CodeGen: Reduce LValue and CallArgList memory footprint before recommitting r326946

Recent change r326946 (https://reviews.llvm.org/D34367) causes regression in Eigen due to increased
memory footprint of CallArg.

This patch reduces LValue size from 112 to 96 bytes and reduces inline argument count of CallArgList
from 16 to 8.

It has been verified that this will let the added deep AST tree test pass with r326946.

In the long run, CallArg or LValue memory footprint should be further optimized.

Differential Revision: https://reviews.llvm.org/D44445

llvm-svn: 327515

2 files changed, 9 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/CGCall.h b/clang/lib/CodeGen/CGCall.h
index 495baf0f9a2..1cac032aaf9 100644
--- a/clang/lib/CodeGen/CGCall.h
+++ b/clang/lib/CodeGen/CGCall.h
@@ -224,7 +224,7 @@ public:
   /// CallArgList - Type for representing both the value and type of
   /// arguments in a call.
   class CallArgList :
-    public SmallVector<CallArg, 16> {
+    public SmallVector<CallArg, 8> {
   public:
     CallArgList() : StackBase(nullptr) {}
 
diff --git a/clang/lib/CodeGen/CGValue.h b/clang/lib/CodeGen/CGValue.h
index 7d07ea4516c..a32be194968 100644
--- a/clang/lib/CodeGen/CGValue.h
+++ b/clang/lib/CodeGen/CGValue.h
@@ -193,7 +193,7 @@ class LValue {
 
   // The alignment to use when accessing this lvalue.  (For vector elements,
   // this is the alignment of the whole vector.)
-  int64_t Alignment;
+  unsigned Alignment;
 
   // objective-c's ivar
   bool Ivar:1;
@@ -215,13 +215,13 @@ class LValue {
   // to make the default bitfield pattern all-zeroes.
   bool ImpreciseLifetime : 1;
 
-  LValueBaseInfo BaseInfo;
-  TBAAAccessInfo TBAAInfo;
-
   // This flag shows if a nontemporal load/stores should be used when accessing
   // this lvalue.
   bool Nontemporal : 1;
 
+  LValueBaseInfo BaseInfo;
+  TBAAAccessInfo TBAAInfo;
+
   Expr *BaseIvarExp;
 
 private:
@@ -231,7 +231,10 @@ private:
            "initializing l-value with zero alignment!");
     this->Type = Type;
     this->Quals = Quals;
-    this->Alignment = Alignment.getQuantity();
+    const unsigned MaxAlign = 1U << 31;
+    this->Alignment = Alignment.getQuantity() <= MaxAlign
+                          ? Alignment.getQuantity()
+                          : MaxAlign;
     assert(this->Alignment == Alignment.getQuantity() &&
            "Alignment exceeds allowed max!");
     this->BaseInfo = BaseInfo;