Support for constant islands in the ARM JIT.

Since the ARM constant pool handling supercedes the standard LLVM constant
pool entirely, the JIT emitter does not allocate space for the constants,
nor initialize the memory. The constant pool is considered part of the 
instruction stream.

Likewise, when resolving relocations into the constant pool, a hook into
the target back end is used to resolve from the constant ID# to the
address where the constant is stored.

For now, the support in the ARM emitter is limited to 32-bit integer. Future
patches will expand this to the full range of constants necessary.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58338 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/ExecutionEngine/JIT/JITEmitter.cpp b/lib/ExecutionEngine/JIT/JITEmitter.cpp
index 688d498..44e6638 100644
--- a/lib/ExecutionEngine/JIT/JITEmitter.cpp
+++ b/lib/ExecutionEngine/JIT/JITEmitter.cpp
@@ -1011,6 +1011,11 @@ void* JITEmitter::allocateSpace(intptr_t Size, unsigned Alignment) {
 }
 
 void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
+  if (TheJIT->getJITInfo().hasCustomConstantPool()) {
+    DOUT << "JIT: Target has custom constant pool handling. Omitting standard "
+            "constant pool\n";
+    return;
+  }
   const std::vector<MachineConstantPoolEntry> &Constants = MCP->getConstants();
   if (Constants.empty()) return;
 
@@ -1124,6 +1129,10 @@ void *JITEmitter::finishFunctionStub(const GlobalValue* F) {
 // method.
 //
 intptr_t JITEmitter::getConstantPoolEntryAddress(unsigned ConstantNum) const {
+  if (TheJIT->getJITInfo().hasCustomConstantPool()) {
+    return TheJIT->getJITInfo().getCustomConstantPoolEntryAddress(ConstantNum);
+  }
+
   assert(ConstantNum < ConstantPool->getConstants().size() &&
          "Invalid ConstantPoolIndex!");
   return (intptr_t)ConstantPoolBase +