Bug 18567: Fix constantexpr pointer casts with address spaces.

[arsenm]

Summary

Getting a pointer into a struct at a non-zero offset would try to use the default address space.

[pekka.jaaskelainen]

Seems OK (to my Clang novice eyes). Can this be backported to LLVM 3.4.1 also?

[• jeroenk]

A number of related bugs were fixed in r197036; see also D2241 (I doubt the test cases from there were ever committed). I've added two more related test cases to PR18567.

[arsenm]

Committed r206478. The other testcases aren't related, and I have a separate patch somewhere that addresses those.

lib/CodeGen/CGExprConstant.cpp

 
       // Apply offset if necessary.
       if (!Offset->isNullValue()) {
-        llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Int8PtrTy);
+        unsigned AS = C->getType()->getPointerAddressSpace();
+        llvm::Type *CharPtrTy = Int8Ty->getPointerTo(AS);
+        llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, CharPtrTy);
         Casted = llvm::ConstantExpr::getGetElementPtr(Casted, Offset);
         C = llvm::ConstantExpr::getPointerCast(Casted, C->getType());
       }

test/CodeGenOpenCL/address-space-constant-initializers.cl

+// RUN: %clang_cc1 %s -ffake-address-space-map -emit-llvm -o - | FileCheck %s
+
+typedef struct {
+    int i;
+    float f; // At non-zero offset.
+} ArrayStruct;
+
+__constant ArrayStruct constant_array_struct = { 0, 0.0f };
+
+typedef struct {
+    __constant float* constant_float_ptr;
+} ConstantArrayPointerStruct;
+
+// CHECK: %struct.ConstantArrayPointerStruct = type { float addrspace(3)* }
+// CHECK: addrspace(3) global %struct.ConstantArrayPointerStruct { float addrspace(3)* bitcast (i8 addrspace(3)* getelementptr (i8 addrspace(3)* bitcast (%struct.ArrayStruct addrspace(3)* @constant_array_struct to i8 addrspace(3)*), i64 4) to float addrspace(3)*) }
+// Bug  18567
+__constant ConstantArrayPointerStruct constant_array_pointer_struct = {
+    &constant_array_struct.f
+};
+