Author: majnemer
Date: Sat Mar 14 17:24:38 2015
New Revision: 232285
URL: http://llvm.org/viewvc/llvm-project?rev=232285&view=rev
Log:
CodeGen: Correctly initialize bitfields with non-constant initializers
It is possible to construct an initializer for a bitfield which is not
constant. Instead of emitting code to initialize the field before the
execution of main, clang would crash.
Modified:
cfe/trunk/lib/CodeGen/CGExprConstant.cpp
cfe/trunk/test/CodeGenCXX/const-init.cpp
Modified: cfe/trunk/lib/CodeGen/CGExprConstant.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprConstant.cpp?rev=232285&r1=232284&r2=232285&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprConstant.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprConstant.cpp Sat Mar 14 17:24:38 2015
@@ -383,14 +383,19 @@ bool ConstStructBuilder::Build(InitListE
if (!EltInit)
return false;
-
+
if (!Field->isBitField()) {
// Handle non-bitfield members.
AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit);
} else {
// Otherwise we have a bitfield.
- AppendBitField(*Field, Layout.getFieldOffset(FieldNo),
- cast<llvm::ConstantInt>(EltInit));
+ if (auto *CI = dyn_cast<llvm::ConstantInt>(EltInit)) {
+ AppendBitField(*Field, Layout.getFieldOffset(FieldNo), CI);
+ } else {
+ // We are trying to initialize a bitfield with a non-trivial constant,
+ // this must require run-time code.
+ return false;
+ }
}
}
Modified: cfe/trunk/test/CodeGenCXX/const-init.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/const-init.cpp?rev=232285&r1=232284&r2=232285&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/const-init.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/const-init.cpp Sat Mar 14 17:24:38 2015
@@ -1,4 +1,4 @@
-// RUN: not %clang_cc1 -verify -triple x86_64-apple-darwin -emit-llvm -o - %s
| FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm -o - %s | FileCheck
%s
// CHECK: @a = global i32 10
int a = 10;
@@ -76,3 +76,10 @@ int &i = reinterpret_cast<int&>(PR9558);
int arr[2];
// CHECK: @pastEnd = constant i32* bitcast (i8* getelementptr (i8, i8* bitcast
([2 x i32]* @arr to i8*), i64 8) to i32*)
int &pastEnd = arr[2];
+
+struct X {
+ long n : 8;
+};
+long k;
+X x = {(long)&k};
+// CHECK: store i8 ptrtoint (i64* @k to i8), i8* getelementptr inbounds
(%struct.X, %struct.X* @x, i32 0, i32 0)
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