From: Anders Carlsson <andersca@mac.com>
Date: Sat, 20 Dec 2008 20:46:34 +0000 (+0000)
Subject: Change EmitVLASize to take a QualType that must be a variably modified type.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=60d35413662ebdcd1d31e34a8a7c665eb6977f1e;p=clang

Change EmitVLASize to take a QualType that must be a variably modified type.

Emit the size even if the declared type is a variably modified type. This lets us handle

void f(int n) {
  int (*a)[n];

  printf("size: %d\n", sizeof(*a));
}



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@61285 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index 7f4e34d0f9..e8084dcf17 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -160,9 +160,10 @@ void CodeGenFunction::EmitLocalBlockVarDecl(const VarDecl &D) {
         D.getStorageClass() == VarDecl::Register ? ".reg." : ".auto.";
       DeclPtr = GenerateStaticBlockVarDecl(D, true, Class);
     }
+    
+    if (Ty->isVariablyModifiedType())
+      EmitVLASize(Ty);
   } else {
-    const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty);
-
     if (!StackSaveValues.back()) {
       // Save the stack.
       const llvm::Type *LTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
@@ -180,7 +181,7 @@ void CodeGenFunction::EmitLocalBlockVarDecl(const VarDecl &D) {
     const llvm::Type *LElemPtrTy =
       llvm::PointerType::get(LElemTy, D.getType().getAddressSpace());
 
-    llvm::Value *VLASize = EmitVLASize(VAT);
+    llvm::Value *VLASize = EmitVLASize(Ty);
 
     // Allocate memory for the array.
     llvm::Value *VLA = Builder.CreateAlloca(llvm::Type::Int8Ty, VLASize, "vla");
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 4a3bb3f6ca..6f32553118 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -410,29 +410,40 @@ llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT)
   return SizeEntry;
 }
 
-llvm::Value *CodeGenFunction::EmitVLASize(const VariableArrayType *VAT)
+llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty)
 {
-  llvm::Value *&SizeEntry = VLASizeMap[VAT];
-
-  assert(!SizeEntry && "Must not emit the same VLA size more than once!");
-  // Get the element size;
-  llvm::Value *ElemSize;
+  assert(Ty->isVariablyModifiedType() &&
+         "Must pass variably modified type to EmitVLASizes!");
   
-  QualType ElemTy = VAT->getElementType();
-
-  if (const VariableArrayType *ElemVAT = 
-      getContext().getAsVariableArrayType(ElemTy))
-    ElemSize = EmitVLASize(ElemVAT);
+  if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) {
+    llvm::Value *&SizeEntry = VLASizeMap[VAT];
+    
+    assert(!SizeEntry && "Must not emit the same VLA size more than once!");
+    
+    // Get the element size;
+    llvm::Value *ElemSize;
+    
+    QualType ElemTy = VAT->getElementType();
+    
+    if (ElemTy->isVariableArrayType())
+      ElemSize = EmitVLASize(ElemTy);
+    else {
+      // FIXME: We use Int32Ty here because the alloca instruction takes a
+      // 32-bit integer. What should we do about overflow?
+      ElemSize = llvm::ConstantInt::get(llvm::Type::Int32Ty, 
+                                        getContext().getTypeSize(ElemTy) / 8);
+    }
+    
+    llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr());
+    
+    SizeEntry = Builder.CreateMul(ElemSize, NumElements);
+    
+    return SizeEntry;
+  } else if (const PointerType *PT = Ty->getAsPointerType())
+    EmitVLASize(PT->getPointeeType());
   else {
-    // FIXME: We use Int32Ty here because the alloca instruction takes a
-    // 32-bit integer. What should we do about overflow?
-    ElemSize = llvm::ConstantInt::get(llvm::Type::Int32Ty, 
-                                      getContext().getTypeSize(ElemTy) / 8);
+    assert(0 && "unknown VM type!");
   }
-
-  llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr());
-
-  SizeEntry = Builder.CreateMul(ElemSize, NumElements);
-
-  return SizeEntry;
+  
+  return 0;
 }
diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index 9500068814..3b951070ad 100644
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -350,9 +350,10 @@ public:
   // instruction in LLVM instead once it works well enough.  
   llvm::Value *EmitVAArg(llvm::Value *VAListAddr, QualType Ty);
 
-  // EmitVLASize - Generate code for the VLA type. Returns an
-  // lLVM value that corresponds to the size in bytes of the 
-  llvm::Value *EmitVLASize(const VariableArrayType *);
+  // EmitVLASize - Generate code for any VLA size expressions that might occur
+  // in a variably modified type. If Ty is a VLA, will return the value that
+  // corresponds to the size in bytes of the VLA type. Will return 0 otherwise.
+  llvm::Value *EmitVLASize(QualType Ty);
                            
   // GetVLASize - Returns an LLVM value that corresponds to the size in bytes
   // of a variable length array type.