Merge constant array and structures. This will create a global variables for arrays and structs that are constant and their initializer is constant. It is on by default but can be disable with the flag -fno-merge-all-constants.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@85991 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index 4f8aef4..b1ceb46 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -19,6 +19,7 @@
#include "clang/AST/DeclObjC.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
+#include "clang/Frontend/CompileOptions.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Intrinsics.h"
#include "llvm/Target/TargetData.h"
@@ -316,6 +317,20 @@
llvm::Value *DeclPtr;
if (Ty->isConstantSizeType()) {
if (!Target.useGlobalsForAutomaticVariables()) {
+
+ // All constant structs and arrays should be global if
+ // their initializer is constant and if the element type is POD.
+ if (CGM.getCompileOpts().MergeAllConstants) {
+ if (Ty.isConstant(getContext())
+ && (Ty->isArrayType() || Ty->isRecordType())
+ && (D.getInit()
+ && D.getInit()->isConstantInitializer(getContext()))
+ && Ty->isPODType()) {
+ EmitStaticBlockVarDecl(D);
+ return;
+ }
+ }
+
// A normal fixed sized variable becomes an alloca in the entry block.
const llvm::Type *LTy = ConvertTypeForMem(Ty);
Align = getContext().getDeclAlignInBytes(&D);
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 521c90d..b4c27a2 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -703,6 +703,9 @@
CmdArgs.push_back("--debug-pass=Structure");
if (Args.hasArg(options::OPT_fdebug_pass_arguments))
CmdArgs.push_back("--debug-pass=Arguments");
+ if (!Args.hasFlag(options::OPT_fmerge_all_constants,
+ options::OPT_fno_merge_all_constants))
+ CmdArgs.push_back("--no-merge-all-constants");
// This is a coarse approximation of what llvm-gcc actually does, both
// -fasynchronous-unwind-tables and -fnon-call-exceptions interact in more