From: Dan Gohman <gohman@apple.com>
Date: Tue, 7 Oct 2008 22:03:27 +0000 (+0000)
Subject: Avoid emitting redundant materializations of integer constants
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1e9e8c3bd5ac018296bddb21a2acb8c643303b39;p=oota-llvm.git

Avoid emitting redundant materializations of integer constants
for things like null pointers, which at this level aren't
different from regular integer constants.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57265 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index 17b37a34452..f9cfeb1e972 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -81,7 +81,9 @@ unsigned FastISel::getRegForValue(Value *V) {
   } else if (isa<AllocaInst>(V)) {
     Reg = TargetMaterializeAlloca(cast<AllocaInst>(V));
   } else if (isa<ConstantPointerNull>(V)) {
-    Reg = FastEmit_i(VT, VT, ISD::Constant, 0);
+    // Translate this as an integer zero so that it can be
+    // local-CSE'd with actual integer zeros.
+    Reg = getRegForValue(Constant::getNullValue(TD.getIntPtrType()));
   } else if (ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
     Reg = FastEmit_f(VT, VT, ISD::ConstantFP, CF);
 
@@ -95,8 +97,7 @@ unsigned FastISel::getRegForValue(Value *V) {
                                 APFloat::rmTowardZero) != APFloat::opOK) {
         APInt IntVal(IntBitWidth, 2, x);
 
-        unsigned IntegerReg = FastEmit_i(IntVT.getSimpleVT(), IntVT.getSimpleVT(),
-                                         ISD::Constant, IntVal.getZExtValue());
+        unsigned IntegerReg = getRegForValue(ConstantInt::get(IntVal));
         if (IntegerReg != 0)
           Reg = FastEmit_r(IntVT.getSimpleVT(), VT, ISD::SINT_TO_FP, IntegerReg);
       }