Rearrange handling of jump tables. Highlights:
1. MachineJumpTableInfo is now created lazily for a function the first time
it actually makes a jump table instead of for every function.
2. The encoding of jump table entries is now described by the
MachineJumpTableInfo::JTEntryKind enum. This enum is determined by the
TLI::getJumpTableEncoding() hook, instead of by lots of code scattered
throughout the compiler that "knows" that jump table entries are always
32-bits in pic mode (for example).
3. The size and alignment of jump table entries is now calculated based on
their kind, instead of at machinefunction creation time.
Future work includes using the EntryKind in more places in the compiler,
eliminating other logic that "knows" the layout of jump tables in various
situations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94470 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 5b00adb..966c817 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -21,6 +21,7 @@
#include "llvm/GlobalVariable.h"
#include "llvm/DerivedTypes.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/ErrorHandling.h"
@@ -793,6 +794,22 @@
return TD->getCallFrameTypeAlignment(Ty);
}
+/// getJumpTableEncoding - Return the entry encoding for a jump table in the
+/// current function. The returned value is a member of the
+/// MachineJumpTableInfo::JTEntryKind enum.
+unsigned TargetLowering::getJumpTableEncoding() const {
+ // In non-pic modes, just use the address of a block.
+ if (getTargetMachine().getRelocationModel() != Reloc::PIC_)
+ return MachineJumpTableInfo::EK_BlockAddress;
+
+ // In PIC mode, if the target supports a GPRel32 directive, use it.
+ if (getTargetMachine().getMCAsmInfo()->getGPRel32Directive() != 0)
+ return MachineJumpTableInfo::EK_GPRel32BlockAddress;
+
+ // Otherwise, use a label difference.
+ return MachineJumpTableInfo::EK_LabelDifference32;
+}
+
SDValue TargetLowering::getPICJumpTableRelocBase(SDValue Table,
SelectionDAG &DAG) const {
if (usesGlobalOffsetTable())