) {
+    if (!literal->IsManuallyPlaced() && !literal->IsBound() &&
+        !literal_pool_manager_.IsBlocked()) {
       if (WasInsertedTooFar(literal)) {
         // The instruction's data is too far: revert the emission
         GetBuffer()->Rewind(cursor);
diff --git a/src/code-generation-scopes-vixl.h b/src/code-generation-scopes-vixl.h
index 7e47d5ed..40c288c5 100644
--- a/src/code-generation-scopes-vixl.h
+++ b/src/code-generation-scopes-vixl.h
@@ -163,12 +163,21 @@ class EmissionCheckScope : public CodeBufferCheckScope {
 
   virtual ~EmissionCheckScope() { Close(); }
 
-  enum PoolPolicy { kIgnorePools, kCheckPools };
+  enum PoolPolicy {
+    // Do not forbid pool emission inside the scope. Pools will not be emitted
+    // on `Open` either.
+    kIgnorePools,
+    // Force pools to be generated on `Open` if necessary and block their
+    // emission inside the scope.
+    kBlockPools,
+    // Deprecated, but kept for backward compatibility.
+    kCheckPools = kBlockPools
+  };
 
   void Open(MacroAssemblerInterface* masm,
             size_t size,
             SizePolicy size_policy = kMaximumSize) {
-    Open(masm, size, size_policy, kCheckPools);
+    Open(masm, size, size_policy, kBlockPools);
   }
 
   void Close() {
@@ -183,7 +192,7 @@ class EmissionCheckScope : public CodeBufferCheckScope {
     //   - Check the code generation limit was not exceeded.
     //   - Release the pools.
     CodeBufferCheckScope::Close();
-    if (pool_policy_ == kCheckPools) {
+    if (pool_policy_ == kBlockPools) {
       masm_->ReleasePools();
     }
     VIXL_ASSERT(!initialised_);
@@ -202,7 +211,7 @@ class EmissionCheckScope : public CodeBufferCheckScope {
     }
     masm_ = masm;
     pool_policy_ = pool_policy;
-    if (pool_policy_ == kCheckPools) {
+    if (pool_policy_ == kBlockPools) {
       // To avoid duplicating the work to check that enough space is available
       // in the buffer, do not use the more generic `EnsureEmitFor()`. It is
       // done below when opening `CodeBufferCheckScope`.