Generate code for LONG indexes to getelementptr instructions more efficiently
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6828 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/InstSelectSimple.cpp b/lib/Target/X86/InstSelectSimple.cpp
index 3da937b..59c9657 100644
--- a/lib/Target/X86/InstSelectSimple.cpp
+++ b/lib/Target/X86/InstSelectSimple.cpp
@@ -1580,9 +1580,26 @@
/// visitCastInst - Here we have various kinds of copying with or without
/// sign extension going on.
void ISel::visitCastInst(CastInst &CI) {
+ Value *Op = CI.getOperand(0);
+ // If this is a cast from a 32-bit integer to a Long type, and the only uses
+ // of the case are GEP instructions, then the cast does not need to be
+ // generated explicitly, it will be folded into the GEP.
+ if (CI.getType() == Type::LongTy &&
+ (Op->getType() == Type::IntTy || Op->getType() == Type::UIntTy)) {
+ bool AllUsesAreGEPs = true;
+ for (Value::use_iterator I = CI.use_begin(), E = CI.use_end(); I != E; ++I)
+ if (!isa<GetElementPtrInst>(*I)) {
+ AllUsesAreGEPs = false;
+ break;
+ }
+
+ // No need to codegen this cast if all users are getelementptr instrs...
+ if (AllUsesAreGEPs) return;
+ }
+
unsigned DestReg = getReg(CI);
MachineBasicBlock::iterator MI = BB->end();
- emitCastOperation(BB, MI, CI.getOperand(0), CI.getType(), DestReg);
+ emitCastOperation(BB, MI, Op, CI.getType(), DestReg);
}
/// emitCastOperation - Common code shared between visitCastInst and
@@ -1937,6 +1954,13 @@
// time.
assert(idx->getType() == Type::LongTy && "Bad GEP array index!");
+ // Most GEP instructions use a [cast (int/uint) to LongTy] as their
+ // operand on X86. Handle this case directly now...
+ if (CastInst *CI = dyn_cast<CastInst>(idx))
+ if (CI->getOperand(0)->getType() == Type::IntTy ||
+ CI->getOperand(0)->getType() == Type::UIntTy)
+ idx = CI->getOperand(0);
+
// We want to add BaseReg to(idxReg * sizeof ElementType). First, we
// must find the size of the pointed-to type (Not coincidentally, the next
// type is the type of the elements in the array).